Biological risks associated with consumption of reptile products
Simone Magnino a,!, Pierre Colin b, Eduardo Dei-Cas c, Mogens Madsen d, Jim McLauchlin e, Karsten Nöckler f,Miguel Prieto Maradona g, Eirini Tsigarida h,1, Emmanuel Vanopdenbosch i, Carlos Van Peteghem j
a Istituto Zoopro!lattico Sperimentale della Lombardia e dell'Emilia Romagna “Bruno Ubertini”, Sezione Diagnostica di Pavia, Strada Campeggi 61, 27100 Pavia, Italyb Université de Bretagne Occidentale, Ecole Supérieure de Microbiologie et de Sécurité Alimentaire, Technopôle Brest-Iroise, 29280 Plouzané, Francec Parasitology-Mycology Service, Microbiology Department, EA3609 Faculty of Medicine, Lille 2 University, University Hospital Centre & IFR-142 Lille Pasteur Institute, Franced Technical University of Denmark, DIANOVA, Incuba Science Park Skejby, 102 Brendstrupgaardsvej, DK-8200 Aarhus N, Denmarke Health Protection Agency Food, Water & Environmental Microbiology Network, London WC1V 7PP, United Kingdomf Bundesinstitut für Risikobewertung, Federal Institute for Risk Assessment, Diedersdorfer Weg 1, 12277 Berlin, Germanyg Department of Food Hygiene and Technology, Veterinary Faculty, University of León, 24071 León, Spainh Scienti!c Panel on Biological Hazards, European Food Safety Authority, Largo N. Palli 5/A, 43100 Parma, Italyi Veterinary and Agrochemical Research Centre, Groeselenberg 99, B-1180 Brussels, Belgiumj Faculty of Pharmaceutical Sciences, Laboratory of Food Analysis, University of Ghent, Harelbekestraat 72, B-9000 Ghent, Belgium
a b s t r a c ta r t i c l e i n f o
Article history:Received 27 March 2009Received in revised form 25 June 2009Accepted 4 July 2009
The consumption of a wide variety of species of reptiles caught from the wild has been an important sourceof protein for humans world-wide for millennia. Terrapins, snakes, lizards, crocodiles and iguanas are nowfarmed and the consumption and trade of their meat and other edible products have recently increased insome areas of the world. Biological risks associated with the consumption of products from both farmed andwild reptile meat and eggs include infections caused by bacteria (Salmonella spp., Vibrio spp.), parasites(Spirometra, Trichinella, Gnathostoma, pentastomids), as well as intoxications by biotoxins. For crocodiles,Salmonella spp. constitute a signi!cant public health risk due to the high intestinal carrier rate which isre"ected in an equally high contamination rate in their fresh and frozen meat. There is a lack of informationabout the presence of Salmonella spp. in meat from other edible reptilians, though captive reptiles used aspets (lizards or turtles) are frequently carriers of these bacteria in Europe.Parasitic protozoa in reptiles represent a negligible risk for public health compared to parasitic metazoans, ofwhich trichinellosis, pentastomiasis, gnathostomiasis and sparganosis can be acquired through consumptionof contaminated crocodile, monitor lizard, turtle and snake meat, respectively. Other reptiles, although foundto harbour the above parasites, have not been implicated with their transmission to humans. Freezingtreatment inactivates Spirometra and Trichinella in crocodile meat, while the effectiveness of freezing of otherreptilian meat is unknown. Biotoxins that accumulate in the "esh of sea turtles may cause chelonitoxism, atype of food poisoning with a high mortality rate in humans. Infections by fungi, including yeasts, and viruseswidely occur in reptiles but have not been linked to a human health risk through the contamination of theirmeat. Currently there are no indications that natural transmissible spongiform encephalopathies (TSEs)occur in reptilians. The feeding of farmed reptiles with non-processed and recycled animal products is likelyto increase the occurrence of biological hazards in reptile meat. Application of GHP, GMP and HACCPprocedures, respectively at farm and slaughterhouse level, is crucial for controlling the hazards.
The class Reptilia includes numerous extinct taxons and fourextant orders: Crocodilia (crocodiles, caimans, alligators, gharials),Testudines (turtles, tortoises, terrapins), Squamata (lizards, geckos,iguanas, snakes) and Sphenodontia (tuatara), the latter being anendangered species which is not to be considered further. Withregard to the consumption of a wide variety of species of reptilescaught from the wild, turtles (meat and eggs) are probably the mostheavily exploited worldwide. In 1835 when in the GalapagosArchipelago on the HMS Beagle, Charles Darwin reported meetinga party of Spanish sailors who were salting giant tortoise meat to eaton board ship, and when exploring inland “lived entirely upontortoise meat: the breast plate roasted… with "esh on it is verygood; and young tortoises make excellent soup” (Darwin, 1854).Terrapins, crocodiles, snakes, iguanas and lizards are still todaylocally important food sources (Klemens and Thorbjarnarson, 1995).The increasing demand of some reptile meat (e.g. from terrapins,crocodiles, caimans, alligators and iguanas) in some regions hasresulted in the development of breeding programs in more than 30countries in North, Central and South America, Africa, Asia andAustralia. Therefore, the consideration of food-borne disease fromreptiles is becoming more important (Hutton and Webb, 2003).Reptiles can be carriers of a variety of disease causing agents andtheir meat can become contaminated depending on the housing,feeding, and hygienic practices under which they are reared orslaughtered. For reptiles reared in aquatic environments, the qualityof water in which animals are raised is also important. However,hygienic measures at farm level, slaughtering and processingprocedures can signi!cantly reduce the risk of a foodborne infectionfor consumer after consumption of meat originating from farmedreptiles.
This review is based on the preparatory work of an ad hocWorkingGroup set up for drafting an opinion subsequently issued by theScienti!c Panel on Biological Hazards (BIOHAZ Panel) of the EuropeanFood Safety Authority (EFSA) on public health risks involved in thehuman consumption of farmed or ranched reptilemeat (EFSA, 2007a).The scope of this review is a wider assessment of biological risks thatare associated with the consumption of reptile products, althoughedible products derived from wild reptiles, either legally or illegallycaught and traded (the latter case, also known as “bush meat”) havenot been considered in detail, unless relevant for risks that mightoccur with farmed reptiles. The term of “reptile meat” is limited tomuscle tissue, blood con!ned to muscle vasculature, bone and bonemarrow, and any other tissues (for example fat) that may beconsidered inseparable from muscle, as well as internal organs such
as liver. Risks associated with other reptile products, such as skins,carapace, blood, eggs and medicinal products will only be brie"yconsidered. Risks due to viruses, prions, bacteria, fungi, parasites, andbiotoxins are considered, that are either present in the product at thetime of slaughter or become a contaminant, regardless of the meansby which they may be affected by storage, processing or retail of theproduct. The assessment of public health concerns is based on a ‘farmto fork’ approach and considers risks derived from farming practicesincluding the settings, housing, diet, veterinary interventions, meth-ods of slaughter, processing and retailing practices. Informationconcerning the farming of reptiles for meat production, the biologicalhazards associated with reptile meat, and data on consumption pat-terns is often fragmentary and not readily available. As a consequence,a risk pro!le approach will be presented in this paper.
2. Examples of farming systems for reptiles reared for meat
Reptiles are farmed for human consumption in various parts of theworld, including crocodiles in Zimbabwe, Papua New Guinea,Australia and England, alligators in North America, snakes in Asiaand North America, iguanas in Central and South America, and turtlesand terrapins in China, Japan and South-East Asia. Reptiles have manydifferent feeding habits, and although some, such as the land tortoises,are completely vegetarian, most of them have a varied diet feeding onsome form of animal life depending on the habitats they occur. Thediet of reptiles therefore includes arthropods, insects, molluscs,amphibians, birds, mammals, !sh, or other reptiles. For example,alligators are almost totally carnivorous, and in thewild, small animalswill eat snails, frogs, insects, and small !sh. As they become larger,alligators will eat !sh, turtles, snakes, waterfowl, small mammals andeven smaller alligators.
2.1. Crocodilia
The Nile crocodile (Crocodylus niloticus) is native to Africa, mayreach up to 7 m in length and is reared in many countries includingKenya, Zimbabwe, Tanzania, South Africa, Israel, Indonesia, France,Japan and Spain, with a licence for its farming formeat awarded for the!rst time in the UK in 2006. Other crocodilians are also commerciallyreared, inparticular the saltwater crocodile (Crocodylus porosus)whichmay reach 9m in length and is farmed in Australia, Papua NewGuinea,Thailand and other countries, the freshwater crocodile (Crocodylusjohnstoni), also farmed inAustralia, and a hybrid between the saltwatercrocodile and the Siamese crocodile (Crocodylus siamensis), which isfarmed extensively in Thailand and Cambodia. The American alligator(Alligatormississippiensis) is typically about 4.5m long and is farmed in
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Southern US (Georgia, Florida, Texas, Louisiana) mostly for theproduction of hides for leather products, but with an establishedmarket also for meat. The equivalent for crocodiles and alligators inCentral and South America are caimans. Among them, the species withthe widest distribution is Caiman crocodilus, which is extremelyadaptable to all lowland wetland and riverine habitats, and thus hasbecome established from Mexico to Peru and Brazil. In comparison toother crocodilians, caimans are smaller, with males and femalesgenerally reaching 2.5 m and 1.5 m, respectively. Caimans supply thevast majority of the hide market in South America, and are alsoexploited for their meat. Sustainable programs for these reptiles havebeen developed in LatinAmerica, namely inVenezuela for C. crocodilus,and in Brazil and Argentina for the related species C. yacare (Larrieraand Imhof, 2006; Thorbjarnarson and Velasco, 1999).
Rearing of crocodiles is performed in two ways, namely byranching or farming. Ranching depends on the presence of asustainable wild population, as eggs or hatchlings which are collectedfrom natural habitats and reared to harvest size in captivity.Collections are carefully regulated by quotas and collectors' permitsby wildlife authorities, and replenishment of the wild populationensures restocking of a certain percentage of the animals reared incaptivity. Thus, permit holders in Zimbabwe must return 5% of thecrocodiles reared in captivity to natural habitats (Child, 1984). Farm-ing is based on captive breeding and although it provides betteropportunities for controlled management, is more demanding on theprovision of proper physical facilities for breeding animals, andmanagement of adults of considerable body sizes. Farming is lessfavoured by wildlife conservationists, as it may exist as a closedproduction system independent of (and with no particular interest in)sustainable natural crocodile populations. In practice, the crocodileindustry is based on a mixture of ranching and farming. The mainsource of rearing stock is derived from collection of eggs or hatchlingsfrom natural habitats, but many operators also supplement their stockwith offspring from captive breeding animals. Common for the twosystems is the incubation of fertilized eggs under controlledtemperature and humidity conditions, the rearing of young hatchlingsin separate heated ponds, and the grow-out of rearing stock in earthenor concrete ponds to harvest size which is usually 2–3 years. Thesurvival rate under captive rearing may approach 75% of viable eggs,while estimated survival rates in the wild are ~5% due to predation ofeggs and hatchlings (Hutton and van Jaarsveldt, 1987).
Crocodiles are carnivores, and their diet must be based on animalprotein which may come from both aquatic and terrestrial animals.Attempts to substitute animal protein partly or in full with vegetablesources have generally been unsuccessful, resulting in poor growth,runting and mortalities particularly in young hatchlings. However,recent attempts of feeding pelleted diets to crocodiles have beensuccessful (Peucker and Jack, 2006). The natural diet of newly hatchedcrocodiles is insects, larvae etc. which animals must be taught to eat,e.g. by farm attendants feeding insects, or hand-feeding with smallpieces of e.g. minced meat. After some months, crocodiles are fedsmall !sh which form the main part of the natural diet, that is onlyoccasionally supplemented with larger birds and mammals. The dietof captive crocodiles at slaughter age usually re"ects the availableanimal protein sources that are locally available. In Zimbabwe, themain diet is composed of kapenta !sh supplemented with game meat(particularly elephant) from hunting and culling (Hutton and vanJaarsveldt, 1987), while the diet consists almost exclusively of !sh inThailand and Australia (Suvanakorn and Youngprapakorn, 1987). InIsrael (Ben-Moshe, 1987) and also in England, culled poultry mayconstitute 50% or more of the diet, and this practice carries a furtherrisk of introducing pathogens such as Salmonella (especially S.Enteritidis) to the reptilian micro"ora.
For public health purposes, it is important to note that crocodilesare primarily reared for their highly valued skins (leather), while meatis usually a by-product. The main concern in carcass preparation is
indeed to ensure and preserve the quality of the skin. Contaminationof the meat is likely because the skin is valuable and must be removedcarefully. Because the skin does not ‘peel’ off easily, crocodiles must beskinned on a "at surface, which provides greater opportunity forcontamination of the meat (Madsen et al., 1992). Meat harvested forhuman consumption almost exclusively comprises the tail and thedorsal !llets, while the rest of the carcass may be fed back to thecrocodiles.
2.2. Squamata
Different species of iguanas and snakes are farmed and traded fortheir meat, mostly in America and Asia. Farming of large lizards alsooccurs, e.g. in Argentina where the omnivorous tegus (Tupinambisspp.) have recently begun to be reared for their skins and meat,whereas other large carnivorous lizards, such as the monitor lizards,are not farmed because they are considered dif!cult to feed and toraise economically (NRC, 1991).
2.2.1. SnakesFarming of snakes is intended for different purposes such as venom
collection (for antivenom production), skin andmeat production. Thereare few reports available on commercial snake farms, e.g. in the centralTerai district of Bara in central Nepal, where snakes are kept for theproduction of venom,meat and skin in order tomeet the demand in theinternational market. These goods are exported to many European andAsian countries and to Australia. New animals are provided to the farmfrom “snake collection centres” that operate in national parks andwildlife reserves and are responsible for breeding. The snakes aresupplied with water and fed with chicken and frogs at weekly or evenmonthly intervals. Snakes (including rattlesnake and python) are alsofarmed in theUS for theproductionofmeat forhuman consumption andare available in the EU market. Reticulated python (Python reticulatus)farms have become established over the last 20 years in many Asiancountries, in particular in Southeast Asia. Although the main interest offarming this species is for skinproduction, themeat is alsoharvested andhighly prized as a delicacy. Burmese pythons (Pythonmolurus bivittatus)are farmed in Southeast Asia (Vietnam). Meat from this latter species iscurrently imported into EU.
2.2.2. IguanasTraditionally, iguanas have been used as a source of food for more
than 7000 years in part of Central and South America. However, due toexcessive hunting of both animals and eggs and destruction of theirtropical forest habitat, wild populations have become extinct in somecountries and have hugely decreased in others. Breeding programsoriginally intended to raise animals for their release back into thewildhave progressively developed in several countries, including Panama,Costa Rica, Guatemala, Nicaragua, Belize, Honduras, El Salvador,Colombia, and Venezuela (Eilers et al., 2002). Further to theconservation purpose, farming of iguanas has become an economicalattractive alternative to cattle farming and a signi!cant source of foodfor local populations.
Two species are farmed for producing meat for human consump-tion: the green iguana (Iguana iguana), which is the most popularspecies for farming, and the black iguana (Ctenosaura spp.). Iguanareproduction occurs in captivity as eggs are laid in arti!cial nests,which increases the survival rate of hatched eggs to 90% and morecompared to 50% in the wild. Hatchlings are raised on farm until theyare 6–10 months old, then they are released into forested areas closeto the farms until they are of marketable size. This takes about twoyears. Iguanas are herbivorous, and in the wild they feed primarily onleaves, "owers and fruits.When farmed, they are fedwith amixed diet(“iguana chow”) consisting of broken rice, animal protein (meat, boneand !sh meal), fruit (e.g. papayas, mangos, bananas, avocados), leavesand "owers.
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2.3. Testudines
Although the generic terms “turtle” and “chelonian” may be usedfor all members of the order Testudines, different names are usuallyused for turtles that live in different habitats: terrapins are freshwaterturtles that live in fresh and brackish waters (rivers, pond, lakes),while tortoises are land-dwelling species, and sea turtles (also knownas marine turtles) inhabit marine waters. Most information concern-ing farmed species for meat production refers to terrapins.
Several terrapin and turtle species are commercially reared formeat, including (most importantly) the Chinese soft-shelled terrapin(Pelodiscus sinensis) which is farmed in China, Japan, Thailand,Malaysia, the diamondback terrapin (Malaclemmys terrapin) in theUS, and the green sea turtle (Chelonia mydas) in the Cayman Islands,Suriname, Japan and Réunion. The green sea turtle is also farmed forleather and decorative products. The soft-shelled terrapin and thediamondback terrapin compete on the market with the wild-caughtanimals (Wood, 1991). In general, hard-shelled turtles are lessattractive for farming, in comparison with soft-shelled terrapins, dueto their slow growth.
2.3.1. Soft-shelled terrapinsSoft-shelled terrapins inhabit warm ponds, marshes, lakes and
rivers and feed on crustaceans (e.g. crabs, shrimps) as well as small!sh and snails. They grow to a maximum of 5 kg and can live for morethan 50 years. Animals over 8 years are used as parents and are onlyobtained from cultivated sources. Mating takes place in May to Juneand females spawn 3–4 times each year laying clutches of eggs inspecially designed sandy pens. Eggs hatch after 50 to 60 days andnewly hatched terrapins are 3–4 g and take about three years to growto 500 g when they are ready for market. The animals are cultured infreshwater ponds 3–33 m2 with sandy beds with water to a depth of20–40 cm and are segregated on size since cannibalism is common.Ponds are oxygenated by inclusion of algae (Microcystis spp.) andunless heated, induce the animals to hibernate in the winter. Theyounger animals are fed mainly with water "eas and polychaeteswhich propagate naturally in the pond. Larger animals are fed withsolid food (shrimp, boiled egg, minced !sh, meat and speciallyformulated feeds) placed on a ramp outside the water. Sulphona-mides, antibiotics and vaccines can be added to the feed (Ikenoue andKafuku, 1992a).
The Chinese soft-shelled terrapin (P. sinensis) is cultivated in Japan,Korea, China, Taiwan, Thailand, Malaysia, Vietnam and Indonesia. Lakeand river turtles are also cultivated in Japan, Taiwan, and Korea formeat for human consumption (Silpachai, 2001). The largest produc-tion is of soft-shelled terrapins, 94% of which exports come fromSouthern China. However this is a growing market: for example, theproduction of soft-shelled terrapins in Taiwan grew from 22 to3782 tons between 1992 and 1998, in China from 4400 tons to92,000 tons between 1993 and 2000 and in Japan from 25 to 700 tonsbetween 1970 and 1990 (Ikenoue and Kafuku, 1992a; Li, 2001;Silpachai, 2001). The popularity of the Chinese soft-shelled terrapinsfor commercial farming depends on many characteristics, such as itsrapid growth rate and high annual reproductive output, the consumerinterest and the wide experience on the condition of its farming(CITES, 2003). Harvest of soft-shelled terrapins occurs by a number ofdifferent routes including transport of live animals, or on farm killing.The carcasses are processed and the meat can be frozen or canned.Recycling of carcass residues is likely.
2.3.2. Sea turtlesArti!cial hatching and rearing of several species of marine turtle is
practiced invarious tropical regions, almost exclusively for conservation.However, there is certainly a tradition of meat production from thegreen sea turtle (C. mydas) in different parts of the world such as in theGrand Cayman Island, Réunion and in the Ogasawara Islands of Japan.
Hawksbill turtles (Erethmochelys imbricata) are also farmed, althoughglobally in smaller number. Although a completely closed aquaculturesystem has been attempted, an ‘Ocean Pasture Plan’ was described byIkenoueandKafuku (1992b). This involved either collectionof eggs fromthewild where the eggs are laid in unfavourable conditions (andwherea high level of mortality occurs) or the catching of mature adult femalesand placing them in breeding ponds adjacent to arti!cial nestinggrounds. Hatchlings are collected and the animals are raised in large,well aerated seawater tanks and fed on pelleted sea turtle food (“turtlechow” formulated with ideal rations of !ber, fat, protein and nutrients)as well as on !sh, !sh offal, squid, seaweed, and vegetables. Turtles aregrown to 40 kg after about 2 years (fully grown adults are about 200 kg)and slaughtered on farm. Themeat and internal organs are frozen,whilethe plastron is processed into the ingredients for canned turtle soup. Thecarapace, skin and scutes are processed for ornaments (Ikenoue andKafuku, 1992b). Export of meat from sea turtles is prohibited under theCITES Treaty. The meat can be consumed only by the local populationand is sold in the domestic market.
3. Biological hazards
This section deals with biological hazards for which there isevidence for a demonstrable public health risk from consumption ofreptile meat.
3.1. Bacteria
3.1.1. Salmonella spp.Salmonella spp. are considered the major bacterial hazard that may
occur in reptilemeat since this genus of bacteria occurs as commensalsof their intestinal "ora (Minette, 1984; Zwart et al., 1970). Intestinalcarriage rates of salmonellae exceeding 50% in asymptomatic reptileshave been reported (Chiodini and Sundberg,1981; Geue and Loschner,2002;Woodward et al., 1997). Although the occurrence of salmonellaein reptiles kept as pets (mainly iguanas, turtles, and snakes) or farmedfor the supply of the pet market has been repeatedly documented inthe US (CDC, 1992a,b, 2003, 2007) and in Europe (Geue and Loschner,2002; Schroter et al., 2004), limited information is available about thepresence of salmonellae in reptiles, other than crocodilians, farmed forthe production of meat for human consumption. Studies on salmo-nellae in crocodiles are few, but consistently report a very commonoccurrence of a great number of serotypes in clinically healthy farmedas well as in wild crocodiles (Madsen et al., 1998; Manolis et al., 1991;Obwolo and Zwart, 1993; van der Walt et al., 1997). The rates ofintestinal carriage of Salmonella spp. have been reported as 16–27%,and the identi!ed serotypes cover a broad range within S. entericasubspecies enterica, salamae, arizonae and diarizonae. Salmonellaewere recovered from cloacal swabs collected from 4 out of 29 farmedalligators and from 2 out of 71 wild alligators in Texas and Louisiana(Scott and Foster, 1997). Salmonella was also detected in 8 out of 20hatchlings, 3 out of 20 adults and 7 out of 16 egg surfaces of farmedgreen iguanas in El Salvador (Mitchell and Shane, 2000).
Studies on crocodile meat (Madsen,1993, 1996; Manolis et al., 1991)have documented the common presence of salmonellae in both freshchilled and frozen meat for human consumption. In Australia,salmonellae were recovered from 16% of fresh carcasses of farmed C.johnstoni and C. porosus, while similar studies on fresh and frozen meatof farmed C. niloticus in Zimbabwe revealed recovery percentages of 20–33%. Serotype distribution showed a great variety within S. entericasubspecies enterica, salamae and diarizonae. Although many of theseserotypes may be considered as types rarely or never associated withhuman disease, 40% or more of isolates belong to subsp. enterica, whichcomprises potential human pathogens, e.g. S. Typhimurium and S.Enteritidis. Limited data are available on the presence of Salmonella spp.in the meat of other reptilians. Salmonella Chester has been isolated inAustralia frommarine turtlemeat (O'Grady and Krause,1999) andmore
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recently, S. Typhimurium was isolated in Japan from snapping turtlemeat (Fukushima et al., 2008). Salmonellae isolated from alligator meatin Florida have been recently typed as S. Anatum and S. Baildon (Xiaet al., 2009).
Salmonella contamination of crocodile meat occurs on the surfacealthough no quantitative data are available. This contamination is dueto the common intestinal carriage of Salmonella spp. (Chiodini andSundberg,1981; Foggin,1987;Madsen et al., 1998;Manolis et al., 1991;Obwolo and Zwart, 1993; Zwart et al., 1970), and the resulting highcrocodile pond water concentrations of Salmonella spp. (Madsen,1994), both of which act as important sources of meat contaminationduring slaughter and dressing. There is a high degree of handlingduring skinning, where great care is taken to avoid damage to thevaluable skin and consequently less attention is paid to possiblecontamination of the meat (Madsen et al., 1992). Since high rates ofintestinal carriage of Salmonella spp. often occur among reptiles, in theabsence of qualitative and quantitative data, it is likely that meat fromspecies other than crocodiles presents a similar hazard.
Cases of human salmonellosis (due to S. Montevideo, S. Thompson,S. Paratyphi B and S. Typhimurium) have been reported in Japanfollowing consumption of raw blood, viscera and raw meat as well ascooked meat of the soft-shelled terrapin Trionyx sinensis japonicus(Fukushima et al., 2008; K. Kubota, National Institute of Health Sciences,Tokyo, personal communication). An outbreak of salmonellosis with 36human cases occurred in 1998 in an Aboriginal community in NorthernAustralia after consumption of the meat of a green sea turtle, which is apopular food source in coastal communities in the Paci!c (O'Grady andKrause,1999). The potential for contamination of other reptile species isillustrated by cases of systemic infection (some of which were fatal) bySalmonella enterica subsp. arizonae in the US following consumption ofdried rattlesnake meat used as a medicinal product among Hispaniccommunities (Bhatt et al., 1989; Kelly et al., 1995; Riley et al., 1988;Waterman et al., 1990). No information has been provided as to theorigin of the meat, either from a wild or farmed rattlesnake.
3.1.2. Vibrio spp.Turtles and terrapins and water from their breeding pools have
been identi!ed as the samples most contaminated by Vibrio choleraein an investigation on 12,104 seafood and aquatic products from 12provinces of China (Zhang et al., 2007). Cholera toxin producing V.cholerae (non-O1) and Vibrio mimicus were also detected in soft-shelled terrapins in Japan (K. Kubota, National Institute of HealthSciences, Tokyo, personal communication).
Consumption of raw eggs from Olive Ridley sea turtles (Lepidochelysolivacea) was associated with an outbreak among 33 hospitalisedpatients with severe diarrhoea associated with cholera toxin producingV. mimicus in Costa Rica (Campos et al., 1996). V. mimicus was alsoisolated from the sea turtle eggs collected both from a market anddirectly from the wild (Campos et al., 1996).
3.1.3. Other bacteriaMost published information about bacterial genera other than
Salmonella and Vibrio refers to their detection in reptiles kept as petsor in zoos. Although some of those genera (e.g., Aeromonas, Myco-bacterium, Chlamydia) have been also isolated fromwild, captive and/or farmed reptiles (Ariel et al., 1997; Gorden et al., 1979; Huchzer-meyer et al., 2008), there are limited or no data concerning theirpresence in reptile meat and other products (Madsen, 1993, 1996).Consequently, the relevance of such bacterial genera for public healthfollowing consumption of reptile products is considered very low oreven negligible.
3.2. Fungi
Super!cial or systemic fungal diseases have been reported incaptive reptiles (Cheatwood, 2000), however mycoses in free-living
reptiles are rarely recognized. Skin mycoses are not relevant in aperspective of reptile consumption, therefore only deep-seatedmycoses are considered here. Deep-seated mycoses are usually nottransmissible among animals, except for pneumocystosis, which is astrictly host-species speci!c mammalian infection (Dei-Cas et al.,2006). Reptiles, like humans, usually acquire deep-seated fungalinfections from the soil, which is the major reservoir. Although severalfungal species involved in reptilian deep-seated mycoses can be alsoinvolved in human disease, no risk from reptile products consumptioncould be identi!ed.
Microsporidia, which were recently assigned to the group of Fungi,are recognized pathogens of reptiles, especially for weakened animals(Graczyk and Cran!eld, 2000). Microsporidian species pathogenic tohumans have not been identi!ed in reptiles hitherto, and no datasuggesting microsporidiosis transmission from reptiles to humanshave been reported to the authors' knowledge.
3.3. Parasites
3.3.1. Protists and related eukaryotic microorganismsReptiles host a variety of enteric unicellular pathogens, including
those in the genera Blastocystis, Cryptosporidium, Eimeria, Entamoeba,Giardia and Isospora, as well as blood Apicomplexa (Hepatocytozoonspp., Haemogregarina spp.) (Bhattacharya et al., 1988; Ladds and Sims,1990; Lainson et al., 2003; Noel et al., 2005; Upton and Zien, 1997;Xiao et al., 2004). However, the majority of these protozoa are speci!cfor reptiles and are of no public health importance.
Xiao et al. (2004) detected Cryptosporidium parvum and Cryptos-poridium muris (both human pathogens, the latter very rarelyreported) in the faeces of lizards and snakes, but they concludedthat the parasites had probably infected the rodents ingested by thosecarnivorous reptiles. Cysts or oocysts from other protozoan parasites(including the above mentioned, plus additional species such as Tox-oplasma gondii and Cyclospora cayetanensis) may contaminate reptilemeat if harvested from water contaminated by other animals' faeces.As to the tissue cysts of T. gondii, they are not found in reptile meat,since the life cycle of the parasite is restricted to warm-bloodedanimals (mammals and birds). In conclusion, reptile meat has notbeen implicated with transmission of protozoa to humans.
3.3.2. MetazoaCestodes, acanthocephalans, nematodes, leeches, pentastomids and
arthropods are frequently found parasitizing reptiles, some of which(e.g. cestodes, nematodes, and pentastomids) are pathogenic to theirreptile hosts (especially under captive conditions) and can betransmitted to humans. This is the case for sparganosis and pentasto-miasis that can be contracted by humans through snake meatconsumption (Dei-Cas, 1996), and for trichinellosis which can developafter ingestion of meat from monitor lizards, and possibly from otherreptilians (crocodiles).
3.3.2.1. Cestodes: Spirometra. Spirometra is a genus of pseudophylli-dean cestode tapeworms that reproduces in canines and felines(de!nitive hosts) and requires two intermediate hosts (Beaver et al.,1984). The !rst intermediate host is a copepod (planktonic crusta-cean) of the genus Cyclops which ingests the coracidium (free-living,ciliated embryos) that develops from Spirometra eggs in watercontaminated with the faeces from infected de!nitive hosts. In thetissues of the copepod, the coracidium turns into the !rst-stage larva,or procercoid. When a second intermediate host ingests an infectedcopepod, the procercoid develops into a second larval form, theplerocercoid or sparganum. The plerocercoid larva can be harbouredby many vertebrates, including amphibians, reptiles, birds, smallmammals (rodents and insectivores), humans, other primates, andswine which may function as paratenic or transport hosts by feedingon animals infected with encysted plerocercoids that pass through the
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intestinal wall and migrate to other tissues (Denegri and Reisin, 1993;Khahil et al., 1994). In the intestine of the de!nitive hosts, theplerocercoid or sparganum attaches to the mucosa where it maturesinto an adult cestode of about 25 cm length (in the case of S.mansonoides) within 10 to 30 days. The adult cestode generally doesnot affect the health of the host, but in cats it may produceweight loss,irritability, and emaciation, together with an abnormal or exaggeratedappetite (Hendrix, 1995). The infection of the second intermediatehost by plerocercoid or sparganum can be clinically apparent whenthe number of ingested larvae in the intestinal tract is large andespecially when they invade other organs (Acha and Szyfres, 1994).
Spirometra is found throughout theworld. Infections in the Far Eastare due to plerocercoid larvae of S. mansoni, in the United States to S.mansonoides, in Europe to S. europaei, in Africa to S. theileri, and inAustralia to S. erinacei. However, the identi!cation of Spirometraspecies can be dif!cult and the taxonomy is uncertain. Among reptiles,snakes are important intermediate hosts. For example, 91% of 1240snakes captured between 1980 and 1988 in Ehime Prefecture, Japan,were infected with S. erinacei (Sato et al., 1992). In another study, S.mansoniwas recovered in 61% of 100 snakes from 11 of 13 localities ofsouthern Korea examined during 1981 and 1982 (Cho et al., 1982).Snakes also play the most important role, in regard to reptile meat, asinfection source for acquiring sparganosis.
The majority of human foodborne sparganosis cases have beenrecognized following the consumption of undercooked meat of eithersnakes or frogs. Sato et al. (1992) reported that the number ofplerocercoids collected from snakes ranged from 0 to 427 per snakewith a median of 12 (for Elaphe quadrivirgata), and from 0 to 130 witha median of 9 (for Rhabdophis tigrinus tigrinus). The parasite burden insnakes increased with age, and it was suggested that E. quadrivirgatahad more parasites than R. tigrinus tigrinusmainly because the formerhad a longer life span. Although freezing of snake meat wouldprobably destroy plerocercoids, there is no data on the appropriatetreatment to prevent foodborne sparganosis from consumption ofsnake meat.
In crocodile meat, S. erinacei was detected in Australia in 1987 inthe meat of two freshwater crocodiles (C. johnstoni) (Bodger andGoulding, 2003; Melville, 1988), and spargana were also found in themeat of dwarf crocodiles (Osteolaemus tetraspis) at markets in theDemocratic Republic of the Congo (Huchzermeyer, 1997). However,Spirometra larvae have not been found in more recently farmedcrocodiles, which may be due to changes in the management systemssince the parasite was !rst identi!ed. Although gourmet restaurantsusually prefer fresh (chilled) rather than frozen meat, crocodile meatmust be frozen to eliminate the risk of tapeworm (S. erinacei)infection (Bodger and Goulding, 2003). As an example, according tothe Australian regulation for the export control of !sh and !shproducts (Federal Register of Legislative Instruments F2006C00346),the meat of a crocodile exposed to or suspected of being infested by S.erinacei must (a) immediately after processing be placed in arefrigeration chamber and (b) be held at a temperature of minus12 °C or cooler at the thermal centre for a minimum of 5 days; orsubjected to such other temperature controls that achieve thedestruction of all viable S. erinacei in the crocodile meat. In the lattercase, the applicable approved arrangement must validate that: (a) thealternative temperature controls will be achieved; and (b) the way inwhich the controls are to be applied will be ef!cient to destroy allviable stages of S. erinacei in the crocodile meat. In this way, the risk ofsparganosis after consumption of crocodile meat is negligible.
Human sparganosis is caused by the ingestion of procercoid larvaefrom un!ltered water contaminated with copepods harbouring theparasite (Cho et al., 1975), or by the ingestion of plerocercoid larvae inraw or insuf!ciently cooked meat of reptiles (or amphibians), or bytraditional medicine remedies, e.g. by topically applying snake or frogskin as poultices to eyes which can result in ocular sparganosis (Choet al., 1975; Min, 1990). Sparganosis cases are reported world-wide,
but they are more common in Asia, particularly in Korea, China, Japan,Taiwan, Vietnam, and Thailand (Beaver et al., 1984). In Korea, 3 humancases were reported for the !rst time in 1924 (Kobayshi, 1925), butmore than 100 caseswere subsequently documented before the end ofthe '80s (Min, 1990).
Foodborne sparganosis cases have been traced to the consumptionof snake meat but not to crocodiles, lizards or turtles. Plerocercoidlarvae have the ability to migrate to any part of the human body (Choet al., 1975; Min, 1990), including the brain (Anders et al., 1984) andthe oral cavity (Iamaroon et al., 2002). However, based on the analysisof 135 cases reported in the Republic of Korea up to 1987, preferredsites include the abdomen (38 cases; 28.1%), urogenital organs (30;22.2%), extremities (24; 17.8%), central nervous system (16; 11.9%),chest (14; 10.4%), the orbital region (11; 8.1%) and breast (2; 1.5%)(Min, 1990).
The incubation period of sparganosis is not well de!ned, and theparasite is thought to live up to 20 years in the human host. Clinicalsigns of sparganosis vary according to the tissues and organs intowhich the parasite migrates, and the deriving in"ammation and painmay persist after the death of the sparganum. When the sparganuminvades the subcutaneous tissue, a nodule will form under the skin,and the lesion will be usually referred to as “creeping tumor” due tothe parasite migrating to other sites through the tissues. A severelypainful lesion may develop in case of in"ammation and edema of thetissues around the eye.
Seroepidemiological observations in the normal adult populationand in epileptic patients revealed prevalences of 1.9% and 2.5%,respectively, in Korea (Kong et al., 1994). Ultrasonographic !ndingsmay also be useful for the pre-operative diagnosis of breast or otherorgans sparganosis (Cho et al., 2000; Kim et al., 2005).
3.3.2.2. Nematodes: Trichinella. Nematode worms belonging to thegenus Trichinella have a very broad range of host species (mammals,birds and reptiles) including humans. They have been detected in allcontinents except Antarctica (Pozio, 2007b). Natural Trichinella infec-tions have been reported in more than 100 species of mammals, sevenavian species, and three reptile species (Pozio, 2005). At present,12 taxawith eight species and four genotypes are recognized in the genusTrichinella, namely Trichinella spiralis (T1), T. nativa (T2) and its relatedgenotype Trichinella T6, T. britovi (T3) and its related genotype Trichi-nella T8, T. pseudospiralis (T4), T. murrelli (T5) and its related genotypeTrichinella T9, T. nelsoni (T7), T. papuae (T10), and T. zimbabwensis(T11) (Pozio, 2007a). Trichinella T12 is a new genotype recentlydetected in a mountain lion from Argentina (Krivokapich et al., 2007).Since all taxa are morphologically indistinguishable at all develop-mental stages, only biochemical or molecular methods can reliablyidentify the genotype of the parasite (Pozio and La Rosa, 2003).
The life cycle of this viviparous nematode parasite includes twogenerations in the same host. After ingesting the meat of an infectedhost, !rst-stage larvae are released following gastric digestion in thenew host, subsequently reach the duodenum and, while embedded inthe intestinal mucosa, undergo four moults to develop into the adultstage within 2 days. Following mating of male and female larvae, thefemales start to deliver newborn larvae 5 to 7 days post infection.Newborn larvae migrate directly into lymphatic and blood vessels ofthe host, subsequently penetrate into striated muscle cells by the useof a stiletto apparatus and lytic enzymes, and develop to infectivemuscle larvae as early as 17 days post infection (Capo et al., 1998).Larval metabolism is basically anaerobic which favors the survival ofthe parasite in decaying tissues (Despommier, 1990), where hypobio-tic !rst stage larvae are maintained until they are ingested by a newhost. Within several weeks, an immune mediated host responseaffects the viability of the adult parasites, which results in theirexpulsion from the intestine (Pozio, 2007a).
Genetically and biologically, Trichinella species and genotypes areclassi!ed into two distinct clades, with the main criterion being the in
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vivo presence or absence of an intramuscular collagen capsulesurrounding the parasite (Zarlenga et al., 2006). One clade comprisesall species that encapsulate in host muscle tissue of mammals only (T1to T9, and T12), while the other one includes those worms that do notencapsulate after muscle cell invasion and that can also occur in birds(T4) and reptiles (T10 and T11) (Pozio and Murrell, 2006).
Data from several studies suggest that body temperature in thehost plays a key role for the infectivity of Trichinella. According toresults from experimental infections in mammals, birds and reptiles,the non-encapsulated species T. papuae and T. zimbabwensis candevelop at temperatures ranging from 26 °C to 40 °C, in both cold- andwarm-blooded animals (i.e. reptiles and mammals). In comparison,the non-encapsulated species T. pseudospiralis can develop at 37 °C to42.5 °C (i.e. mammals and birds), and all of the encapsulated speciesare adapted to a body temperature of 37 °C to 40 °C (i.e. mammals)(Pozio et al., 2004a). Therefore, experimental infections of reptilessuch as Texas horned lizards (Phrynosoma cornutum) and commoncaimans (Caiman sclerops) with T. spiralis, which is well adapted to thebody temperature of warm blooded animals except birds, were notsuccessful at their usual activity temperature of 20 °C to 28 °C (Jordan,1964; Kapel et al., 1998), but conversely 1 month post infection, viablelarvae were recovered from lizards when kept at 37 °C (Jordan, 1964).
In 1995, Trichinella was detected for the !rst time in farmed Nilecrocodiles (C. niloticus) in Zimbabwe (Foggin et al., 1997). At this time,out of 29 farms examined, 18 (62.1%) were positive for Trichinellamuscle larvae with 256 (39.1%) out of 648 animals being infected. Thefeeding of meat from other crocodiles slaughtered at the farms wasidenti!ed as a potential infection source. Although a program for thecontrol of Trichinella was established, 11 (40.7%) of 27 farms inZimbabwe had infected crocodiles 7 years later (Pozio et al., 2007).Studies on the etiological agent revealed a new non-encapsulatedspecies, namely T. zimbabwensis, which infects both poikilothermicvertebrate species and mammals including primates (Pozio et al.,2002). Later studies were conducted in wild monitor lizards (Varanusniloticus) and wild Nile crocodiles in Zimbabwe and Mozambique,respectively. T. zimbabwensis was found in 5 (17.6%) of 28 monitorlizards from an area close to a crocodile farmwhichwas known to rearinfected crocodiles. In one monitor lizard from Victoria Falls, the larvalburden ranged from 4 to 8.3 larvae per g of examined muscles. In 8(20%) of 40 crocodiles from Zimbabwe and in one farmed crocodilefrom Ethiopia, non-encapsulated larvaewere identi!ed. Larval densityin muscle samples of four examined wild crocodiles from Zimbabweranged between 2 and 42 larvae per g (Pozio et al., 2007).
After discovery of the non-encapsulated species T. papuae in wildand domestic pigs in 1999, 46 farm- and 72 wild-borne saltwatercrocodiles (C. porosus) from Papua New Guinea were tested for Tri-chinella. Whereas all farm-borne crocodiles were negative, 16 (22.2%)wild-borne crocodiles were positive for T. papuae with an averagelarval burden of 7 larvae per g of muscle (Pozio et al., 2004a).
Besides !eld studies in reptiles, experimental infections havedemonstrated that other reptile species, especially caimans (C.sclerops) and varans (Varanus exanthemicus), and to a lower degreeturtles (Pelomedusa subrufa) and pythons (P. molurus bivittatus) aresusceptible to T. zimbabwensis and T. papuae (Pozio et al., 2004b).After inoculation of 3000 larvae per animal, the average larval burdenfor T. zimbabwensis was 1, 7, 15 and 589 larvae per g in the muscles ofpythons, turtles, caimans and varans, respectively, while for T. papuae,the larval density calculated for the aforementioned reptile specieswas 0.5, 8, 30 and 1074 larvae per g, respectively.
Since both T. zimbabwensis and T. papuae can be easily transmittedto mammals, the discarded parts of crocodile carcasses should beproperly destroyed to avoid infection of synanthropic animals, and thewaste products should not be fed to domestic animals unless the meatis frozen or cooked before use (Pozio et al., 2004b).
Contrary to animals, where susceptibility to natural infection canremarkably vary depending on the Trichinella species involved, humans
are highly susceptible to infection with several Trichinella species andgenotypes. Thus, although trichinellosis cases havenotbeen reported forall species and genotypes so far, all trichinellae are considered to bepathogenic for humans. Whereas infections with few Trichinella larvaecan remain asymptomatic, higher larval burdens can cause gastro-intestinal as well as generalized clinical signs and symptoms such asfever and myalgia which are directly related to the development of theparasitic cycle in the human host. A minimal infectious dose of 100 to300 larvae can cause clinical disease in humans (Dupouy-Camet andBruschi, 2007). Differences as to signs, symptoms, and clinical coursehave been observed, but it is not known whether they are due to thedifferent Trichinella species and genotypes involved (Bruschi andMurrell, 2002; Dupouy-Camet and Bruschi, 2007).
Trichinellosis in humans is associated with the consumption of rawor undercooked contaminated meat. Consumer habits such as theconsumption of traditionally prepared food based on raw or under-cooked meat or derived products play an important role in theepidemiology of the disease. Conversely, when a population uniquelyconsumes well cooked meat, trichinellosis cases are lacking or veryrare, despite a persisting transmission among wildlife (Pozio, 2007b).Till now, only two human trichinellosis outbreaks due to the con-sumption of reptile meat from a monitor lizard (Varanus nebulosus)and a turtle (unidenti!ed species) have been documented in Thailand(Khamboonruang, 1991), possibly due to infection with T. papuae,although the involved nematode species could not be con!rmed(Pozio et al., 2007).
Since meat of reptiles may be infectious for humans, speci!ccontrol measures have been implemented for consumer protection.Several countries including Australia prescribe the systematic inspec-tion of crocodile meat for Trichinella larvae (Anonymous, 2000a).According to the legislation of the European Union, namely Regulation(EC) No. 2075/2005, all reptile meat intended for human consump-tion has to be examined for Trichinella larvae with one of the approvedmethods (European Community, 2005).
Meat of reptiles not subjected to Trichinellameat inspection shouldbe processed using methods recommended by the InternationalCommission on Trichinellosis (ICT) in order to inactivate the parasite(Gamble et al., 2000). Freezing is an ef!cient method to kill the larvae,if the meat is frozen for 20 days at !15 °C (5°F), 10 days at !23 °C(!10°F), or 6 days at!29 °C (!20 °F), provided that the meat is lessthan about 15 cm (6 in.) thick. Cooking is another post-harvestprocessing method for inactivating muscle larvae. The ICT recom-mends that fresh meat should be cooked to an internal temperature ofat least 71 °C (160°F). Inactivation of Trichinella larvae can depend onseveral factors such as salt concentration, moisture, and temperature,hence consumer protection by salting, drying, smoking, or preservingcrocodile meat is not reliable (Gamble et al., 2000).
3.3.2.3. Nematodes: Anisakidae. Ascaridoidea nematodes of thefamily Anisakidae, genera Contracaecum, Anisakis and Pseudoterranovaare intestinal parasites from !sh-eating birds, Cetaceans (dolphins,porpoises, whales) or Pinnipedians (seals, sea lions, walruses),respectively. Females shed undeveloped eggs in host faeces, then eggsembryonate and hatch inwater releasing free-swimming larvae that areingested by crustaceans such as euphausiaceans, decapods, copepodsand amphipods, where they localize within the haemocoel (Chai et al.,2005; Dei-Cas, 1996). De!nitive avian ormammalian hosts may acquirethe infection directly by ingesting infected crustaceans. However,infected crustaceans are more frequently ingested by teleostean !shor cephalopodmolluscs. Predators of infected!sh or cephalopods can inturn get infected and play the role of paratenic or transport hosts.Anisakidae larvae (10–30 mm!1 mm) penetrate the intestines andinvade internal tissues to become the source of infection for de!nitivebird or mammalian hosts or for humans, who constitute dead-endhosts. In !sh, anisakid larvae can be found inside the gastro-intestinaltract, in the pleuro-peritoneal cavity, liver, gonads or embedded in
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muscles (Mudry et al., 1986). These larvae are infectious either tode!nitive hosts (piscivorous birds or mammals) or to other !sh-eatingvertebrates such as larger !sh, sea turtles (Burke and Rodgers, 1982) oreven crocodiles, which are potential paratenic hosts. Ichthyophagousreptiles, like most crocodiles, are probably the most exposed reptiles toanisakid larval infections. Contracaecum larvae have been in factreported in crocodilians (Acha and Szyfres, 1994; Goldberg et al.,1991; Moravec, 2001). These !ndings suggest that consumption of rawor lightly cooked anisakid-infected crocodile meat could causeanisakiasis in humans. The risk to humans could be relatively lowwhen crocodiles are born in farms and fed with arti!cial food or frozen!sh (!20 °C for more than 24 h). Apart from crocodiles, anisakidparasitism does not seem to be usual in reptiles though anisakid larvaehave been also found in the green sea turtle (C. mydas) (Burke andRodgers, 1982).
In humans, anisakid larvae can penetrate the gastric or intestinalwall where they may induce eosinophilic granulomas. In some cases,the larvae migrate to the peritoneal cavity and invade adjacent organs(liver, pancreas) or, more rarely, distant organs (Acha and Szyfres,1994; Dei-Cas, 1996; Mudry et al., 1986). The infection can beasymptomatic or, alternatively, cause disease of varying severitydepending on both the number of larvae and the intensity of thein"ammatory response. Recent works showed that human diseaseassociated with allergic reactions against anisakid larvae also occurs(Daschner et al., 2005), even when larvae are dead. Thus, anisakidlarvae might represent a neglected cause of allergic diseases inEurope. However, despite the occurrence of this parasite in reptiles,human disease has not yet been linked to reptile meat consumption.
3.3.2.4. Other nematodes. Eustrongylides spp. (Nematoda: Diocto-phymatoidea) are intestinal parasites of aquatic birds. Their larvae canbe found in tissues of !sh, amphibians, reptiles and humans. In thesehosts, Eustrongylides larvae (25–150 mm!2 mm) are able to causeintestinal perforation (Eberhard et al., 1989), or visceral lesions(Beaver et al., 1984). The zoonotic potential of these larvae, which arefound in crocodiles (Acha and Szyfres, 1994; Fang et al., 1991;Goldberg et al., 1991; Junker et al., 2006) is signi!cant. Fish-eatingcrocodiles and other !sh-eating vertebrates such as water snakes(Bursey, 1986) or humans (Eberhard et al., 1989; Narr et al., 1996) mayacquire the infection from infected !sh. Humans may also becomeinfected by consuming raw or lightly cooked infected reptile meat,though no case has been reported to date.
Gnathostomiasis is a zoonotic parasitic disease caused by larvae orimmature adults of spirurid nematodes of the genus Gnathostoma.Gnathostomiasis is frequent in the Far East, especially in Japan andThailand, but it was also reported in Mexico and Central America(Ligon, 2005). Two species are most frequently involved: G.spinigerum, from domestic or wild felids, and G. hispidum from wildboar and pigs (Dei-Cas, 1996). However, two other species have anincreasing impact in humans in Japan (Nawa, 1991): G. nipponicumand G. doloresi. G. hispidum larvae were recently reported from thepit-viper Agkistrodon brevicaudus in Korea (Sohn and Lee, 1998).Gnathostomiasis is usually contracted by ingestion of raw or lightlycooked food prepared from freshwater !sh, frogs, snakes, birds ormammals. The disease in humans includes a great variety of clinicalmanifestations caused by cutaneous and/or visceral larva migranssyndrome. The development of a cutaneous super!cial or creepingeruption, and a migrating erythema, is common. Among visceralinvolvements, neurological forms can be associated with signi!cantmorbidity and mortality (Ligon, 2005). A human case of G. doloresiinfection with the clinical presentation of colonic ileus has beenreferred to the consumption of meat of the snake Agkistrodon halys(Seguchi et al., 1995).
3.3.2.5. Crustaceans: Pentastomids. Previously included among the“Pararthropoda”, pentastomids (70 species, mostly parasites of reptiles)
were recently assigned to the Crustacean group of Maxillopoda, whichincludes also copepods, cirripeds, ostracods and other organisms(Lecointre and Le Guyader, 2001). Pentastomids are worm-likearthropoda, also known as ‘tongue worms’, measuring 1–10 cm length(with females larger than males) that dwell in the rhino-pharynx andsinus cavities of snakes, crocodiles and numerous wild or domesticcarnivorous mammals (Dei-Cas, 1996).
Armillifer life cycle involves transmission between snakes (de!ni-tive hosts) and their prey, i.e. rodents (intermediate hosts). Eggscontaining the infective larva or nymph are shed by adult pentasto-mids in the upper respiratory tract of the snake, and are disseminatedin the environment by sneezing, expectoration or, after swallowing,through the faeces. After ingestion by the intermediate hosts, the egghatches in the gut and releases the nymph that has 4 typical hook-shaped appendices. The nymph can then pass through the intestinalwall and invades abdominal or thoracic organs such as lymphaticnodes, liver, spleen or lungs. Nymphs reach the infectious stage 250–350 days after the infection of the intermediate host (Acha andSzyfres, 1994). They measure 5 mm length and are similar to the adultlife cycle stage. When the de!nitive host ingests the nymphs with thetissues of its prey, nymphs leave the stomach andmigrate to the upperrespiratory tract, where they develop into sexually mature female andmales. Mating takes place and females begin egg production.
In crocodiles, two pentastomid families occur: Sebekidae, with thegenera Sebekia, Leiperia, Alo!a, Sel!a and Agema, and Subtriquetridaewith only one genus, Subtriquetra (Anonymous, 2000a). The life cycleof these pentastomids is not well known. Fish may play the role ofintermediate hosts as suggested by the !nding of Subtriquetra larvaein two Cichlidae species (Junker et al., 1998) from South Africa, whichare often predated by the Nile crocodile (C. niloticus). In Northernareas of Australia, pentastomid larvae were identi!ed in the rainbow!sh (Melanotaenia maccullochi) and in perchlets (Ambassis sp.)(Anonymous, 2000a). In the New World, the !sh Gambusia af!nis, awell known predator of mosquito larvae, is the intermediate host of atleast two pentastomid species of alligators (Anonymous, 2000a).
In crocodiles, pentastomids can cause either sub-clinical infectionor severe disease (Buenviaje et al., 1994). Tissue migration of nymphsand encysting of larvae in different organs and muscles can inducemild or severe lesions according to the number of parasites, hostsusceptibility and occurrence of other underlying diseases. The adultpentastomids are able to cause severe lesions, and even to go acrosslung tissue and to reach the skin surface through the thoracic wall(Anonymous, 2000b). These parasites can cause meningitis, pneu-monia and signi!cant mortality, especially in young crocodiles incaptivity. If no intermediate !sh hosts are introduced into crocodilebreeding farms, the circulation of pentastomids in the breedingfacilities should be self limiting. Conversely, the introduction ofinfected !sh to feed crocodiles in Australian breeding farms wasassociated with the emergence of pentastomiasis (Buenviaje et al.,1994). Crocodiles might however be infected also with pentastomideggs from the environment.
Humans may get infected with pentastomids by ingesting raw orinsuf!ciently cooked snake or crocodilian meat contaminated withthe larval stage of the parasite, or by ingesting infectious eggs thatcontaminate the carcasses of infected reptiles, water or food(Anonymous, 2000a; Dei-Cas, 1996). Human pentastomiasis is usuallycaused by Armillifer species (A. armillatus, A. grandis in sub-SaharanAfrica; A. moniliformis, A. agkistrodontis in Asia) which are parasites ofpythons or other snakes, or by Linguatula serrata that parasitizes nasalcavity, frontal sinuses and eardrum cavities of dogs, other canids andfelids. Infection by Armillifer spp. is surely frequent in Africa,particularly in the Republic of Congo, but it is usually asymptomatic.The Armillifer nymphs are preferentially found in the intestinalmucosa, peritoneal cavity and liver (du Plessis et al., 2007), althoughspleen, lungs and conjunctiva can be also affected. The infection,usually asymptomatic, can be discovered incidentally at the time of a
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surgical intervention (Tappe and Büttner, 2009). Clinical diseaseoccurs when eyes are invaded or if nymphs cause intestinal occlusion.Fatal forms are unusual (Yapo Ette et al., 2003). The histologicalexamination of visceral lesions can reveal the nymphs surrounded bya granulomatous tissue with eosinophilic abscesses (Dei-Cas, 1996).Lesions often evolve towards calci!cation.
3.4. Viruses
There are several speci!c viral diseases of reptiles which are nottransmissible to humans. Huchzermeyer (1997) reported that no viralagent has been recognized as transmissible from crocodilians tohumans. Experimental data suggest that turtles and lizards can beoverwintering reservoirs of some arboviruses that are infectious tohumans, such as the Eastern Equine Encephalitis (EEE) virus, theWestern Equine Encephalitis (WEE) virus and the Japanese Encepha-litis (JE) virus (Bowen, 1977; Doi et al., 1983; Oya et al., 1983; Smithand Anderson, 1980). In addition, two epizootics due to West NileVirus (WNV) infection occurred in 2001 and 2002 among captiveAmerican alligators (A. mississippiensis) in the US (Miller et al., 2003),and WNV infection was reported in Nile crocodiles reared in acommercial farm in Israel (Steinman et al., 2003). However,arboviruses have not been shown to be transmissible to humansthrough consumption of meat of infected reptiles, thus the derivingpublic health risk is considered to be negligible.
3.5. Prions
The prion protein is a normal cellular protein (PrPc) exhibitingunique properties, due to its ability of adopting an abnormalconformation (usually abbreviated as PrPsc, sc from scrapie, theprototype animal TSE) that is associated with transmissible spongi-form encephalopathies (TSEs) or prion diseases in humans andanimals. PrPsc is the main if not only constituent of the infectious TSEagents or prions. The appearance of a prion disease in cattle (bovinespongiform encephalopathy, BSE) and its transmission to humans,causing variant Creutzfeldt-Jakob disease (vCJD), discloses potentialimpact for food safety if similar events would occur in reptiles.
Currently there are no indications that natural TSEs occur inreptiles. However, this is based on no or very limited data. Data on PrPsequences are only available in one reptile species, the turtle(Trachemys scripta), indicating an identity degree to mammalianprion proteins of about 40% (Simonic et al., 2000), suggesting a highspecies barrier for transmission of mammalian prions to reptiles.
Mammalian products are frequently fed to carnivorous reptiles,hence intra-species and intra-order recycling via feed could enablemammalian TSE agents to establish themselves in animals currentlybelieved to be not susceptible, including reptiles, and for speciesadaptation of such agents to occur. To this regard and in analogy with!sh, risks may exist, linked to feeding possibly TSE-contaminatedfeeds to animals currently believed to be not susceptible, includingreptiles. In other words, after eating TSE agents, reptiles might be apossible reservoir of the infectious agent, even if not undergoing anyovert disease.
Feeding experiments in rainbow trout indicate that PrPsc remainedno longer than 15 days in the !sh intestine and did not cross theintestinal barrier. This experimental work shows that there is apotential risk of residual TSE infectivity in !shmeal produced from !shrecently fed with TSE contaminated feed. After oral inoculation ofscrapie prions, mouse bioassay became positive only in one singleintestinal sample one day after infection, while all other organsremained negative up to 90 days after inoculation (EFSA, 2007a,b). Byanalogy with !sh, there is a potential risk of residual TSE infectivity inreptiles acting as temporary carriers when recently fed with TSEcontaminated feed. Experimental workwould be needed to clarify thisissue, however the risk of transmission of TSEs is considered unlikely.
3.6. Biotoxins
The term chelonitoxism refers to an intoxication followingingestion of the "esh of sea turtles (Champetier de Ribes et al.,1997; Fussy et al., 2007; Gatti et al., 2008; Yasumoto,1998). Fussy et al.(2007) listed 34 incidents of chelonitoxism poisoning in theCaribbean, Indian and Paci!c Oceans involving 1880 cases with 267deaths. The hawksbill turtle (Eretmochelys imbricata) and, lessfrequently, the green sea turtle (C. mydas) are the two species mainlyimplicated in this type of food poisoning, but the leatherback turtle(Dermochelys coriacea) and the loggerhead turtle (Caretta caretta)may also be involved. The toxic compounds identi!ed to date as thecausative agents are lyngbyatoxins, which are accumulated throughthe food chain into the "esh of marine turtles following ingestion ofthe cyanobacterium Lyngbya majuscula, that grows on seagrass, sandand rocky outcrops (Osborne et al., 2001). In addition, otherunidenti!ed toxins might also be involved, particularly in carnivoroussea turtles such as E. imbricata. No effect on the health of the sea turtleitself has been reported, but all organs of the animal are potentiallytoxic regardless of the heat treatment, which suggests that the toxin isthermoresistant. In humans, clinical signs due to sea turtle poisoninginvolve the upper digestive tract with nausea, vomiting, epigastricpain, and sometimes diarrhea. General signs such as dizziness, malaiseand sweating may also be observed. Recovery may occur over a weekwithout further signs. Severe cases develop glossitis, dysphagia,drowsiness, multiorgan failure (tubular nephropathy, liver cytolysis,respiratory distress) leading to a coma and to high mortality orneurological sequelae in survivors (Aguirre et al., 2006). Breast-fedchildren may also get poisoned as the toxins pass into milk (Fussyet al., 2007).
4. Exposure assessment
Biological hazards of reptile meat either originate from infection orcontamination of live reptilians or are a secondary result fromcontamination at slaughter or through processing. The application ofGood Hygienic and Good Manufacturing Practices (GHP, GMP) andHazard Analysis Critical Control Points (HACCP) systems, respectively atfarm and slaughterhouse level, is crucial for controlling the hazards. Thedecrease or elimination of hazards in reptile meat may be alsoaccomplished with different results through further processing (e.g.freezing, cooking) or by applying preservative methods (e.g. drying,smoking, curing). Adequate cooking is effective for inactivating bacteriaand parasites. Freezing will not inactivate bacteria, but is likely to killSpirometra spp., Trichinella spp. and pentastomids, however there isincomplete information on the effectiveness and optimal treatments fordifferent parasites or reptile species. Spirometra spp. and Trichinella spp.are killed in crocodile meat if speci!ed temperature–time combinations(e.g.!12 °C for at least 5 days) are applied. There is no information as tofreezing conditions for inactivating pentastomids in reptile meat. Theeffect of drying, smoking and curing for inactivating bacteria andparasites in reptilemeatwill differ according to the speci!ed parametersof the treatments. Cooking or freezing is unlikely to inactivate marinebiotoxins occurring in sea turtles.
Reptiles are an important source of protein for human populationsin many parts of the world other than Europe and North America,where consumption is comparatively much lower. In Europe, there islimited tradition of reptile meat consumption, although there havebeen examples in the past of consumption of some species, such as theOcellated lizard (Timon lepidus) in some parts of Spain up to fewdecades ago, and turtle soup, which was a delicacy in the UK and inother European countries during the 19th and early 20th centuries.
In tropical marine environments, turtles are taken from the wildand their eggs andmeat are consumed in stocks and stews. This is nowless common but still occurs in some parts. Turtle soup is also madefrom the plastron (ventral shell). Soft-shelled terrapin is cultivated
171S. Magnino et al. / International Journal of Food Microbiology 134 (2009) 163–175
andwidely consumed in China, Taiwan, Japan and Korea, either raw orprepared as a soup or as broiled meat. In Japan, terrapin meat, eggsand blood are eaten raw as well as cooked (Campos et al., 1996;Ikenoue and Kafuku, 1992a) and the plastron is boiled and allowed tosolidify in Japan and China. Turtle meat is also popular in Southern US(e.g. Louisiana and Florida).
Snake is widely consumed in the Far East. In the Republic of Korea,consumption of snake meat is viewed as an aphrodisiac and as !eldfood during military survival training (Cho et al., 1974, 1975; Min,1990). Rattlesnake is eaten in Southwestern US (Noel et al., 2005) anddried snake meat and snake meat powders are consumed as aMexican–American folk remedy (Bhatt et al., 1989).
Consumption of crocodile, caiman and alligator meat occursmostly in Australia, Thailand, South Africa and the US, often wherethe meat is a by-product of leather farming of crocodile and alligator(Millan et al., 1997). Iguanas are widely consumed in Central America,where they are often even preferred to other species' meat. Lizards ofvarious species are traditionally consumed by Australian Aboriginalcommunities.
Consumers of reptile meat in Europe and North America mainlybelong to two categories: communities of immigrants with traditionalhabits of eating reptile meat, and customers of gourmet restaurants orspecialty shops that prepare or sell reptile meat as a delicacy. Thepattern of consumption is likely to differ between these twocategories. Imported frozen crocodile, alligator, caiman, rattlesnakeand python meat are now readily available from specialist meatsuppliers in the EU Member States, however since local productionmay occur in the near future for some of these species, freshmeat maybecome available. Reptile meat is consumed in a variety of ways,generally following cooking, although dried and raw meat is some-times consumed. Recipes for crocodile carpaccio can be found in theInternet. The meat is generally consumed as whole pieces althoughprocessed meat may be used for preparing sausages and burgers aswell (Bodger and Goulding, 2003).
5. Conclusions
The consumption of reptile meat and other reptile products occursthroughout the world and probably represents similar biologicalhazards to the consumption of meat of any other animal. These hazardscan occur from pathogenic agents within the meat or other products(including the reptilian enteric tract), or as a result from crosscontamination of food poisoning agents from food contact surfaces orthe meat of other species during slaughter or butchery and processing.Although relatively small in number, reports of food poisoning fromreptile products illustrate their potential to cause diseasewhich is likelyto increase if consumption of these products becomes more common.Reported cases of human disease associated with the consumption offood from reptiles are listed in Table 1. To this regard, it should be notedthat most probably several cases of disease fail to be linked to theconsumption of reptile products and are consequently underreported.
The BIOHAZ Panel of EFSA concluded that risks due to theconsumption of reptile meat are related to hazards caused by certainbacteria (Salmonella spp.) and parasites (Spirometra spp., Trichinellaspp., pentastomids) (EFSA, 2007a). Other hazards related to theconsumption of reptile products are caused by V. mimicus and bymarine biotoxins which may occur, respectively, in eggs and meat ofsea turtles, and by Gnathostoma doloresi that may be found in snakemeat. Although these hazards are well documented in the literature,there is limited knowledge concerning other risks which may arise forhumans after consumption of reptile meat. Apart from farmedcrocodilians, there is limited information related to biological hazardsfrom meat of other farmed reptilians.
Reptiles are well-known reservoirs for Salmonella species, and therisks of getting infected from reptilians kept as pets are well docu-mented. However, there is a lack of information about the presence of
Salmonella spp. in meat from farmed reptilians other than crocodilians.Salmonella spp. constitute a signi!cant public health risk due to thedocumented high intestinal carrier rate in live crocodilians that isre"ected in an equally high contamination rate in their fresh and frozenmeat. Parasites causing sparganosis, pentastomiasis, gnathostomiasisand trichinellosis have been transmitted to humans through consump-tion of contaminated snake meat, and monitor lizard and turtle meat,respectively. Other reptiles, e.g. crocodilians, although found to beparasitized by the above parasites, have not been implicated with theirtransmission to humans through meat consumption.
Conversely, consumption of reptile products may be related tobiological hazards which pose a negligible risk for consumers. Forinstance, infections by fungi, including yeasts, widely occur in reptilesbut have not been linked to the contamination of their meat. Parasiticprotozoa represent a negligible risk for public health after reptile meatconsumption compared to parasitic metazoa. At present, there is noevidence that viruses infecting reptilians can be transmitted tohumans through consumption of reptile meat. Currently there areno indications that natural TSEs occur in farmed reptilians. However,by analogy with !sh, there is a potential risk of residual TSE infectivityin reptiles acting as temporary carriers when recently fed with TSEcontaminated feed.
The feeding of reptiles with non-processed and recycled animalproducts is likely to increase the occurrence of biological hazards inreptile meat. The application of GHP, GMP and HACCP procedures,respectively at farm and at slaughterhouse level is crucial forcontrolling the hazards. Freezing treatment inactivates Spirometraspp. and Trichinella spp. in crocodile meat. However, the effectivenessof freezing for other reptilian meat is unknown.
Acknowledgements
Research for this review was performed by an ad hoc WorkingGroup set up by the BIOHAZ Panel of EFSA. The scienti!c opinion“Public health risks involved in the human consumption of reptilemeat” was published (http://www.efsa.europa.eu/cs/BlobServer/Scienti!c_Opinion/biohaz_op_ej578_reptile_en.pdf) and providescomplementary information to that described here. The authors
Table 1Incidents of infections and intoxications associated with consumption of reptile meatand other products.
Hazard Reptile (food type) Country References
Salmonellaspp.
Soft-shelled terrapin(cooked meat and rawblood, viscera or meat)
Japan Fukushima et al. (2008); K.Kubota, National Instituteof Health Sciences, Tokyo,personal communication
Green sea turtle(partially cookedmeat)
Australia O’Grady and Krause (1999)
Rattlesnake (driedmeat)
USA, Mexico Bhatt et al. (1989); Kellyet al. (1995); Riley et al.(1988); Waterman et al.(1990)
Vibrio mimicus Olive Ridley sea turtle(raw eggs)
Costa Rica Campos et al. (1996)
Spirometraspp.
Snake (raw orinsuf!ciently cookedmeat)
Korea, China,Japan, Taiwan,Vietnam,Thailand
Beaver et al. (1984); Choet al. (1975); Min (1990),Wiwanitkit (2005)
would like to thank the members of the BIOHAZ Panel for theircontribution to this opinion.
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