Parasitism in Southeastern United States

Veterinary Parasite Problems

By W. S. BAILEY, D.V.M., Sc.D.

PARASITISM has exerted a tremendous in-fluence on the livestock industry of the south-

eastern United States. The story of cattletick fever and its eradication is a familiar one.Other parasitic infections of a less spectacularnature have continued to plague our livestock,usually in. the form of inapparent or undiag-nosed chronic infections. Such infections tendto attract little attention until an acute clinicaloultbreak occurs. Certainly parasitism in thedomestic animals is not a problem peculiarto the southeastern States, but a number offactors (1) contribute to make many of ourproblems of greater magnitude than in otherareas of the United States.The very large number of parasites of do-

mestic animals in the southeastern States varygreatly in their distribution, incidence, andpathogenicity. It is difficult to present an ac-curate, brief account of the veterinary parasiteproblems. This is particularly true since ourknowledge of these parasites is, in many in-stances, incomplete or entirely lacking. Thetask is seen to be more difficult when one realizesthat the line of demarcation between clinicaland subelinical, or latent, parasitism is variable,influenced by a number of factors in the host-parasite relationships. Consequently, manyparasites not generally considered to be prima-rily pathogenic may be of importance in a par-ticular disease of an individual or group ofanimals.

Specific parasite problems will be discussedby the host relationship. No attempt will bemade to rank the infections according to im-portance or to catalog all of the parasites thatmay be present as major factors. Rather, abrief summary of internal parasitism in thedifferent animals will be presented, and one ormore entities will be discussed in greater detailbecause of differences in incidence, greater eco-nomic importance, or biological interest.

Cattle

During the past 10 years there has undoubt-edly been a greater change in parasitism ofcattle in the southeast than in any other hostand probably than in any other area. The moststriking aspect of this change has been the com-mon occurrence of clinical parasitism in matureanimals. The figures below illustrate themarked increase in clinical parasitism insouthern Georgia as determined at autopsy byAndrews, Sippel, and Jones at the Tifton, Ga.,ex'periment station (2).

Percent ofcattle with

clinicalYear parasitism

1945-50- -_-- __________________________Negligible1950-51- - ______________--____________ 61951-52_-____________________._____________ 111952-53_____________________--_____________ 17

From March 21, 1952, to June 2, 1953, 14 ani-mals, aged from 6 months to 10 years, werefound to have been suffering from clinical para-sitism at autopsy. The animals were from 10farms on which there was a death loss of 5percent of 1,900 animals.Although the criteria are not exactly the

Public Health Reports

Dr. Bailey is head professor, department of pathol-ogy and parasitology, School of Veterinary Medi-cine, Alabama Polytechnic Institute, Auburn, Ala.

976

same, and, no doubt, evaluators differthese figures appear to be rather clcgiven in the following table takerautopsy records of the department oJand parasitology, School of Veteriicine, Alabama Polytechnic Institut4agnosis for 11.1 percent of 422 cattl4was primary parasitism, and the dian additional 5.6 percent of thesesecondary parasitism.The results of Cooperrider's study

economic losses in cattle due to intsitism further emphasize the comirence and great importance of clisitism of cattle in this area. W(amazed if we could but know the m;the loss resulting from combined csubelinical parasitism of cattle in thThese losses are due primarily t

with the stomach worms, Haemonetagia, and Trichostrongylus. Thesefections are almost always in theparasitic gastroenteritis, with certaiparasites contributing to the diseas4instances the intestinal parasites amary cause of the syndrome.There is relatively little informa

number of these parasites requiredclinical parasitism and death. Thibecause parasitic infections may 1more complex diseases in which nand concurrent or previous infe(

Primary and secondary parasitism 4autopsy at the Alabama PolytechiMay 1, 1953, to Mar. 18, 1955.

Host

Num-berani-malsautop-sied(all

ages)

Primaryparasitism 1

Num-ber

Per-cent

Dog - 532 38 7. 2Cat ------------- 51 3 6. 8Sheep and goat _ 52 8 15.3Cattle _____ 422 47 11. 1Equine-46 3 6. 5Hog - 186 5 2. 6

1 Considered the primary cause of deasidered to be a contributing factor to t]death of the animal.

I somewhat, other pathogens play major roles. Rarely willse to those one find infections witlh more than 10,000from the Hlaernonchus, but as many as 300,000 immature

f pathology Ilaenzonchus have been reported. The presencenary Medi- of 50,000 to 75,000 Ostertagia or Trichostrongy-e. The di- lus, or both, is apparently sufficient to causee autopsied severe symptoms and death in some animals.agnosis for Recent reports include a number of cases withcattle was from 200,000 to 500,000 of these worms, and as

many as 1,100,000 have been found. In theser (3) on the massive infections a large percentage of theernal para- worms often are immature.mon occur- All three of the stomach worms are blood-nical para- suckers and anemia of variable degree is a char-would be acteristic symptom of Haemonchus and Oster-

agnitude of tagia infections. Digestive disturbances, usu-linical and ally in the form of a persistent diarrhea, areLe southeast. almost constantly present. There is a great need) infections for additional information on the host-parasitehus, Oster- relationships of these worms, especially withnatural in- regard to pathogenesis and immunity.form of a The intestinal helminths contributing mostn intestinal to general parasitic gastroenteritis and whiche. In some may be primarily responsible for the diseasere the pri- under certain conditions are: Cooperia spp.;

Bunostomum phlebotornmum, the cattle hook-Ltion on the worm; Nematodirws spp.; and Oesophagosto-to produce mnum radiatumu, the nodular worm.

is is mainly There are a number of other helminths inbe parts of the intestines of cattle, but they generally are ofnalnutrition little pathogenic importance in the southeast.ctions with One or two of these should be mentioned, how-ever. Neoascaris, the cattle ascarid, may be a

as found at problem in individual herds. It apparently isnic Institute, found more in scattered herds in Louisiana and

Florida than in any other of the southeasternStates. The anoplocephaline t a p e w o r m s,

Secondary Moniezia spp., are quite common but appear toparasitism 2 be relatively nonpathogenic. There is, how-

ever, the tendency to attribute damage producedNum- Per- by the minute parasites to these large ones.ber cent Coccidiosis continues to be an important

problem in many herds. Of the 10 species oc-

23 4. 3 curring in cattle in this area, Eimeeria zurnii2 3. 9 and Einteria bovis are the most pathogenic, but1 1. 9 some of the others may contribute to, or be2 5. 3 primarily responsible for, the infection. As is7 3. 7 true with the worm infections, older animals

may also have clinical coccidiosis.hth. 2 Con- Fasciola hepatica infections have been diag-he illness and

nosed in a number of the southeastern States.

Vol. 70, No. 10, October 1955 977

-

At the preseiit tiime tlhe onilv State east of theMlississippi River in whliel Fasciola inifectionis consi(leired to be of any appreciable impor-tance is Flori(la. Fascioloides infection isprobably mnuelh imiore widespread tlhan reportsindicate. Altlhough imany (leer in certain areasof Alabamia, are infected, the first bovine casecami-e to ouir attentioni last vear. It is not knownif the case was an aiitoclhtlhonous infection.

Liungcwornm infection is quiite widespread inthe southeast, aiid is especially important inthe low, wet areas whiclh provide an ideal en-vironment for the larvae. Heavy inifectionsoften result in severe bronclhitis and death. Wedo not appear to have in the area the "atypi-cal" lungworm inifection of mature cattle de-scribed recently by the E-ntglisli workers (4),but the possibility of this shoutld not be over-looked, especially in tlle wet areas.

B3ovine genital trichonmoniasis, caused byTrichtomona.s foetus, lhas been diagnosed inpractically all the States. This disease doesnot appear to have caused as much trouble inmost southeastern States as it lhas in the morelheavily concentrated dairy areas of the mid-wvest. In individual herds in any of the States,lowrever, it may be of g,reat economic impor-tance. Unitil 1954 we knew of no definite diag-nosis of this infection in Alabaina. Our firstdianciosis was made in a lherd into which bredlheifers were brouight from a nmidwestern State.Sinice that time the infection has been diag-nosedl in three additional herds and probablyexists in a nuimber of others.

A.lthough the exact classification of the etio-log,ic acgent of anaplasnmosis is unsettled, it isinclulded witlh the pariasitic diseases in this dis-cussion. In somne of the soutlheastern Statesanaplasmosis is currently of only spotty distri-bution and little importaince. However, SouthCaroliina, Florida, Mississippi, and Louisianamay truly be referred to as enzootic areas. Theinicidence and distribution of this disease is in-tiniiately related to, but not limited by, the den-sity of the several artlhropod vectors which maytransmllit it.

Sheep and Goats

Tlhe lrevalelnce of interin.al parasites was aimajor factor in the (leclinie of the sheep in-

dustry ill a niumber of souitlheasterni States inyears past, and the promiiise of better controlmeasures has contribuited to an increase in thesheep l)opulation in recenit years. Since manyof the problems are mulch the saime as for cattleaind are produced by the same or closely relatedspecies of parasites, nio separate discussioni forthese hosts will be given in this genieral ancdbrief review.

Swine

A number of the gastroiiitestinal parasites ofhogs are not appreciablv different in the south-eastern States from most of the rest of the coun-try, although the intenisity of infection may besomewhat heavier. The stomach worms arewidely distributed, but are not often primarilyresponsible for trouble. The hog ascarid is alsowidely distributed andl of major importance.Undoubtedly many of the factors relating to thedistribution and epidemiology of the humanascarid are also operative in this infection.The thorny head worm of hogs is not as

widely distributed as the ascarid but may bean important problem in given herds, in whichcontrol is difficult. Occasionally, deatlh occursfrom light infections due to peritonitis result-ing from perforation of the intestinal wall bythe proboscis. Of the several species of nodu-lar worms infecting the lhog, only one, Oesopha-qostomum dentaturn, appears to be widely dis-tributed in this country. The others are some-what restricted to the southeastern States.L-ungworm infecti-on is quite common and isoften the cause of respiratory symptoms andeven death.The kidney worm of hog,s, Stephanurus

dentatus, is of little importance outside thesoutheast. In fact it is only in the lower tierof States and up the Atlantic seaboard to Vir-ginia that the infection is of any great signifi-cance. In these areas, lhowever, it is still a ma-jor problem, and losses occur in a number ofways. The loss most easily determined is thatclue to condemnationi or trimming of parts ofcarcasses at the killing abattoir.

Accordingr to a personal communication fromJ. A. Lang,ford a heavy inifection with the lar-val stage of Diphyllobothriumn (Spirornetra)

Public Health Reports978

?Aalonoiides was diagnosed in a ranige lhog inFlorida recently.

Poultry

Little will be said about poultry parasites.Tflie common gastrointestinal lielninths andprotozoa are widely distributed and of variableimi-portance througlhout the southeast.Leucocytozoon 8mithi infection of turkeys ap-

peals to be quite coinmon in many parts of thesoutheast, as evidcenced by tlhe observations ofa number of workers (5-8). Bierer (8) indi-cates that this is primarily a disease of the tide-water area along the eastern seaboard. Receintoutbreaks in Soulth Caroliina lhave been par-ticularly striking. Wild turkeys apparentlyserved as a reservoir of infection. The diseasemay be very acute and highly fatal as describedby Stoddard and associates (7), who reported75 percent mortality of 1,600 birds in 7 days,or it may be more insidious and with low mor-tality. The latter outbreaks may be associatedwith the breeding season in wllich case thereseems to be a greater mortality in toms thanin liens.

Equines

W'ith the decrease in the lhorse and mule pop-ulationi, a niumber of the parasite problenms inthese aninmals have becoiie less marked but havebv no mlealns disappeared. Bot infections arestill very common, and marked gastritis due toinfections with Triehostrongylwu axei is quitecommon. The latter is not surprising, in viewof the increasing importance of this parasite inrUiinants, inasmuch as there is good evidencethat cross transmission occurs. Cutaneousliabronemiasis is seen much less than in earlieryears. However, this disease may constitute aproblem on even the best of farms if the animalsaire infected with the adult worms and there isa hiigh transmission potential because of aInabundant fly population.The most important intestinal parasites are

the asearid, Parascaris equoruru, and the stron-fgyles, particularly the larrge strongyles, Stron-!f?/lms q'mdg as AStronflybiq edentatus, andSt)Oyl uyms equinus. Asearid inifections areusually of clinical signiiificance onily in young

anim11als. In additioil to the bloodsucking ac-tivitv of tile large strongyles, the parasiticanemNrsin produced by S. vulgaiis is of greatimportanice. This anieurysm, witlh the resultingtllrombus forimiation, of the anterior mesenteiricartery may cause a variety of intestinal dis-turbances, and frequently results in death. Pin-wormii infection may constitute a problem in in-dividual or groups of aiiimals, but it generallyis of little pathogenic importance.

Dogs and Cats

Spirocerca lupi, the dog esophageal worm, ap-pears to be very rare in this country except inthe south. Over a period of approximately4 years we have found slightly over 4 percentof 943 dogs of all ages infected (9). Since thisincludes a large number of puppies, the in-cidence in dogs old enough for the life cycleto have been completed would be appreciablyhiigher. Only a small percentage of the dogsinfected with Spirocercca show clinical symp-toms. However, this infection takes on addedinterest and importance in view of the recentreport by Seibold and associates (ZO) that itmay be an inciting cause of the development ofnmalignant esophageal tumors of the dog.A number of intestinal helminths are very

widely distributed, not only in the southeast buitin much of the Nation, and some are highlypathogenic. We have no comprehensive figureson the incidence of Strongyloides in the dog inthe soutlheast, but it is certainly nmore commontlhan the reports indicate. It is often the causeof respiratory symptoms and intestinal disturb-alice, and the mortality rate in heavily infectedpuppies is quite high. Altlhough the worm isapparently indistinguishable from Strowgy-boides of inan, it is likely that man does noteasily become infected with the dog form.The hookworms, Ancylostonta caninum and

Ancybostoma braziliense, continuie to take a

heavy toll of our young dogs. Prenatal in-fectionis are very common and highly patho-g,enic. Some of the heaviest infections havebeen in miature dogs concurrently suffering withsome other disease.Roundworm infections are very common, es-

peciallv in vouiiig dog s, with prenatal infection

Vol. 70, No. 10, October 1955 979

again being of great importance. Toxocaracanis is the one most often encountered.Light tapeworm infections are found in a

high percentage of dogs, and heavy infectionsare common. Dipylidiurn caninum is the onefound most often in this area, but Taenia taenia-formis and Taenia pisiformis are not uncom-mon and seem to occur most often in the cat.There is a recent report of natural infection ofdogs with Echinococcus granulosus in Missis-sippi (11). The public health importance ofthis needs no elaboration.

Pseudophyllidean tapeworms appear to berare in dogs in this area. Diphyllobothriumlatum has been reported from Florida. D.(ASpirometra) manmonoides has been reportedfrom Louisiana and, during the past year, fromthe Alabama-Georgia area (12). Langford,who recently sent us the larvae of this parasitefrom a hog, in his letter reported finding a num-ber of cases of Diphyllobothriwim infection indogs and cats.Light to moderate infections with the whip-

worm, Trichuris vulpis, are common in the dog,and occasionally very heavy infections are en-countered in which the parasite is apparentlythe cause of death. In such cases not only isthe cecum filled with worms, but the entire sur-face of the colon is covered.A number of intestinal protozoa are com-

monly found in the dog. Eyles and associates(13) have recently reported finding 8.4 percentof 143 dogs in Memphis, Tenn., infected withEntamoeba histolytica, using cultural methods.We certainly agree with their observation thatcysts of E. histolytica are almost never passedand that the trophozoites are passed in smallnumbers in the feces of dogs.Shown below are the protozoan infections

found by direct smear examinations at the smallanimal clinic, Alabama Polytechnic Institute,from September 1953 to May 1954. Of 871 dogsexamined, 193, or 22 percent, were found to haveprotozoan infections, although there may havebeen more than one infection per dog.

GiardiaTrichomonasIsosporaEntamoeba histolyticaEntamoeba coliBalantidium__

Number755744719

Percentt&6

6. 55. 0

. 8

. 11. 0

Each of the seven dogs infected with E.histolytica showed a characteristic profusediarrhea, continuous or intermittent and oftenof long duration. In the E. coli infection, cystswere being passed, and this dog was concur-rently infected with E. histolytica. Only asmall percentage of the dogs infected withGiardia showed symptoms attributable to theorganism. It is possible even in these cases thatthe symptoms are not due solely to the proto-zoan. There is evidence (14) suggesting thata combined Giardia (protozoa) and Pseudo-monas (bacteria) infection may be quite patho-genic in the chinchilla. The intestinaltrichomonads are common in the dog, and theincidence figure rises rather markedly whencultural methods are used in diagnosis. Hereagain the organism appears to be associatedoccasionally, apparently in some causal rela-tionship, with a severe diarrhea, which may alsobe of long duration.Even though occurring in a low percentage

of dogs, Balantidium infection is much morecommon than we had earlier suspected. Itappears to be pathogenic in the dog in prac-tically every infection. Light infections withthe dog coccidia are common, and when ani-mals, especially puppies, acquire heavy infec-tions, marked symptoms and death may result.In Georgia, 2 of 3 recently reported cases ofhuman infection with Isospora appeared to berelated to an infection in the family dog (15).Although we probably have more information

on the distribution of Dirofilaia im/miti8, thedog heartworm, than on almost any other ofthe parasites of veterinary importance in thesoutheast, its distribution still has not been welldefined. The infection is obviously quite com-mon in many areas where it is not present atdisease-producing levels. The presence of adultworms in sufficient numbers to result in clinicalinfection is evidence of a high transmission po-tential. On the basis of current informationthis appears to be common in the southeast onlyalong the seacoast. There are inland areaswhere the transmission potential is sufficientlyhigh to result in the presence of moderate num-bers of adults and even in some instances inclinical infection, as emphasized by Eyles andassociates (16) in their recent study in the areaof Memphis, Tenn. Auburn, Ala., is a good

Public Health Reports980

example of an area with low transmission po-tential. In a recent limited survey it was foundthat microfilariae could be demonstrated, usingconcentration procedures, in approximately37 percent of the dogs. Our autopsy recordsof the past 5 years have not been summarizedto give the incidence of adult worms, but itcertainly is appreciably lower than the 4 per-cent found in Memphis. The only clinical caseswhich have come to autopsy in recent yearswere sent to us from coastal areas where theinfection is certainly a major problem.There are a few reported cases of the giant

kidney worm, Dioctophyma renale, in the south-eastern States (17). There appears to be asmall enzootic area in southeast Georgia.We do not know how common canine toxo-

plasmosis is in the southeast. Serologic testsmade elsewhere indicate that inapparent orotherwise undiagnosed cases are quite common,as in other animals. From July 1954 throughMarch 1955 we autopsied 148 dogs, of which 6,4 percent, were diagnosed as toxoplasmosis, ortoxoplasmosis together with distemper. In ad-dition to these cases from autopsy, all of whichwere from Alabama, we have made a diagnosisduring this period of toxoplasmosis from atleast one place in Florida, Georgia, South Caro-lina, Virginia, and Tennessee by the histologicalexamination of tissues sent to us by practicingveterinarians.The cat lungworm Aeleurostrongylus ab-

strusus, has been reported from Maryland, Vir-ginia, North and South Carolina, Georgia,Tennessee, and Alabama (18). In these Statesalthough there are few reports of the infection,mostly only 1 or 2, many of these are fatal in-fections. Probably the infection is much morecommon than published reports indicate, as sug-gested by the recent finding of the infection in6 of 50 cats in a Virginia county.

Information Needed

There are many different aspects of these andother infections that could profitably be dis-cussed. This very incomplete account will beclosed by pointing out the general needs withregard to veterinary parasitology in the south-east.

1. More information on the distribution and

incidence of parasitic infections to determinemore clearly the true nature and extent of theproblem.

2. Better use of the information currentlyavailable in the control of these parasites.

3. More information on the biology and host-parasite relationships of the many parasitescommon in the southeast, for only on this foun-dation can we build truly effective controlprograms.

REFERENCES

(1) Schwartz, B.: Parasitism in relation to the live-stock industry of the south. Scient. Monthly,54: 448-454, May 1942.

(2) Andrews, J. S., Sippel, W. L., and Jones, D. G.:Clinical parasitism of cattle in the southeast.Proc. U. S. Livestock Sanit. A.: 228-238 (1954).

(8) Cooperrider, D. E.: Losses in cattle due to in-ternal parasitism. North Am. Vet. 35: 350-353,May 1954.

(4) Taylor, E. L.: Parasitic bronchitis in cattle.Vet. Rec. 63: 859-867, Dec. 22, 1951.

(5) Travis, B. V., Goodwin, M. H., Jr., and Gambrell,B.: Preliminary note on the occurrence ofLeucocytozoon smithi Laveran and Lucet (1905)in turkeys in the southeastern United States.J. Parasitol. 25: 278, June 1939.

(6) West, J. L., and Starr, L. E.: Further observa-tions on a blood protozoan infection in turkeys.Vet. Med. 35: 649-653, November 1940.

(7) Stoddard, E. D., Tumlin, J. T., and Cooperrider,D. E.: Recent outbreaks of Leucocytozoon in-fection in adult turkeys in Georgia. J. Am.Vet. M. A. 121: 190-191, September 1952.

(8) Bierer, B. W.: Buffalo gnats and Leucocytozooninfection of poultry. Vet. Med. 49: 107-110,March 1954.

(9) Folse, D. S., and Newberne, J. W.: Spirocercalupi infection in dogs. A four year survey.North Am. Vet. 35: 519-522, July 1954.

(10) Seibold, H. R., Bailey, W. S., Hoerlein, B. F.,Jordan, E. M., and Schwabe, C. W.: Observa-tions on the possible relation of malignantesophageal tumors and Spirocerca lupi lesionsin the dog. Am. J. Vet. Res. 16: 5-14, January1955.

(11) Franklin, M. A., and Ward, J. W.: Echinococcusinfections in Mississippi. A new record of anatural infection in dogs. J. Parasitol. 39:574, October 1953.

(12) Thorson, R. E., and Jordan, U. M.: A pseudo-phyllidean tapeworm from a dog in the south-eastern United States. Proc. Helminthol. Soc.Washington 21: 123-124, July 1954.

Vol. 70, No. 10, October 1955 981

(1,3) Eyles, D. E., Jones, F. E., Jumper, J. R., andDrinnon, V. P.: Amebic infections in dogs. J.Parasitol. 40: 16.3-166, April 1954.

(14) Shelton, G. WV.: Giardiasis in the chinchilla. II.Incidence of the disease and results of experi-mental infections. Aiii. J. Vet. Res. 15: 75-78,January 1954.

1la) Itouth, C. P., McCroan, J. E., and Hamer, C. G.:Three cases of human infection with Isosporain Georgia. AIm1. J. Trop. Med. & Hyg. 4: 1-8,January 1955.

(16) Eyles, D. E., Gibson, C. L., Jones, F. E., andCunningham, M. E. G.: Prevalence of Dirofilariaim mnti8 in Memphis, Tennessee. J. Parasitol.40: 216-221, April 1954.

(17) Ehrenford, F. A., and Snodgrass, T. B.: Incidenceof canine dictophymiasis (giant kidney worminfection) with a summary of cases in NorthAmerica. J. Am. Vet. M. A. 126: 415-417,May 1955.

(18) Bailey, W. S., and Lowman, C. B.: Verminouspneumonia. Auburn Vet. 9: 36-38, Fall 1952.

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