Phne: (08) 8999 2249 Fax: (08) 8999 2024 Email: ahnnt@nt.gov.au Website: www.dbird.nt.gov.au ISSN: 1446-5094

ELSEY VIRUS – AN ISOLATE OF PERUVIAN HORSE SICKNESS VIRUS?

In 1999 identical viruses were isolated by staff of the virology laboratory at Berrimah Veterinary Laboratories (BVL), from each of two horses in the Katherine region. The horses were euthanased while suffering severe neurological signs. The first isolate was named “Elsey” virus after the station where one affected horse resided. Following extensive serological testing and subsequent morphological examination by electron microscopy, Elsey virus was determined to be a member of the orbivirus group, not a recognised member of any Australian orbivirus serogroup, and apparently novel. The virus was subsequently sent to the Australian Animal Health Laboratory (AAHL) for further testing to viruses not available at the BVL. The findings from BVL were confirmed at AAHL. AAHL also tested the virus against a range of exotic viruses and confirmed it was not a recognised pathogen. The only virus that showed any serological similarity to Elsey virus was another unknown orbivirus isolated at BVL from sentinel cattle located at Beatrice Hill Farm, 300km north of the Katherine region. An application for funding to further investigate Elsey virus was made to the Wildlife Exotic Disease Preparedness Program (WEDPP). Funding was received to carry out sero-surveys in the NT and for AAHL to sequence the virus to aid in identification. A serological survey of stored equine sera collected between 1993 and 2000 was conducted. Four hundred and eleven sera were screened at 1:5 dilution in a neutralisation test using Elsey virus. Forty sera were positive with the highest titre of 40 being detected in case one. Seropositive horses were detected at 12 locations within the recognised arbovirus endemic area of the NT. Seroconversions were demonstrated in three animals where repeat bleeds had been submitted for an undiagnosed syndrome of mild colic and behavioural change. During 2001 a further 107 horses were tested for antibodies to Elsey virus with 13 positive and in 2002-2003, 71 were tested with 14 positive. A retrospective survey of stored sera found antibody in the Katherine region as early as 1981-82. Species other than horses were also tested for antibody to Elsey virus. The most surprising results came from bat sera (black f lying foxes and red flying foxes). In a sample of 78 bat sera 36 were positive with higher titres than those seen in horses. A small number of macropods (11 out of 253 tested) were also positive. No detectable antibody was found in 102 rat sera. A very low prevalence of antibody was found in cattle and pigs. AAHL recently completed sequencing of gene segment 9 of Elsey virus. This sequence was compared to a large number of orbivirus sequences that have recently become available through a project involving the Institute of Animal Health at Pirbright, United Kingdom. Elsey virus and a newly described orbivirus from Peru were found to have almost identical gene segment 9 sequences. The Peruvian virus was associated with an outbreak of meningoencephalitis in Peru in 1997 that caused the deaths of 100 horses. The virus isolated from this outbreak was called Peruvian Horse Sickness Virus (PHSV). Further testing of gene segments 10, 2 and 3 has shown these are also almost identical (>99% homology) with PHSV.

Lorna Melville VeterinaryVirologist

8999 2251 Editor’s Note: Articles on the research for this virus appear in AHNNT Issue 18, July 2000, Issue 21, July 2001 and Issue 30, July 2003.

Inside Issue 35; October 2004

Person in Profile Page 2

Clinical Pathology of Farmed Crocodiles Page 3

New Parasites in Australia Page 4

CVO’s Report Page 4

Parasite Control in Sheep Page 5

Out and About Page 5

New Test for Giardia Page 6

AHNNT - Issue 35; October 2004 Page 2

Two years ago I gained the opportunity to work at the Berrimah Veterinary Laboratory (BVL) in the specimen reception section. Although I had a long association with the pastoral industry I faced a steep learning curve with all the terminology of diagnostic samples and the variety of tests performed at the lab. I have found this to be a most rewarding and interesting experience. Prior to coming to the vet lab I had been working at the Berrimah Research Farm for two years as a ‘floating’ personal assistant relieving when other staff were on leave. This was an opportunity to gain a great background into the various roles of each section at the farm having worked in Fisheries, Resource Management, Resource Protection, Publications, Executive, Horticulture, Records and two weeks relieving in the Tennant Creek office. Before I joined primary industries I worked for Parks & Wildlife for eight years a t the Territory Wildlife Park as both a park g u i d e a n d z o o k e e p e r , s p e c i f i c a l l y working in the raptor section for two years. Many h o u r s d o i n g voluntary work lead to a position working full time with the raptors and doing twice daily displays for the public. Working with raptors was both challenging and rewarding and there were often some ‘hair raising’ moments particularly with the large eagles. If they did not accept you, you had to be on your toes with handling them as they were deadly quick with those talons. (I have the scars to prove it). I found the wedge tailed eagles to be a joy and the sea eagles the most temperamental. We handled a variety of birds from a delightful barking owl, brahminy kite, osprey, black breasted buzzard and black kites. This reminds me of one embarrassing moment which arose when doing a raptor display at the TWP in front of an audience of 300 people including management and I am first presenter out with the sea eagle and cast her off to her high perch. I then realized we had left a plastic fishing reel out on the oval from training with a previous bird. She then attacked it, took it up to the perch and refused to move. Of course with an eagle on the loose we were not

able to fly another bird (usually flew three) and we had to make a riveting and interesting display for the audience with showing two smaller birds on the fist. It was late afternoon when we were finally able to coax the eagle back to the glove. I still have a strong interest in raptors today. While working at the TWP I also became keenly interested in the native flora, and learnt a great deal about the local species, documented several plant walks at the wildlife park and conducted many ‘bush tucker walks’, I was also given the opportunity to do temporary work at the Darwin Herbarium which was another role that I loved. In the 80’s I was involved in the pastoral industry,

in particular with cattle and buffalo mustering and the BTEC program. I spent many years living in mustering camps, was involved with the culling of buffalo at Kakadu in the early 80’s and a s s o c i a t e d w i t h Peppimenarti for some six years and still have t i e s w i t h t h i s community. Many l o n g s t a n d i n g f r iendships have remained from these e x c i t i n g a n d challenging times. I remember assisting Jenny Purdie with s e v e r a l i n s e c t

collections and also collecting dung beetles. Although my early training years ago was secretarial (I was legal secretary for three years doing shorthand every day) I felt the need to keep up with the times and become computer literate and took myself back to University as a mature age student and completed a Certificate in Business as I felt that eight years of working out in the sun and weekends at the Wildlife Park it was time for a change. I enjoy my work at the vet lab, no two days are the same, it is always busy and extremely interesting with a great variety of work and I have been fortunate to work with a great group of people and still maintain ties with the pastoral industry. For many years I have been involved and owned quarter horses and have been a member of the NT Quarter Horse Assoc. since it’s conception. I still do the occasional horse show and have a wonderful aged gelding. In 1984 I won the High Point

(Continued on page 3)

Person in Profile- Meg Gayoso

AHNNT - Issue 35; October 2004 Page 3

To assess the merit of pursuing haematology and serum biochemistry as part of disease investigations in saltwater crocodiles (Crocodylus porosus), post-mortem and clinical pathology records of juvenile crocodiles (one to six months old) with bacterial septicaemia were evaluated (34 cases total, N=16 for haematology, N=25 for biochemistry). Bacterial isolates in 80% of cases were gram negative, with Providencia rettgeri, Pseudomonas and Salmonella spp. predominating. Many affected crocodiles also had fungal dermatitis. Gross pathological findings in septicaemic one to six month old crocodiles may be limited to mild oedema surrounding abdominal and thoracic viscera, or there may be more obvious changes of severe subcutaneous oedema and cellulitis, including swelling of entire limbs, or fibrinous exudates on serosal surfaces such as the epicardium. Histopathological findings may include multifocal splenic or hepatic necrosis, with or without heterophil infiltration, fibrinous epicarditis, heterophilic cellulitis or meningitis, often with intralesional bacteria visible. The haematology parameters in the septicaemic juveniles were evaluated against normal reference values for crocodiles, six weeks of age from an NT research facility (N=140, Turton et al 1997). Septicaemic crocodiles had higher mean total WBC count (21.0x109/L) than normal crocodiles (5.3x109/L). This difference was not significant due to wide variation (SE=7.2) in septicaemic crocodiles. Similar findings were evident for mean heterophil counts (5.7x109/L in septicaemic vs 3.1x109/L in normal) and lymphocyte counts (12.3x109/L in septicaemic vs 1.7x109/L in normal). Evaluation of biochemical parameters proved more problematic, in that normal values for very young

saltwater crocodiles were not available. The closest comparison group was saltwater crocodiles , one to two years of age from four NT farms (N=30 from each farm, Millan et al, 1997). Analysis of mean biochemical parameters between this group and the septicaemic younger crocodiles revealed significantly higher CK, AST and uric acid in septicaemic crocodiles, lower albumin, glucose, Na and Cl in septicaemic crocodiles and no significant differences in ALP, TP, globulin, K, Ca or P. However, the validity of comparing biochemical parameters between crocodile groups that differ with respect to age, environment or husbandry practices is questionable. For example, further evaluation of data from normal one to two year old crocodiles revealed significant differences between the four farms for 15 out of 19 serum biochemical parameters measured. Saltwater crocodile farms in the NT are roughly similar with respect to husbandry, environment and diet, indicating that minor alterations in these factors may significantly influence serum biochemistry.

Cathy Shilton, Veterinary Pathologist,

8999 2227 Greg Brown, University of Sydney reptile biologist

References Millan JM, Janmaat J, Richardson KC, Chambers LK, Fomiatti KR. Reference ranges for biochemical and haematological values in farmed saltwater crocodile (Crocodylus porosus) yearlings. Aust Vet J 1997;75:814-817. Turton JA, Ladds PW, Manolis SC, Webb GJW. Relationship of blood cortisone, immunoglobulin and haematological values in young crocodiles (Crocodylus porosus) to water temperature, clutch of origin and body weight. Aust Vet J 1997;75:114-119.

Clinical pathology of septicaemic farmed crocodiles in the N.T.

(Continued from page 2) Senior (over 18) Award for the season. My other hobbies and interests include reading, photography, travel, line dancing, swimming, music & gardening. I was asked the question ‘What one person in the world do you admire the most and why?’ Well I have two!. Bronwyn Bishop (I listened to her as a guest speaker some years ago) and she spoke for 40 minutes without any notes and also remembered my name and the name of the bird I was flying from watching a raptor display some time earlier. Also Madeleine Albright the former US Secretary of State – both dynamic women.

AHNNT - Issue 35; October 2004 Page 4

Snippet from conference of the Australian Society for Parasitology, October 2004. With the increased movement of pets around the world, we need to expect the introduction of new parasites. Last year there were 53 200 dogs brought into the United Kingdom, with subsequent introduction of new diseases - eight cases of Leishmania, six cases of Babesia and five cases of Ehrlichia. At the same time, 5342 pets, 3222 of which were dogs, arrived in Australia and bought with them ticks, Leishmania and Babesia canis rossi. Dr Peter Irwin, from Murdoch University, presented data on three previously considered exotic, vector borne, parasitic diseases of dogs that have been discovered in Australia since 2000. • Anaplasma platys (previously called Ehrlichia) has been detected in dogs in central Australia. These dogs present

with mild bleeding and have a cyclic thrombocytopaenia. Despite extensive research in northern Australia using molecular techniques, the more virulent species of Ehrlichia, E. canis, has not been detected in dogs.

• Babesia gibsoni , a more pathogenic species than our endemic B. canis vogeli, was initially detected in two American pit bull terriers in Victoria. There are now nine cases. This disease is prolific in SE Asia. It is mainly associated with fighting dogs, and of interest, is the idea that there is direct transmission of the parasite, without an intermediate host such as the brown dog tick.

• Leishmania infantum was detected in a dog in Western Australia , three years after its importation from Portugal. This is an increasing problem in foxhounds in the USA. Again, there is a suggestion that transmission may not require vectors such as the sand fly.

Lois Small Parasitologist

89992245

Avian Influenza Clinical cases of avian influenza in poultry and humans have again been reported in Indonesia, Vietnam and Thailand in recent weeks. I request all veterinarians to consider avian influenza in investigation of deaths in poultry and other birds. An emergency animal disease exercise involving a number of infected and non-infected States will be carried out during late 2005. The exercise will involve industry, agricultural agencies, health, and food agencies. If there was an avian influenza outbreak in the major meat chicken growing areas of Australia there would be major shortfall in the supply of chicken meat to Australian consumers, therefore supply of chicken meat for domestic consumption would be an issue. Poultry enterprises would be depopulated as part of the response. Consumers would be on a chicken drought!. Bovine Tuberculosis Tuberculosis has not been found during surveillance in cattle and buffalo carried out by TB testing in the field and autopsies in herds without abattoir monitoring. The last TB case in cattle was in 1998 and in buffalo in 2002. The Tuberculosis Freedom Assurance Program 2 is operating from 2003 to 2006. The program involves the removal of any cattle previously exposed to infected animals despite testing history and ongoing surveillance. A mid term review will be conducted during the last half of 2004. Live Exports Following the Cormo Express issue during 2003 with sheep excluded from importation to Saudi Arabia due to alleged, but not substantiated disease concerns, and a number of incidents during the export of cattle and sheep

during 2002 and 2003, Minister Truss initiated a report on the export of cattle and sheep (Keniry report). Most of the recommendations were accepted by the Australian Government, with more direct involvement by government to register and audit exporters and approved veterinarians, approve a code for the export of livestock and standards to be used under the Export Control Act. Independent final inspection will be done prior to loading on ships. I am a member of the Live Exports Standards Advisory Committee, which has been formed to advise the federal minister of a code and standards for the export of livestock from Australia. Membership includes producers, exporters, RSPCA, shipping operators and regulators and representatives of the commonwealth and state jurisdictions. The new standards will be operational from 1 December 2004. I expect that there will be revision during 2005 as experience with the use of the standards is acquired. There is very good performance of the export process of feeder cattle from Darwin to South East Asia with a mortality of four per 10,000 exported. Despite major improvements during the last few years, the major national issue in the livestock export industry is the export of sheep to the middle east. While there is always potential for continuing improvement, there will be minimal changes needed for the export cattle industry from northern Australia.

Brian Radunz Chief Veterinary Officer

8999 2130

AHNNT - Issue 35; October 2004 Page 5

Crisis looming for parasite control in sheep in Australia How do we treat animals for worms? We drench them of course! And drench them, and drench them, and drench them, and now suddenly there are no drenches left that will kill worms in sheep. (Or almost.) We use chemicals because they are simple and convenient to use, work immediately, are broad acting, are often cheap, and basically everyone can use them. Despite problems with ecotoxicity and residues, chemicals are still used continually. Worm control is currently based on treatments with broad spectrum anthelmintics such as benzimidazoles (BZ), levamisole (Lev) and macrocyclic lactones (ML) and narrow spectrum anthelmintics such as closantel for Haemonchus. The prevalence of drench resistance on farms in WA, Vic and NSW of 90-95 % for BZ and 80-90% for Lev has been reported. Efficacy for these treatments has fallen to 60% in Western Australia. A survey in NSW found closantel resistant Haemonchus in 60% of flocks. Resistance to ML has been reported on 30-40% of farms in WA and NSW. For many farmers this is the last drench group that is still effective, but resistance is increasing rapidly. The common thinking throughout Australia and the rest of the world is that now that there is multiple drug resistance, there is a need to apply alternate strategies to the use of chemicals or to use the chemicals in different ways. A novel idea that is receiving attention is a turn-around in current drenching dogma, of treating all animals in a herd. Instead only the needy are treated, based on an index such as weight or degree of anaemia. In this way resistant worms will be diluted with susceptible worms on pastures and the effective life of the drench will be extended.

Although there are only a few sheep in the NT, we do have goats, which carry the same parasites as sheep and suffer the same chemical resistance problems. Anthelmintic products form the basis of helminth control practices for goats. Annual monitoring for anthelmintic resistance is an essential component of prevention programs given the high prevalence of resistance.

Lois Small Parasitologist

8999 2245

Lorna Melville and Neville Hunt attended the Arbovirus Research in Australia Symposium, 24th-27th August, in Noosa, Queensland. They reported that several well-received presentations were given, and the excellent quality of the powerpoint presentations put together by the virology section was complimented. Presentations included results of virology section research on: vector capacity of Culicoides spp. from Timor, bluetongue persistence in sheep and cattle skin, chemical trial for decreasing vectors in pens, a decade of arbovirus monitoring, bluetongue antibody persistence in Alice Springs, macropod arboviruses and associated diseases over the last four years and horse viruses, including the recent Elsey/Florina sequencing information. Cathy Shilton, as the NT coordinator for the Australian Wildlife Health Network, participated in an Australian Government workshop on wildlife disease surveillance in Australia, in Canberra , September 22nd -23rd 2004. The Australian Society of Veterinary Pathology Conference in Brisbane was attended by Cathy Shilton from October 15th -17th. Themes for the conference were emergency and exotic diseases and clinical pathology. Cathy presented information on clinical pathology of farmed crocodiles (see article page 2).

Lois Small attended the Australian Society for Parasitology Annual Conference in Perth, in late September 2004. See AHNNT article page 4. Peter Saville, Regional Veterinary Officer, Alice Springs, attended the Exotic Disease Training Course at AAHL between September 6th - 13th 2004. They were working with Highly Pathogenic Avian Influenza at the time this picture was taken.

Peter is standing centre back line.

Out and About with Animal Health Staff

AHNNT - Issue 35; October 2004 Page 6

Articles on topics of interest and letters to the editors are invited.

Please mail contributions to: AHNNT

Berrimah Veterinary Laboratories DBIRD

GPO Box 3000 Darwin NT 0801

Or fax to:08 8999 2024

Or e-mail to:ahnnt@nt.gov.au

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The Northern Territory of Australia and the Department of Business, Industry and Resource Development disclaim any liability or responsibility or duty of care towards any person for loss or damage (including special, indirect or consequential loss or damage such as loss of revenue) suffered or caused by any use or reliance on this information. The information is provided without express or implied warranty. While care has been taken in the production of this newsletter, it is provided as general information only and the Northern Territory of Australia and the Department of Business, Industry and Resource Development do not assert that it is complete, accurate or current. The Northern Territory of Australia and the Department of Business, Industry and Resource Development accept no liability or responsibility (including for negligence) if it is misleading or incomplete or if it contains errors, omissions or is inaccurate in any way. No person should rely on this newsletter for the purpose of taking any course of action including any serious, business or investment decisions without obtaining independent and/or professional advice in relation to their particular situation.

BOTULISM IN CATTLE On a station near Katherine a total of 58 of 1400 heifers died over a period of one month. The remaining sick animals were yarded and the healthy cattle moved to another paddock. No supplements were available, and old carcasses were in the paddock. Affected cattle had ascending paralysis of varying degrees of severity, ranging from slight hind leg ataxia to being downers. Post mortem examination of two heifers showed no pathology. The owner reported that not all of the group had been vaccinated against botulism and that no boosters had been administered. Blood samples were taken from 45 cattle to determine their antibody status, and 20 were not protected.

IRONWOOD POISONING IN GOATS Ironwood toxicity was the likely cause of the sudden death of 18 of 100 goats placed in a small riverside paddock on a Katherine property. Post mortem revealed extensive cardiac haemorrhage and hyperaemic small intestines. Surviving goats showed sunken, pale staring eyes and abdominal pain. Ironwood leaves, Erythrophleum chlorostachyum, are highly toxic when ingested. The toxic ingredient is erythrophleine.

A new test for Giardia is being offered

by the Berrimah Veterinary Laboratories.

Present methods for the detection of Giardia cysts in faeces are based on faecal flotation or sedimentation tests. As the cysts are excreted intermittently, diagnosis based on presence of cysts is difficult. The new test is called the Giardia Microplate Assay and uses monoclonal antibody for the detection of Giardia Specific Antigen in faecal specimens. Giardia Specific Antigen (GSA 65) is a macromolecule that has been found in association with Giardia infections and has been used as the basis of immunoassays. GSA 65 is glycoprotein that is produced in abundant quantities by the Giardia protozoa as they multiply within the host intestinal tract. The antigen is present only when Giardia infection is present and it is possible to find in faecal specimens without visible signs of cysts or trophozoites. The sensitivity and specificity of the test with human samples is over 96%. Cost for the new test will be $50 for individual faecal samples. For further details contact the Berrimah Veterinary Laboratories on 8999 2249.