It has been some time since our last newsletter — a reflection of the significant effort and focus required over recent months to respond to high pathogenicity avian influenza (HPAI). This work has included ongoing preparedness for a potential H5N1 incursion, and response to an outbreak of H7N8 in commercial poultry in Euroa which was detected in early February.

The Euroa outbreak once again highlighted the vital role of early detection and reporting by private veterinarians and the importance of strong biosecurity in minimising impacts to industry. A reminder to call the EAD hotline to make reports, 1800 675 888.

Thanks to strong collaboration between industry and government, the outbreak was swiftly brought under control with 13 June marking the completion of all property resolution and surveillance activities, allowing control area restrictions to be lifted.

The response saw more than 100 people working on the ground each day, conducting 360 property visits and 977 separate laboratory submissions for testing. Private veterinarians were central to the effort, contributing across field surveillance, epidemiology, laboratory support, public communications, decontamination, and valuation.

In the past 18 months, private veterinarians have been central not only in responding to HPAI incidents but also to a range of other incidents, including the 2024 anthrax response, Grampians fires, and other emergency animal disease responses. Thank you to everyone that contributed either directly in the field, or indirectly to these efforts.

Beyond emergency animal disease response, the ongoing drought conditions across much of Victoria have continued to place pressure on farmers and veterinarians, with feed shortages, animal welfare concerns, and production impacts front of mind.

While recent soaking rains have brought welcome relief, dams refilling and paddocks greening, the drought is far from over, and its impacts will be with us for some time. Drought support information, online tools and calculators are available on the Agriculture Victoria website.

In recent months, I was also fortunate enough to be part of the Australian veterinary delegation, at the 92nd WOAH General Session held in Paris in May.

A highlight was participating in a panel on Incident Management Systems, as well as contributing to this year’s Animal Health Forum on Veterinary vaccines and vaccination: from science to action — reflections for change.

Australia played an active role in a writing group that drafted a resolution on this topic, which was subsequently adopted by WOAH and its members. It was also an opportunity to hear about the Foot and mouth outbreaks in Europe where early detection was crucial to preventing onward spread. 

Figure 1: The Australian Delegation to the WOAH 92nd General Session (supplied AVA)

Locally, preparedness for H5N1 remains a high priority. While Australia remains free of H5N1, its unprecedented impacts and spread internationally, highlight the continual need to remain vigilant. Preparedness is never finished, but together we’re always moving it forward.

In this edition, you’ll find:

• a summary of the H7N8 response in Euroa
• the wrap-up of Japanese encephalitis virus (JEV) surveillance for the 2024–25 season
• an incident report where drought-driven grazing changes led to a case of plant toxicity
• a rare case of lissencephaly identified in the investigation of ‘shaker’ piglets
• recent study findings about the impact of Neopsora caninum in Victorian dairy farms
• an update on Buruli ulcer
• Victoria’s annual animal health surveillance report.

I trust you will enjoy reading it!

Dr Graeme Cooke
Chief Veterinary Officer (CVO) Victoria

On 8 February 2025, Agriculture Victoria confirmed an outbreak of high pathogenicity avian influenza (HPAI) H7N8 at a free-range egg farm near Euroa. Laboratory testing confirmed the HPAI H7N8 virus was genetically related to strains detected in wild birds in Australia, but different from the strains detected and eradicated in Victoria, New South Wales and the Australian Capital Territory in 2024. The strain detected was also different from the H5N1 avian influenza strain that is impacting the USA and other parts of the world.

Following confirmation of the first property, a control order under the Livestock Disease and Control Act 1994 was established including a restricted area extending approximately 5km around the impacted property and a control area in the eastern portion of the Strathbogie Shire to prevent movements that could spread the virus.

Following tracing activities, known connected properties were placed under quarantine and prioritised for testing. With the confirmation of a second property, a housing requirement was introduced for producers with more than 50 poultry in the restricted area. Two more closely related properties were confirmed with HPAI over a 2.5-week period.

Clinical signs reported included depressed birds, pale combs, open mouth breathing and weakness/neurological signs.

Following depopulation, disposal and decontamination efforts, the virus has now been eradicated from all the properties. The AgVic response effort included safely disposing of approximately 600,000 birds and 8.5 million eggs, removing 6,000 tonnes of waste and cleaning and disinfecting 21 sheds, all while maintaining strict biosecurity controls.

Following the successful eradication of H7N8, on 7 July, the World Organisation for Animal Health (WOAH) published a declaration from the Australian Chief Veterinary Officer, Dr Beth Cookson, confirming that HPAI is no longer present in domestic poultry populations in Australia. This milestone officially closes the outbreaks reported across Victoria, New South Wales, and Australian Capital Territory in 2024 and 2025, and showcases the extraordinary efforts of our teams who worked closely with community and industry.

A total of 977 laboratory submissions and 20,600 samples were collected over the 130-day response period, reflecting a coordinated surveillance effort involving AgVic and private veterinarians, supported by animal health officers.

• Putting your hand up is a great way to share your expertise, develop new skills, and help safeguard Victoria’s agriculture sector.
• Sound interesting? Find out more 👉 agriculture.vic.gov.au/privatevets.

Figure 2: Staff member undertaking a biosecure entry to an infected property during the 2025 H7N8 Euroa outbreak.

Figure 3: Mobile lab setup during the 2025 H7N8 Euroa outbreak.

The Animal Health Committee (AHC) national policy on the use of avian influenza vaccines for the protection of rare, protected and valuable avian species provides guidance on emergency vaccination of rare, protected and valuable avian  species against high pathogenicity avian influenza (HPAI).

A suitable vaccine (Zoetis Avian Influenza (AI) H5N1 Killed Virus) to protect avian species against HPAI H5N1 has been identified and is now available for use in Australia, under an emergency use permit granted by the Australian Pesticides and Veterinary Medicines Authority (APVMA).

The Zoetis AI H5N1 vaccine is available for administration prior to 31 December 2025.

The Department of Agriculture, Fisheries and Forestry (DAFF) is also exploring alternative vaccines which may be suitable for use in Australia and could be made available in future.

Agriculture Victoria would like to engage with people interested in vaccinating their rare, protected and valuable avian collections.

All avian influenza vaccine administration requires prior approval by the Chief Veterinary Officer (CVO). The vaccine itself will be available free of charge for eligible applicants, however stakeholders/groups will be responsible for all costs associated with movement and administration of the vaccine.

The following requirements must be met prior to vaccination with the Zoetis AI H5N1vaccine:

• birds must be greater than 150 grams AND more than 3 weeks of age
• populations must be kept in captivity or be closely managed to allow re-capture and identification of individual birds
• two doses of 0.5ml subcutaneous injection to be administered 4 weeks apart
• less than 50% of a species population is vaccinated at any one location
• a biosecurity plan must be implemented prior to vaccination. This plan must include biosecurity practices which reduce the risk of disease spread into the population of birds and state the agreed arrangements with a supervising veterinarian
• birds can only be vaccinated by a registered veterinary practitioner
• the nominated supervising veterinarian is responsible for endorsing and overseeing the vaccination protocol, maintaining vaccination records and supervising post-vaccination evaluation
• birds must be monitored for adverse effects for a minimum of 14 days after vaccination
• comprehensive record keeping of vaccinated birds must occur including vaccination date, individual identification information, results of individual health assessments including any illnesses, and all other monitoring activities.

It is noted the vaccine is not for use in domestic (commercial or backyard) poultry including emus.

Vaccine access may be prioritised within the rare, protected and valuable avian populations. Priority birds would include:

• threatened endemic and non-endemic Victorian species e.g. bird species listed in the Environment Protection and Biodiversity Conservation Act (1999) (EPBC Act)
• threatened non-native species of international importance e.g. bird species listed in a threatened category of the International Union for Conservation of Nature (IUCN) Red List
• populations or individuals that are otherwise considered as rare or valuable, for example due to: 

                o educational importance
                o significant investment in resources
                o genetically valuable such as non-poultry species listed under the
                   Rare Breeds Trust of Australia.

If you have a collection of birds that you would like to vaccinate using the Zoetis AI H5N1 vaccine and you can meet all of the above criteria, please contact cvo.victoria@agriculture.vic.gov.au.

This year has posed significant challenges for livestock feeding, with many producers resorting to grazing animals in unusual places and on unfamiliar vegetation. It is in years like this unusual disease events happen, as it did for an unfortunate farmer with suspected Lesser Loosestrife toxicity.

In autumn following the afternoon milking, a southwest dairy farmer moved 120 mixed-age dairy cattle onto the only green feed available; a dried-up swamp that was usually underwater and never previously grazed. The next morning, he discovered approximately 12 animals dead, while the remaining herd ranged from normal to slow-moving and trembling. The cattle were immediately moved to a known safe paddock with ad lib hay and lick blocks, and local veterinarians were called.

Multiple vets attended the property and found a number of downer cows displaying clinical signs consistent with grass tetany (magnesium deficiency). The cows were treated with intravenous 4-in-1 solution, and many initially responded with several recumbent cow regaining the ability to stand. Unfortunately, the improvement was short-lived – affected animals quickly deteriorated again, and more cows became recumbent and died. At this stage, the District Veterinary Officer was called and a Significant Disease Investigation was initiated.

The local District Veterinary Officer and an Animal Health Officer immediately attended the property to assist with the disease investigation. Their activities included identifying pasture species from the swamp, collecting blood samples, performing postmortems, and gathering epidemiological information. During the visit the following observations were noted:

• standing animals were trembling and some were drooling
• aggression was observed in several standing animals but not all
• recumbent animals died very quickly
• some animals had blood in their eyes and from orifices. Anthrax ICT tests were immediately done and returned negative results
• carcasses appeared to bloat very quickly
• the primary post-mortem findings were hepatic lesions. Affected livers appearing darker, purple and mottled - consistent with acute hepatic toxicity
• all ages, breeds, sexes and physiological stages were affected
• by the time the District Vet Officer departed that afternoon, the death toll had reached 55 out of 120 animals.

Figure 4. Lesser Loosestrife identified in the paddock. Photo courtesy of Dr Liz Hancock

Simultaneously, our Animal Health Officer transported samples directly to the state laboratory (AgriBio) in Melbourne, where analysis commenced. The next day, our pathologist confirmed the animals had suffered from acute toxic hepatopathy consistent with Lesser Loosestrife Toxicity. AgriBio later verified the plant collected was indeed Lesser Loosestrife.

In total, 70 cattle died (from a herd of 150), with the majority of deaths occurring within the first 24 hours. As Lesser Loosestrife was not identified within the rumen of dead animals we cannot definitively say it caused the deaths, however it is highly likely. The 50 surviving animals have remained in the herd and have not exhibited any further clinical signs.

While this was a deeply distressing event for the producer, it underscores the importance of coordinated efforts between local veterinarians, district veterinary officers, pathologists, and animal health officers in responding quickly to complex and uncommon disease investigations.

If you notice sudden deaths or unusual signs when assessing livestock, contact your local veterinarian, district veterinary officer, or the Emergency Animal Disease Hotline on 1800 675 888.

Japanese encephalitis virus (JEV) is now considered sporadically and seasonally endemic in mainland eastern Australia. As a zoonotic disease of significance to both human and livestock health, Agriculture Victoria undertook a suite of surveillance activities during the 2024–25 summer/mosquito season to better understand JEV circulation.

While clinical disease in pigs had been widespread in northern Victoria in 2022, the disease was not seen in livestock in 2023 and 2024. The disease was confirmed on 2 Victorian farms in 2025.

From chew ropes to effluent ponds, this season’s JEV surveillance combined innovation with proven methods to build a stronger picture of JEV activity in Victorian pigs.

Oral fluid surveillance at piggeries

Oral fluids collected via chew ropes offer a non-invasive and practical way to sample large groups of pigs, providing a representative snapshot of the herd. From late October 2024 to April 2025, a total of 691 oral fluid samples were collected across 6 participating high-risk farms.

Figure 5. Oral fluid collection via cotton chew ropes. Source: Agriculture Victoria

While all samples returned negative results for JE virus on PCR, one sample collected on 11 February tested positive for JEV antibodies – marking the first detection in Victoria in 3 years of oral fluid testing. Although not definitive, the findings suggest JEV exposure and highlight the challenges of antibody surveillance in the presence of cross-reacting flaviviruses.

Despite only a single positive result, this was a noteworthy milestone, confirming proof-of-concept for oral fluid-based JEV surveillance. Positive oral fluid samples were also reported in Queensland herds in 2025, where wetter, more humid conditions supported increased mosquito activity.

Environmental water and pig effluent sampling

A key innovation this season was the adaptation of wastewater testing technology – originally developed for COVID-19 – by CSIRO Dutton Park researchers. This method was repurposed to detect JEV in pig effluent and freshwater samples from high-risk areas.

Using simple dip sampling techniques from piggery sumps or effluent ponds, this approach requires minimal resources and no specialised field personnel. It enables efficient monitoring of large pig populations through single, representative samples.

Figure 6. Sampling pig effluent allows for broad herd-level surveillance in a single test. Source: Agriculture Victoria

Over the season, 55 effluent samples were collected across 6 farms, with JEV detected in 20% of these samples. Notably, the method identified viral presence on 2 farms without any reported clinical disease in litters and confirmed infection on the 2 farms where clinical signs were observed. One farm demonstrated the value of effluent testing as an early warning system, with multiple positive samples detected prior to the emergence of clinical disease.

These findings highlight the value of effluent-based surveillance in detecting both clinical and subclinical JEV circulation. The simple sample collection and sensitivity make it a promising method for broader implementation in future seasons.

Serological surveillance of finisher pigs at slaughter

Australian Pork Limited (APL), the industry body for the pork sector, funded 12 weeks of post-slaughter blood sample collection and antibody testing of pigs from two herds from each of the eastern states.

While all samples from Victoria returned negative results, positive detections were recorded on some farms in Queensland and New South Wales. These findings suggest testing individual blood samples from a small number of farms may not be a cost-effective or sensitive method for detecting low-level JEV circulation – particularly in areas like Victoria where virus activity appeared low this season.

Opportunistic feral pig surveillance

Parks Victoria undertook active feral pig baiting and trapping operations across some national parks and reserves in the north of the state. In collaboration with Agriculture Victoria, opportunistic sample collection from feral pigs was carried out to support broader disease surveillance efforts.

During the 2024–25 season, 6 trapping events were conducted in Barmah National Park, Indigo Valley, and Hattah-Kulkyne National Parks. Blood and tissue samples were collected from euthanised pigs, with preliminary results providing serological evidence of JEV circulation within feral pig populations in high-risk areas.

Significant Disease Investigations (SDIs)

Throughout the season, producers and veterinarians maintained a high level of vigilance for JEV. Between early November and mid-June, 19 disease investigations were conducted across 14 farms. Of these, 3 investigations – 2 of which were on the same property – returned positive results for JEV via PCR testing.

Figure 7. JEV Positive litter from the 2021/22 outbreak clearly showing stillborn and mummified piglets with obvious deformities (For more information: Japanese encephalitis information for vets – Pigs) Source: Sandy Adsett JBS Pork Australia Veterinarian

Looking ahead

This season’s surveillance efforts have laid the groundwork for smarter, more responsive JEV monitoring. By combining innovative tools with industry-wide collaboration, we’re better equipped to detect, understand, and respond to JEV activity – whatever future seasons may bring.

Acknowledgements

Agriculture Victoria extends its sincere thanks to all producers, piggery staff, veterinarians, and collaborators involved in JEV surveillance this season. Your dedication, vigilance, and collaboration are highly commended and continue to play a vital role in protecting animal and public health.

Pigs exhibit a wide range of neurological conditions, many of which are associated with specific age groups. This article discusses a fairly common syndrome in neonates – Congenital Tremors - as well as the distinct neurological presentation associated with Japanese encephalitis, as described by Dr Pedro Pinczowski, Senior Veterinary Pathologist, NSW Primary Industries, EMAI and another interesting case described by AgriBio pathologists Dr Mark Hawes and Dr Christina McCowan.

Congenital Tremors is a disease of newborn piglets that appears as bilateral, clonic contractions of the skeletal muscle that cease when the piglets are at rest or sleeping. This YouTube link illustrates the condition. Note: the cause of the infection in this litter is not described, but it is a good example of the condition. In this case you can see all the piglets appear to be affected, at 2 days of age they appear to be in excellent condition and able to suckle. The condition appears to resolve itself by 3 months of age, though some progeny may continue to respond to external stimuli with shaking.

The syndrome was first described in the USA as early as 1922,  and in Australia in 1937, with cases now reported globally. Other names for the condition are 'myoclonia congenita', 'jumpy pig disease' or 'dancing pig disease'- the latter 2 referring to the characteristic trembling and jumping. The literature describes 6 different forms with identical clinical signs, designated AI to AV and B. Clinical signs consist of mild to severe tremors of the head and body, sometimes with ataxia. The A forms are associated with CNS hypomyelination, whereas the B form shows no associated lesions or recognised cause. 

Of the 5 A types, 2 are hereditary and not seen in Australia: Type AIII has been observed in British Landrace male piglets  and Type AIV has been observed in Saddleback and Saddleback/Landrace pigs. Type AV is related to chemical poisoning with Trichlorfon (with current Australian registrations include for use in fly control in piggeries).

Importantly, congenital tremors have been associated with congenital Classical Swine Fever (CSF) and Bovine Viral Diarrhoea Virus (BVDV) infections. CSF produces a broad range of clinical signs, including fever, abortions and stillbirths, but some piglets that appear to be normal at birth later develop tremors or wasting.

In Australia currently, the most likely diagnosis is Type AII congenital tremors associated principally with Atypical Porcine Pestivirus (APPV) which is endemic in Australia. It is typically only seen in a sow’s first litter or occasionally across a herd following an introduction of new breeding sows.

Another differential in neonates is shivering due to hypothermia and hypoglycaemia shortly after birth, however, in these cases, piglets respond positively to warmth and milk. A range of other viruses have been associated with the condition, including porcine circovirus Type II, astroviruses and another pestivirus (LINDA) but none of these have been consistently identified or reported worldwide.

Tremors are also seen in other conditions - for example, in the exotic disease, Aujesky’s disease, which presents with ataxia and convulsions in piglets at 2-3 weeks of age, but not in neonates. Additionally, tremors are listed among the symptoms of Teschovirus A and Porcine Reproductive and Respiratory Syndrome (PRRS).

During the Australian outbreak of Japanese Encephalitis in 2022, one of the clinical signs observed was the appearance of 'Shaker' pigs within affected litters. These were often seen alongside abnormal, stillborn, mummified and occasionally normal piglets. The shaker piglets were described as being dull, lethargic, uncoordinated, weak, with tremors and salivating. Unlike the fine tremors typical of congenital tremors, these piglets were unable to suckle. They were considered non-viable and commonly died or were euthanised.

As described by Dr Pinczowski at EMAI, “changes of affected piglets include dramatic gross abnormalities in the central nervous system. The severity and pattern of the lesions varies according to the time of infection, with infections in early gestational periods producing more severe changes. Main abnormalities include hydrocephalus, hydranencephaly, and spinal cord hypoplasia. Some animals can also present with skeletal abnormalities including arthrogryposis, scoliosis, or kyphosis, and marked circulatory disturbances such as anasarca, thoracic and abdominal effusions.

Histologically, lesions vary in accordance with the severity of the gross changes. The cerebral cortex is commonly the most affected area of the brain and is characterised by a non-suppurative necrotising encephalitis with gliosis, neuronal necrosis and loss, and abundant mineralisation.”
Interestingly, the EMAI pathology team found the majority of piglets positive for JEV that were born alive, had mild to no gross abnormalities in the brain (but did present with some histological findings), which means they were likely infected late in the gestation.

Another noteworthy neurological case was observed in Victoria in 2024, presenting with clinical signs similar to the shaker syndrome associated with JEV. In this case – affecting a single litter on a large farm - the experienced practitioner was alerted by the clinical signs and gross pathology and a Significant Disease Investigation was initiated. Subsequent testing ruled out JEV as the cause. Photos of the affected piglets are shown below.

Figure 8. Gross pathology of JEV affected piglets,  image courtesy of Sandy Adsett.

Pathologists at AgriBio reported the brains grossly showed reduction of the depth and number of cerebral sulci with flattening of the gyri – features consistent with pachygyria which is considered a less severe form of lissencephaly, a neuronal migration disorder.

Histopathological lesions were extensive and were summarised as dysplasia of all regions of the brain and cervical spinal cord with suspected hypomyelination in white matter tracts.

The pathogenesis of lissencephaly in other species is due to abnormal neuronal migration which occurs early on in gestation.

The causes of lissencephaly in other animal species and humans include hereditary genetic mutations and less commonly, viral, or toxic teratogens. The condition is extremely rare or rarely reported, in pigs.

These cases highlight the importance of considering a wide range of potential exotic and endemic causes when investigating neurological signs in piglets, to ensure early detection of significant exotic or emerging diseases.

Pedro De Oliveira Nogueira 1 , Carlo Pacioni 2 , Dave Ramsey 2 , Alison Gunn 3 , Lee F. Skerratt 1 

1  Veterinary Biosciences, Faculty of Science, University of Melbourne, Werribee, Victoria, Australia
2  Department of Environment, Land, Water and Planning, Arthur Rylah Institute for Environmental Research, Heidelberg, Victoria, Australia
3  Herd Solutions, East Gippsland, Victoria, Australia

Neospora caninum is a protozoan parasite that can infect several species. It can significantly impact the reproductive performance and long-term productivity of dairy herds. Until recently, little was known about its current prevalence or transmission patterns on Victorian dairy farms. Our study combined field diagnostics with modelling to better understand how the parasite persists in herds.

Study approach

Blood and milk samples were collected from over 1,000 animals across Gippsland dairy farms. Farms with known Neospora or that had a history of abortions were targeted. Multiple samples were taken from the same animal at key reproductive stages and analysed using commercial ELISA tests and PCR. Detailed animal data such as age, pregnancy outcomes, and colostrum source were collected. Animals were then classified as infected or susceptible. A mathematical model was developed simulating how Neospora spreads within a herd and how it responds to different control strategies.

Key findings

• Prevalence is high in some herds. Overall, 32.3% of animals tested were positive, with some herds exceeding 50%.
• Vertical transmission is the dominant route. Comparing dam-calf pairs, we estimated a 43% probability that infected cows passed the parasite to their offspring. Our data strongly suggest that vertical transmission alone is sufficient to sustain the infection within a herd over time frames that are likely to be relevant to the industry (5-10 years)
• Evidence of horizontal transmission was present but less frequent. 8.29% of previously negative dams became infected during pregnancy, and 8.23% of calves born to negative dams tested positive, suggesting occasional environmental or undetected horizontal exposure at a lower rate.

Modelling control strategies

Modelling allowed us to test different Victoria-relevant scenarios and their long-term impacts (Figure 9).

Figure 9: Projected Neospora caninum seroprevalence under different intervention strategies using a deterministic model. Strategies included Baseline, no change in management (BL), Test and Cull (TC), and Test New Animals (TN). Each strategy was evaluated under two herd replacement systems (External vs. Internal) and with or without enhanced biosecurity measures.

Modelling showed that controlling Neospora caninum works best when multiple strategies are used together. The most successful scenarios combined 3 key actions:

• testing animals, especially replacements
• removing infected cows from the breeding herd
• improving farm biosecurity measures.

Together, these measures consistently led to the greatest reduction in infection levels over time. By looking at how these strategies interact, our model gives us a realistic picture of what works on farms and highlights the importance of tailoring control efforts to each herd’s situation.

Conclusion

Neospora can persist in herds without obvious signs, silently reducing productivity. Identifying infected cows and their offspring is critical for:

• avoiding infected heifers as replacements
• supporting informed breeding and culling decisions
• preventing long-term maintenance of infection.

Interested in knowing more? Get in touch

If you’d like to know more or discuss your herd’s Neospora status in light of this research, we’re always happy to chat. Whether you’re a vet, farmer, or advisor, your experience and questions help us shape better tools and solutions.

Survey link: https://q.surveys.unimelb.edu.au/jfe/form/SV_6PTQFINUyT6Kg74

Contact: Pedro De Oliveira Nogueira (poliveiranog@student.unimelb.edu.au)

Acknowledgements: We thank all participating farmers, regional vets, and labs for making this research possible. We also acknowledge Agriculture Victoria and Melbourne Research Scholarship for funding this project.

Buruli ulcer, caused by Mycobacterium ulcerans, is an emerging disease of public health and veterinary significance in Victoria.

To support public health and improve understanding of disease epidemiology, Buruli ulcer will soon be added to Victoria’s list of notifiable animal diseases.

Veterinarians are encouraged to notify Agriculture Victoria of any suspected cases in wildlife or domestic animals and consider submitting samples through the Significant Disease Investigation (SDI) Program.

Figure 10. Mycobacterium ulcerans on a ringtail possum’s face

Overview

Also known as Bairnsdale ulcer, Mossman ulcer, or Daintree ulcer, Buruli ulcer is recognised by the World Health Organization as a neglected tropical disease. The condition is caused by Mycobacterium ulcerans, which produces a toxin called mycolactone. This toxin destroys skin cells and soft tissue, resulting in ulceration and inhibition of the local immune response.

Although primarily considered a human disease, characterised by progressive, painless destruction and necrosis of the skin, leading to the formation of ulcers, similar lesions have been confirmed in domestic animals and wildlife in Australia. Globally, Buruli ulcer is most prevalent in Africa, where severe cases can result in disabling contractures or death due to extensive skin loss.

In Australia, human cases were initially confined to south-eastern Victoria and parts of Queensland, including the Daintree and Capricorn Coast. However, cases have now been reported in the Northern Territory and coastal New South Wales. In Victoria, confirmed cases in humans, wildlife, and pets have occurred in East Gippsland, Phillip Island, Mornington and Bellarine peninsulas, around Western Port, Surf Coast, Greater Geelong, and inner-northwest suburbs of Melbourne.

Buruli ulcer is a notifiable disease in humans in Victoria, and case numbers are increasing annually (Figure 11). There were 107 cases reported in 2015, 363 cases in 2024, and 229 cases reported to the end of August 2025. Notifications to the Department of Health show a seasonal pattern, with diagnoses peaking in winter and spring—approximately 4.5 months after peak mosquito activity in summer.

Figure 11. Cases of Mycobacterium ulcerans reported to the Department of Health in Victoria (2004 to August 2025). Source: Public Health Event Surveillance System, Department of Health

Animal cases

Despite the sharp increase in human cases, there have been only 40 cases in animals reported to Agriculture Victoria between 2002 and the end of August 2025 (Table 1). The disease is currently not notifiable, so it is likely these reports represent only some of the animal cases.

Confirmed cases of M. ulcerans disease in Victoria have been documented in a range of species including dogs, horses, and wildlife but ringtail possums represent 80% of cases reported to Agriculture Victoria. Geographic location and seasonal distribution match the disease in humans (see Table 2 and Figure 12). 

Figure 12. Cases of M ulcerans disease reported to Agriculture Victoria 2002-2025

Epidemiology

The transmission pathways of M. ulcerans are not fully understood. In Africa, the disease has been associated with water sources, while in Australia it is linked to coastal environments. The bacterium has been detected in soil, water, vegetation, and in the faeces of Victorian possums, rodents, rabbits and foxes. Notably, no animal reservoir has been identified in Africa.

Mosquitoes are strongly suspected to play a role in transmission, although other routes, such as contamination of abraded skin during gardening, or via bites and scratches from animals, are also likely. The incubation period in humans may vary from a few weeks to several months.

Figure 13. Amended schematic of proposed Mycobacterium ulcerans transmission cycle in Victoria. 

Source: doi: https://doi.org/10.1371/ajournal.pntd.0012189.g006  Accessed: 17 October 2025

Clinical Presentation in Animals

Affected animals typically present with ulcerative skin lesions, most commonly on the face, limbs, or tail. The disease may be minor and self-limiting, or it may progress to larger non-healing lesions with systemic involvement affecting multiple body systems and organs.

Diagnosis

Diagnosis is based on clinical signs and laboratory confirmation. Acid-fast organisms may be detected in stained biopsy samples or smears. Polymerase chain reaction (PCR) testing is the most rapid, sensitive, and specific method for diagnosing M. ulcerans infection. The organism can also be cultured using specialised media.

Samples to collect:

• swabs (dry or in transport medium)
• fresh tissue
• paraffin-embedded fixed tissue sections.

Differential diagnoses

Lesions caused by M. ulcerans may resemble those resulting from trauma, mange, other mycobacterial or infectious agents, or malignant neoplasia. Accurate diagnosis is essential to guide appropriate management. 

Figure 14. Mycobacterium ulcerans infection of a mountain brushtail possum’s claw

Figure 15. Mycobacterium ulcerans on a ringtail possum’s tail

Treatment and management

In some wildlife species, such as brushtail possums, lesions may resolve without treatment. In humans and domestic pets, however, early diagnosis is critical. Untreated ulcers can lead to extensive tissue destruction.

Treatment generally involves long-term antibiotic therapy which may be combined with surgical intervention. Ringtail possums are highly sensitive to the adverse effects of antibiotics; iatrogenic disruption of normal gut flora can cause potentially fatal caecal stasis and dysbiosis so antibiotics should be used with caution in this species, and the duration of therapy kept to a minimum.

In cases of severe disease, euthanasia may be necessary for affected wildlife or pets. Any animal showing typical clinical lesions should be examined by a veterinarian.

Prevention for veterinarians

Anyone handling possums should use personal protective measures, such as wearing gloves, and promptly wash and disinfect any bites or scratches.

For more information on how to reduce the risk of infection please see: Better Health Channel

Surveillance and notification

Veterinarians are encouraged to submit samples from animals with suspected M. ulcerans infection. Contact your local senior veterinary officer to access the Significant Disease Investigation Program, which supports testing and investigation of unusual or significant disease events. For more information see: SDI Program, Agriculture Victoria Significant Disease Investigation (SDI) program | Animal diseases | Biosecurity | Agriculture Victoria

To support public health and improve understanding of disease epidemiology, Buruli ulcer will soon be added to Victoria’s list of notifiable animal diseases.

Notifications can be made using the Notify Now app, which allows submission of geo-tagged photographs, owner details, and Property Identification Code (PIC), or via the Disease Notification Form

(Disease notification form  [MS Word Document - 80.3 KB]), which can be emailed to cvo.victoria@agriculture.vic.gov.au

or posted to:

Chief Veterinary Officer
Agriculture Victoria
475–485 Mickleham Rd
Attwood VIC 3049

Further details: Notifiable Diseases – Agriculture Victoria

Further Reading

Department of Health, Victoria
Beating Buruli in Victoria 
LGA Surveillance Reports

Wildlife Health Australia
Wildlife Health Australia (2025) “Buruli ulcer and Australian wildlife – Fact Sheet”, published by Wildlife Health Australia, Canberra, available at Buruli ulcer and Australian wildlife – fact sheet

World Health Organisation 

Buruli ulcer (Mycobacterium ulcerans infection)

Key References 

Hobbs, E. C., Porter, J. L., Lee, J. Y. H., Loukopoulos, P., Whiteley, P., Skerratt, L. F., Stinear, T. P., Gibney, K. B., & Meredith, A. L. (2024). Buruli ulcer surveillance in south‑eastern Australian possums: Infection status, lesion mapping and internal distribution of Mycobacterium ulcerans. PLOS Neglected Tropical Diseases, https://doi.org/10.1371/journal.pntd.0012189

Hobbs, EC., Loukopoulos, P., Stinear, TP., Porter, JL., Lee, JYH., Whiteley, P., Skerratt, LF., Gibney, KB. and Meredith, A., (2024) Severe cases of Buruli ulcer (infection with Mycobacterium ulcerans) in common ringtail possums in Victoria adversely affect animal welfare. Australian Veterinary Journal. https://doi.org/10.1111/avj.13360

Mee, P.T., Buultjens, A.H., Oliver, J. et al. Mosquitoes provide a transmission route between possums and humans for Buruli ulcer in southeastern Australia. (2024). Nature Microbiol. https://doi.org/10.1038/s41564-023-01553-1

Muhi, S., Cox, V.R., O'Brien, M., Priestley, J.T., Hill, J., Murrie, A., McDonald, A., Callan, P., Jenkin, G.A., Friedman, N.D., Singh, K.P., Maggs, C., Kelley, P., Athan, E., Johnson, P.D. and O'Brien, D.P. (2025), Management of Mycobacterium ulcerans infection (Buruli ulcer) in Australia: consensus statement. Medical Journal of Australia. https://doi.org/10.5694/mja2.52591

Xu, R. W., Stinear, T. P., Johnson, P. D. R., & O’Brien, D. P. (2022). Possum bites man: case of Buruli ulcer following possum bite. Medical Journal of Australia. https://doi.org/10.5694/mja2.51505

Agriculture Victoria is currently partnering with Verian research to deliver a survey evaluating the surveillance capabilities of private veterinarians and the current Significant Disease Investigation program.

The project aims to identify and deliver any new initiatives, tools or program changes that could be made to improve surveillance capabilities of private vets.

Participants will be sought across a range of veterinary practice types, including rural, regional, periurban, telehealth and consultancy services.

We encourage vets to keep an eye out for invitations to participate, and involve yourselves in this valuable research.

Victorian animal health data is collected from a number of sources, including targeted surveillance activities, monitoring programs, disease control programs, diagnostic laboratories, livestock producers and field investigations conducted by Agriculture Victoria (AgVic) staff and private veterinary practitioners.

There were 1,895 disease events in livestock investigated in Victoria between 1 July 2024 to 30 June 2025 1.

The geographic spread of the investigations (Figure 16) and the most frequently reported diseases in each species are shown below (Tables 3-10).

In these tables below, cases of clinical disease where no definitive disease agent was identified were reviewed in the context of the surrounding circumstances, and exotic or emergency diseases were excluded where appropriate.

Figure 16. Location of livestock investigations by species between 1 July 2024 to 30 June 2025.

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1 Based on livestock disease investigations reported to Agriculture Victoria.

There were 1,037 disease investigations of cattle between 1 July 2024 to 30 June 2025.

Table 3 shows the most frequently observed cattle diseases in each region during the period.  It does not include 365 investigations where no definitive diagnosis was made.

Salmonellosis continues to be the most commonly diagnosed disease of cattle. 

Veterinary practitioners are reminded that Salmonellosis is an important zoonotic disease and appropriate PPE should be utilized when conducting investigations of suspect cases of salmonellosis or any other potential zoonosis.

Table 3. Most commonly diagnosed diseases of cattle - 1 July 2024 to 30 June 2025

There were 289 disease investigations in sheep reported to AgVic between 1 July 2024 to 30 June 2025.

Table 4 shows the most frequently observed sheep diseases during the period. It does not include 65 investigations where no definitive diagnosis was made.

Table 4. Most commonly diagnosed diseases of sheep - 1 July 2024 to 30 June 2025

There were 56 disease investigations in goats reported to AgVic between 1 July 2024 to 30 June 2025.

Table 5 shows the diseases observed in goats during the period. It does not include 24 investigations where no definitive diagnosis was made.

Table 5. Diagnosed diseases of goats - 1 July 2024 to 30 June 2025

There were 121 disease investigations of horses reported to AgVic between 1 July 2024 to 30 June 2025.

Table 6 shows the most frequently observed diseases during the period for each region.

It does not include 66 horse investigations where no definitive diagnosis was made or cases with pending results.

Table 6. Diagnosed diseases of horses – 1 July 2024 to 30 June 2025

There were 320 disease notifications or investigations of poultry reported to AgVic between 1 July 2024 to 30 June 2025 including 298 reports in chickens, 10 reports in ducks, 4 reports in geese, 12 reports in pigeons and 2 reports each in emus, guinea fowl, peacocks and turkeys.

The high number of poultry investigations reflects enhanced passive surveillance undertaken for Avian Influenza during the HPAI emergency responses. Further diagnostics were not always undertaken to reach a final diagnosis.

The most common diseases diagnosed are listed in Table 7. The table does not include 191 cases where no definitive disease agent was found.

Table 7. Most commonly diagnosed diseases of chickens - 1 July 2024 to 30 June 2025

There were 53 investigations reported to AgVic between 1 July 2024 to 30 June 2025.

Table 8 includes a list of the diseases diagnosed during the period. The table does not include 27 cases where no definitive diagnosis was made.

Table 8. Most commonly diagnosed diseases of pigs - 1 July 2024 to 30 June 2025

Early detection of an emergency animal disease threat is vital to preventing its spread. AgVic encourages and facilitates the reporting and investigation of suspect EADs.

There were 636 investigations to exclude suspect emergency or exotic diseases undertaken between 1 July 2024 to 30 June 2025.

Data is reported separately for livestock (Table 9) and companion animals and wildlife (Table 10).

Note some investigations exclude more than one EAD (e.g., animals tested for foot-and-mouth disease will generally also be tested for vesicular stomatitis).

The data includes clinical disease investigations by private and AgVic veterinarians.

Figure 3 shows the geographic spread of livestock, wildlife and companion animal investigations.

Table 9. EAD exclusion testing in livestock undertaken. (1 July 2024 to 30 June 2025)

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2 In February 2025, 4 properties in northern Victoria were diagnosed with high pathogenicity H7N8.

3 In 2025 2 commercial pig properties experienced reproductive issues in sows and subsequently had Japanese encephalitis confirmed.

4 In September 2024, an emu property in northern Victoria experienced a mortality event with Mycobacterium avium confirmed as the cause of disease.

Table 10. EAD exclusion testing in companion animals and wildlife (1 July 2024 to 30 June 2025)

Figure 17. Location of suspect EAD investigations of livestock by species (1 July 2024 to 30 June 2025)

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5 Both dogs had originated from the endemic area in northern Australia.

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