Japanese encephalitis virus detected in Australian pigs
Japanese encephalitis (JE) was recently detected in piggeries in Victoria, New South Wales, Queensland and South Australia. There are currently no confirmed detections in Western Australia and imports of live pigs to WA have been temporarily suspended. Movement controls have also been implemented for importation of pig semen into WA.
JE is a mosquito-borne disease primarily affecting pigs and horses. JE virus can also cause disease in people bitten by infected mosquitoes and is a rare but serious health concern. JE is not a human food safety concern.
The most common signs of JE in pigs are reproductive losses including abortions, mummified foetuses and stillborn or weak piglets. Occasionally pigs up to six months of age may show tremors and convulsions.
Most horses may only show mild signs and the disease may be unrecognised, however fever, decreased or no appetite, lethargy, wobbliness and lack of coordination may occur.
WA pig producers and horse owners are urged to monitor for signs of JE and report any suspect signs to a local private veterinarian, DPIRD veterinarian or the national Emergency Animal Disease Watch Hotline on 1800 675 888. DPIRD subsidies are available for the veterinary investigation and testing costs.
For more information on JE in animals, mosquito management and biosecurity practices, see our DPIRD webpage: Japanese encephalitis. For human health information related to JE, visit the Healthy WA website.
Recent livestock disease investigations
Seizures and sudden deaths in weaner Merino ewes in the Wheatbelt
- Five of 480 Merino weaner ewes died on a property in December, with a further seven displaying neurological signs including seizures and foaming at the mouth.
- The sheep had been grazing fresh oat stubble and were also getting 500g of lupins per head every other day.
- The vaccination status of the mob was unclear. The ewes were previously healthy and didn’t show any signs of disease.
- A local DPIRD veterinarian visited the property to conduct a disease investigation and collected tissue samples and rumen contents for testing by DPIRD’s laboratory.
- Testing of the rumen contents was positive for annual ryegrass toxicity (ARGT) leading to the conclusion that ARGT was the likely cause of disease.
- Animals with lead poisoning can also show similar signs.
- Testing for lead toxicity was negative. Lead ingestion by food-producing animals presents a risk to human food safety and access to export markets and must be reported.
Breathing issues and deaths in cattle in the South-West
- Two 18-month-old Angus heifers out of a herd of 80 were found to have died overnight on a property in the South-West. One week before that, there had been another, similar death and one more heifer with troubled breathing on the property that had since improved.
- The herd had been on oaten hay since their arrival about one month earlier. The herd had been vaccinated and drenched previously.
- A DPIRD veterinarian post-mortemed one of the heifers, and submitted samples for testing by DPIRD’s laboratory.
- Laboratory testing confirmed a severe pneumonia caused by the bacteria Pasteurella multocida was the cause of death in the heifer.
- Further testing of the bacteria itself excluded the variant that is responsible for the exotic and reportable disease, haemorrhagic septicaemia.
- Haemorrhagic septicaemia is a significant disease of cattle and buffalo with a very high death rate that occurs in tropical and subtropical regions. The disease has not been found in Australia, but it is important to be vigilant for the signs so that it can be responded to early.
- Disease investigations in these types of cases may qualify for a subsidised veterinary investigation – see the DPIRD webpage Surveillance incentives for WA livestock producers.
- If you see unusual signs or unexplained deaths, contact your local DPIRD veterinarian or the Emergency Animal Disease hotline on 1800 675 888.
Neurological signs and deaths in weaner piglets in the South-West
- Out of 14 recently acquired 12-14 week-old Duroc piglets, two showed neurological signs including sitting like a dog, collapse and seizures. Another four had previously died.
- A private veterinarian contacted DPIRD to investigate this case further after treatment with antibiotics was unsatisfactory. The vaccination history of the recently introduced weaners was not known.
- The private veterinarian performed a post-mortem of both weaners and submitted samples to the DPIRD laboratory for analysis.
- Laboratory testing revealed changes in the brain typically associated with a bacterial infection, but the type of bacteria could not be determined. Multiple exotic and emergency diseases of pigs, including classical swine fever and African swine fever, were ruled out in this case. Initial testing indicated that Japanese encephalitis was not present in these pigs and further testing is underway.
- Bacterial infections of the brain in weaner pigs may be associated with exposure to stress from husbandry procedures, transport or introduction to a new environment. Prevention strategies involve minimising stress in young pigs.
- Introduced pigs present the greatest risk of introducing disease to a herd. It is recommended that producers only buy stock from a single herd with a higher or comparable health status. Inspect all new stock upon arrival and at regular intervals after introduction.
- There are many emergency infectious diseases of pigs that do not occur in Australia. Keeping Australia free from these diseases is vital to help protect human and animal health, livestock production and continue to allow export market access.
Diseases to watch out for in late summer/early autumn
- Crownbeard flowers during summer and autumn in the Midwest region. It is drought tolerant and can grow quickly after rain.
- Stock with no previous exposure to the weed and with limited feed alternatives are most susceptible to poisoning.
- Grazing the summer weed can lead to a loss of appetite, lethargy, heavy breathing, frothing from the mouth and nostrils and sudden death.
- Read more on crownbeard toxicity
Water quality issues
- Livestock production levels can be affected by water contaminated with heavy metals and chemicals.
- Water quality can be reduced where the salinity is excessive due to evaporation over summer.
- Water points can become toxic with blue-green algae when the water temperature increases.
- Stock may refuse to drink water or drink a reduced amount when the water is poor, which reduces feed intake and growth rate.
- Water samples can be tested for salinity, pH and toxic blue-green algae at the DPIRD laboratory.
- Typically affects weaners and hoggets during late summer/autumn.
- More common in British breeds.
- Brought on by stressors such as entry to a feedlot, dust and cold stress.
- Acute signs include coughing, laboured breathing, discharge from the nose or just general ill-thrift.
DPIRD nationally notifiable disease investigations (October – December 2021)
Nationally notifiable diseases pose a significant threat to animal health in Australia as well as access to international markets. When DPIRD receives samples from animals displaying signs of disease similar to a notifiable disease, we undertake testing for these diseases. Data from these investigations help provide evidence that our State is free of these diseases and supports our access to markets.
In the last quarter of 2021 (October-December), DPIRD undertook 280 tests in 174 disease submissions for nationally notifiable diseases.
In 2021, DPIRD carried out over 1000 nationally notifiable disease tests on more than 650 submissions to investigate disease in animals with visible disease signs. (This does not include notifiable disease tests for export testing or general surveillance in well animals.) The most common nationally notifiable diseases investigated in 2021 in livestock are shown below.
Update on Johne’s disease in WA
Following the detection of Johne’s disease (JD) cattle strain (C-strain) in cattle in WA, the WA cattle industry agreed JD (C-strain) was not technically feasible or economical to eradicate. Consequently, regulation of JD in WA has been reduced and, in consultation with the relevant industries, WA’s livestock import conditions have been amended to reflect this. The new conditions came into effect on 17 January 2022.
All livestock moving into WA from interstate that are not going immediately to slaughter must meet the following requirements:
- All properties the livestock have resided on must have had no suspected or confirmed JD infection in any species of livestock during the five years prior to movement of the livestock (to be moved into WA) off the property(ies).
- The livestock to be moved into WA must not have had contact with livestock suspected or known to be infected with JD.
- Cattle vaccinated for JD must be identified with a three-hole punch (preferably administered in the outer third of the right ear) and recorded in the National Livestock Identification System as JD vaccinated.
Further information can be found on the DPIRD webpage: Forms for importing livestock into WA.
DPIRD encourages WA producers to review their approach to the risk of JD as part of their on-farm biosecurity planning. This review should include examining and implementing their own requirements for livestock to be introduced to their property from interstate and from within WA.
Whether you are sourcing camelids, cattle, goats or sheep from interstate or within WA, DPIRD encourages all producers to ask for a national health declaration.
- Resources to assist producers with biosecurity planning, including information on JD, on-farm biosecurity practices, risk reduction (including biosecurity plan templates and checklists), and information on national industry assurance programs, can be found on the DPIRD website at:
- JD in cattle: management in WA (includes a recorded presentation on JD)
- JD in cattle: frequently asked questions
- JD in cattle: regulatory controls
- JD in sheep
- JD in sheep: biosecurity practices and management options
Please contact your local DPIRD field veterinarian if you require more information.
WA Livestock Disease Outlook highlights the benefits of surveillance
Australia’s ability to sell livestock and livestock products depends on evidence from our surveillance systems that we are free of livestock diseases that are reportable or affect trade.
The WA Livestock Disease Outlook summarises recent significant disease investigations by Department of Primary Industries and Regional Development veterinarians and private veterinarians. Data from these investigations provides evidence that WA is free from these diseases and supports our continuing access to markets.
Find out more about WA's animal health surveillance programs.
Feedback and subscriptions
We welcome feedback. To provide comments, email email@example.com.