#17,603
As we've seen previously, early reports of unusual deaths or illness (in humans, or in other animals) - even from reputable sources - often turn out to be exaggerated, or due to something relatively common.
A prime example, last September's Argentine MOH Investigation Into A Hospital Outbreak Of A Pneumonia Outbreak of Unknown Origin, turned out to be due to Legionella.
While genuine `novel' diseases do emerge (see here, here, here, and here), most outbreaks turn out to be due to something less exotic.
For the past 3 weeks we've been following reports of sudden horse deaths (n=17) in Victoria, Australia (see Australia: Agriculture Victoria Investigating Sudden, Unexplained Horse Deaths).
Given the past history of horse (and rarely, human) deaths from the Hendra virus, this immediately raised concerns, but early testing ruled that bat borne henipavirus out as a cause. Additional testing for diseases, and toxicology, continued.
As we learn now from Agriculture Victoria - while no definitive cause has been established - these deaths are now regarded as unrelated, and not due to any infectious disease.
Sudden horse death investigations
2 August 2023
Investigation concludes
Agriculture Victoria has confirmed that recent sudden multiple horse deaths are not linked or the result of an infectious disease.
Sample testing and necropsies were conducted where possible on deceased animals and found nothing unusual or unexpected as contributing causes.
A number of separate diagnoses have been made including intestinal issues in one instance, while there is a possibility of toxic plants present in another.
In some instances it was not possible to determine a clear cause due to a lack of available suitable samples.
The investigation involved a total of 17 horses that died on six separate properties where multiple deaths were reported.
Negative tests were returned for a wide variety of transmissible diseases such as Hendra virus and equine influenza.
We would like to thank the horse industry, private veterinarians, other experts and horse owners for their assistance during this investigation.
Next steps
As there are no further concerns about the investigation’s findings, regular arrangements for reporting illness or deaths in horses will be reinstated.Private veterinarians must be the first point of contact as your horse’s primary health advisor – they are the ones with specific knowledge about your individual situation and best placed to provide assistance and also where to find other assistance if required. .
Agriculture Victoria can support private veterinarians via the Significant Disease Investigation (SDI) program if eligible.
All horse owners should take regular steps towards ensuring the best health of their horses and tailored to the season, including good parasite management and weed control, and providing quality feed and water.
Further information:
Plants Poisonous to Horses: An Australian Field Guide
Caring for horses during winter
Basic horse care
Horse health and welfare
Investigation procedures for vets
FWS Update: California Condor H5N1 Vaccination Trial
FWS Update: H5N1 Vaccine To Be Tested Next Week On 3 Captive California Condors
USFWS & USDA Update On Impact of H5N1 on Condors & The Potential Use of HPAI Vaccines
While nearly extinct by the late 1970s, a successful breeding and release program has increased the global population of California Condors to nearly 500. Last Friday's update follows:
California Condor HPAI Response Update - August 4, 2023
Aug 4, 2023
The U.S. Fish and Wildlife Service’s Incident Command Team, in collaboration with partner agencies, continues to develop and implement conservation strategies to help California condors in light of Highly Pathogenic Avian Influenza (HPAI). Strategies include implementation of vaccine trials, field monitoring, and adaptation of current management practices to be increasingly nimble and flexible to improve response to future HPAI outbreaks.
Incident Update
Black Vulture Vaccination Trial Results
Titers (concentration of antibodies) present in the birds are in the final stages of being evaluated by USDA’s Southeast Poultry Research Laboratory. Results will be reported soon.
California Condor Vaccination Trial
Vaccination of condors in managed care continues. Blood samples from the birds will be collected at 21-days and 42-days following vaccination to evaluate the immune response from two different vaccination approaches. The first sample will be collected on August 8 and the second samples August 15. These samples will be batched together for analysis. Trials will run into September.
Group 1: Vaccination of 0.5ml on two occasions, 21 days apart (initial injection and booster).
Status: 10 condors administered first dose of 0.5ml vaccine.
Group 2: Single vaccination of 1ml.
Status: Six condors administered single dose of 1 ml vaccine.
Group 3: Control birds, no vaccinations, only blood sample collections.
Ongoing Field OperationsThree of the birds that were rescued, condors 982, 1061, and 1108, received care for HPAI in Arizona and are ready to be released back into the wild. Blood samples evaluated by USDA’s National Veterinary Services Laboratory show that all three birds have some level of natural immunity to HPAI after contracting and surviving exposure to the virus. The birds are in The Peregrine Fund’s release pen at the Bureau of Land Management’s Vermillion Cliffs acclimating to the wild. Pending weather and their behavior, they will be released on Saturday, August 5, 2023. Updates will be provided on The Peregrine Fund’s social media pages. The fourth bird, condor 757, that survived also has immunity to HPAI and will be released at a later time as he is currently re-growing molted flight feathers.
Due to the effects of Highly Pathogenic Avian Influenza on the Arizona/Utah condor flock, the U.S. Fish and Wildlife Service, The Peregrine Fund, Bureau of Land Management, Vermilion Cliffs National Monument, and other Southwest Working Group condor partners are not holding the annual Public Lands Day condor release. Instead, the BLM and partners will host a National Public Lands Day event on Saturday, September 23 to improve the Vermilion Cliffs National Monument condor release viewing site in preparation for the highly anticipated 2024 condor release. The event will be a service project that will allow public land and condor enthusiasts to work with biologists from the Southwest Condor Working Group on a project to benefit condors. For more information, please visit the BLM’s press release.
We are probably still several weeks away from knowing how much of an immune response these vaccines will have on these endangered birds.
