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Updates for KVMA By Allison Siu, DVM, MPH CDC, Veterinarian | Frontline Public Health Responder | Promoting and Advancing the Health of the Nation | Protecting the U.S. from Domestic and International Public Health Threats
Highly pathogenic avian influenza (HPAI) H5N1 virus is primarily known for its severe effects on wild
birds and poultry but has infected an increasing num- ber of non-avian species over the recent years and has been detected in poultry and mammals in Kentucky. Te current outbreak began in 2022 and is associ- ated with introduction from wild aquatic birds. In the past several years, there have been an increasing number of animal species infected by the virus, in- cluding both marine and terrestrial mammals. Since 2023, HPAI H5N1 wildlife detections in Kentucky have included waterfowl, raptors, a raccoon, and an American mink. On March 25, 2024, the United States Department of Agriculture (USDA) identified HPAI H5N1 for the first time in dairy cattle in Tex- as. To date, HPAI H5N1 has been confirmed in 192 herds across 13 states. Clinically, dairy cattle exhibit decreased milk production, thickened and discolored milk, inappetence, dehydration, fever, and lethargy, but can recover with supportive care. USDA has led efforts in responding to the current outbreak, with the goal of eradicating the virus in dairy cattle. A key part of these efforts includes conducting phylogenet- ic analysis and epidemiologic investigations to better understand the infection and transmission dynamics in non-avian species. Studies support that a single introduction into dairy cattle occurred followed by onward transmission, propagated by additional fac- tors including animal movement and insufficient bi- osecurity. Because of the highly contagious nature of the virus, improved biosecurity is key to mitigating the risk of disease spread on and between farms. En- hanced biosecurity measures that can be shared with farmers and producers includes limiting visitors, checking animals regularly for signs of illness, disin- fecting vehicles and equipment that may be shared between premises, utilizing separate boots and tools for different farm premises, avoiding mixing species, keeping livestock and pets away from birds, and iso- lating and reporting suspected HPAI-infected ani- mals to USDA.
Te current outbreak has required a multi-agency One Health response and includes additional federal partners working in coordination with state animal and public health officials. The Food and Drug Administration (FDA) continues to conduct studies
that demonstrate current pasteurization methods are effective in deactivating the virus in commercially produced dairy products. In addition to non-avian infection with HPAI H5N1, the virus is known to cause sporadic human infections with illness ranging from mild to severe. Te current outbreak has resulted in 14 human infections since 2022, 4 of which are linked to exposure to H5N1 infected dairy cattle, and the remaining 10 linked to exposure to H5N1 infected poultry. Human illness has been mild with symptoms ranging from fatigue to conjunctivitis and mild respiratory symptoms, and all cases have fully recovered. No person-to-person transmission has occurred in association with the current outbreak and the overall risk to the public remains low. However, those with occupational exposures (e.g. agricultural farm workers) are at higher risk of infection due to potential prolonged and direct exposure to the virus from infected animals. Individuals with occupational risk are encouraged to wear recommended personal protective equipment (PPE) when working with sick or dead animals, feces, litter, raw milk, or other potentially infected material. Te Centers for Disease Control and Prevention (CDC) continues to monitor the evolving outbreak and provide public health support and guidance to jurisdictions.
While outbreaks of HPAI have occurred in poultry in Kentucky in the past, there are currently no detections of the virus in cattle, poultry, or humans. USDA announced a federal order in April 2024 requiring HPAI H5N1 testing of lactating dairy cattle prior to interstate movement. Kentucky requires lactating dairy cattle to be tested prior to importation into Kentucky if coming from an HPAI H5N1 affected state. Furthermore, Breathitt Veterinary Center and UK Veterinary Diagnostic Laboratory are participating in HPAI surveillance testing in domestic cats. Due to the severe neurologic presentation in cats, domestic cats who have been submitted for rabies testing and test negative for rabies, are subsequently tested for HPAI. Clinicians should consider HPAI in cats with appropriate clinical history and neurologic signs and symptoms. Tus far there have been no HPAI positive cats identified in Kentucky.
Continued on pg. 20 Summer 2024 19
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