Recent Outbreaks
DEC is currently monitoring an outbreak of EHD affecting the lower Hudson Valley. The outbreak started in Orange County in mid-August 2024.
In 2022, a small and localized outbreak of EHD occurred in Dutchess County. In 2021, NY experienced its most severe outbreak of EHD, with >2,000 deer reported. The primary outbreak was concentrated in the lower Hudson Valley, but secondary outbreaks occurred along the eastern shores of Lake Ontario and on Long Island. In 2020, DEC received reports of >1,500 deer suspected to have had EHD throughout the lower Hudson Valley. Prior small outbreaks of EHD occurred in New York in 2011 and 2007.
Causes and Susceptible Species
EHD is a viral, often fatal, disease of white-tailed deer that is transmitted by biting midges (Culicoides spp.), also called no-see-ums or punkies. The disease is not spread directly from deer to deer and humans cannot be infected through contact with deer or bites from midges. EHD outbreaks are most common in the late summer and early fall when the midges are abundant. Deer that succumb to EHD do not serve as a source of infection for other animals because the virus is not long-lived in dead deer. Some strains of EHD can infect cattle. A similar viral disease called bluetongue (BTV) has also been detected in NY deer and can cause identical signs, BTV is also spread by midge bites and does not affect humans or pets.
Symptoms and Diagnosis
In deer, external signs of EHD include fever; small hemorrhages or bruises in the mouth and nose; and swelling of the head, neck, tongue, and lips. A deer infected with EHD may appear lame or dehydrated. Deer will begin to show signs 2 - 10 days after contracting EHD and usually die within 36 hours of showing signs of infection. Frequently, infected deer will seek out water sources and carcasses are often found in or near water. Deer that have died from EHD infection seem to bloat and decompose rapidly. A large number of dead or sick deer may be found in localized areas near water.
EHD resembles other serious but rare diseases of domestic ruminants including BTV and Foot and Mouth Disease, so it is important to confirm the diagnosis when outbreaks occur. Dead deer are examined by necropsy (animal autopsy) and tissues are tested for viral DNA to confirm the disease.
Management
The first hard frost kills most midges, effectively ending EHD outbreaks. EHD is endemic (occurs yearly) in the southern U.S. and it is becoming more common in the northern parts of the U.S. In some states, large outbreaks have affected thousands of deer. DEC tests and tracks deer mortalities to determine impacts on the deer population.
There is no treatment and no means of prevention for EHD. While EHD outbreaks can remove a number of deer from a local population, they generally do not have a significant long-term impact on regional deer populations. That’s because deer that survive EHD outbreaks can develop antibodies to the virus, making them more resistant to future outbreaks.
DEC does not remove dead deer; however, if there is a need to dispose of or move a dead deer, landowners should take routine precautions: wear gloves and wash hands afterwards. In rural and lightly populated suburban environments deer can be dragged to a wooded area to be scavenged and decompose. In heavily populated suburban and urban environments deer carcasses may need to be brought to a landfill or composting facility. Some Nuisance Wildlife Control Operators will dispose of deer carcasses for a fee.
For hunters, thorough cooking will kill the virus, but DEC always recommends against harvesting or eating any animal that appears sick or diseased. Hunters who are concerned that the deer they harvested had EHD can request a replacement carcass tag from their regional DEC office. The entire deer carcass, including antlers, will need to be surrendered to DEC in order to receive a replacement carcass tag.
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