EHD Hits Northeast

The Delaware Division of Fish & Wildlife is reassuring residents and hunters that an insect-borne disease that has been killing whitetail deer throughout North America does not affect humans, does not affect livestock and has minimal long-range ramifications for the viability of the state’s deer herd.

Epizootic hemorrhagic disease (EHD) is transmitted by small biting flies commonly called midges or “no-see-ums.” EHD is the most significant disease afflicting white-tailed deer in North America but is also the best known and the most widely studied, having first been identified in 1955 with regular, almost annual outbreaks since. EHD outbreaks are most often associated with periods of drought. All known outbreaks have occurred in late summer and early fall, and are abruptly curtailed with the onset of frost, which kills the midges and suspends the hatch of their larvae.

EHD outbreaks are common in Delaware and other Mid-Atlantic states, with the last significant outbreak occurring in 2007 with more than 132 dead deer reported in Delaware.

Delaware’s statewide losses have been relatively light this year, with 31 dead deer reported so far. Other northern states have already reported losses in the hundreds. “One positive outcome of having periodic outbreaks of EHD such as those that occurred in 2007 and 2010 is that our deer have a chance to develop antibodies to fight the disease. Deer having this resistance to EHD helps prevent large-scale losses,” said Rob Hossler, Game Species Program manager with the Division of Fish and Wildlife.

Deer have died from EHD in all three counties in Delaware, but mortality has been most concentrated in Sussex County, outside Georgetown and Milton. “We expect hunters and landowners will report more dead deer in more widespread areas as they venture into the woods for the Sept. 1 start of deer archery season,” said Joe Rogerson, Division game mammal biologist.

Humans cannot be infected by EHD, nor can the disease be transmitted by consuming venison from afflicted animals. However, hunters are advised to avoid eating venison from visibly sick deer because they may be stricken by a secondary infection that could affect people.

There is no known effective treatment for EHD, nor can white-tailed deer be vaccinated against the disease, although deer do build-up antibodies to the disease. No pesticides can be sprayed to kill the insects that cause EHD. “We are in a position of allowing nature to run its course and waiting for a hard frost to kill the midges,” said Rogerson.

EHD is known for its sudden onset, and its symptoms in deer resemble another sickness, chronic wasting disease, or CWD, which is not yet known to have occurred in Delaware. Afflicted animals exhibit pronounced swelling of, and bleeding from the head, neck, tongue, eyes and rectum. Deer lose their appetite and fear of humans, grow progressively weaker, salivate excessively and finally become unconscious. Due to a high fever, infected deer often are found sick or dead along or in bodies of water.

The virus deteriorates less than 24 hours after a deer dies, and cannot be spread from carcasses. Landowners may allow natural deterioration of carcasses in the field, but are advised to remove them from ponds or streams to prevent other contamination issues. Property owners are responsible for proper disposal of carcasses that they choose to remove; carcasses can be disposed of at landfills that accept household solid waste.

The Division of Fish and Wildlife is documenting deer mortality for research purposes and to obtain data for future references to EHD.

Anyone finding a dead deer with no apparent cause of death is asked to report the finding to the Division by calling 302-735-3600.