More often, deer survive longer and may become lame, lose their appetite, or reduce their activity.
With highly virulent strains of the virus, deer may die within 1 to 3 days.
The onset of freezing weather, which stops the midges, brings a sudden end to HD outbreaks.
How the viruses persist through the winter when midges are not active is not clear. Outward signs in live deer depend partly on the virulence (potency) of the virus and duration of infection.
Outbreaks tend to last until the first frost of the season kills the flies.
DGIF provided the following information about hemorrhagic disease. HD is the most important infectious disease of white-tailed deer in the Southeast United States and in Virginia, and outbreaks occur almost every year. HD is caused by two closely related viruses, epizootic hemorrhagic disease (EHD) or bluetongue virus.