August 26, 2020

PIERRE, S.D. – South Dakota Game, Fish and Parks has documented the first deer mortalities in 2020 due to hemorrhagic disease, also known as epizootic hemorrhagic disease (EHD) or blue tongue. EHD was recently confirmed by laboratory analysis in deer from Hughes and Sully counties.

This disease is common in white-tailed deer and is typically detected in late summer or early fall. Minor deer losses to EHD can occur in any given year in South Dakota, but weather and habitat conditions will dictate the severity of the disease. EHD is not infectious to humans. For more information on the EHD virus visit

The virus is spread by a biting midge and causes extensive internal hemorrhaging in infected animals. Many deer exhibit no clinical signs and appear perfectly healthy, while others may have symptoms such as respiratory distress, fever, and swelling of the tongue. With highly lethal strains of the virus, deer can be dead within 1-3 days. Affected deer are often found near low lying areas or water, likely due to the deer attempting to combat the high fever.

With fall approaching, landowners and hunters will be in the field and may encounter such mortalities. GFP asks anyone who observes sick deer or finds several dead deer in a localized area to contact their local conservation officer or GFP office . This information is valuable to wildlife managers in monitoring deer populations across the state.

EHD outbreaks can be locally severe, but rarely affect a high proportion of the deer population in a management unit. In 2016, the disease affected deer populations in certain areas of eastern South Dakota and license adjustments were made in some management units to react to these unforeseen mortality events. Deer can continue to succumb to this disease until a hard freeze reduces the midge populations that carry the disease.