Illinois EHD Outbreak Summary for 2013

Chris McCloud
Illinois EHD Outbreak Summary for 2013
EHD (Epizootic Hemorrhagic Disease) appeared across the state of Illinois again in 2013, though reports don�t appear to be as severe or extensive as in 2012.  The Illinois Department of Natural Resources (IDNR) received a total of voluntary 318 reports from concerned landowners and hunters totaling 1,220 dead deer from 63 counties.  2012 was the worst year for EHD in Illinois, with 2,968 dead deer reported to IDNR from 87 counties. 

EHD is a viral disease, spread by biting gnats, which can cause high fever and severe internal bleeding in deer.  While often fatal to deer, EHD is not hazardous to humans or pets.  EHD-like symptoms in cattle have been reported where EHD has been confirmed in deer.  Cattle can be successfully treated with medications.  EHD is often confused with bluetongue, a similar disease that can affect sheep and cattle.

The disease was most prevalent this year in the western half of the state, from approximately St. Louis north to the Wisconsin state line.  Heaviest hit counties included Fulton (197 cases), Jo Daviess (126), Woodford (91), Adams (88), and LaSalle (75). 

EHD does not impact deer populations evenly across the landscape.  A mixture of deer combined with the presence of the virus and midges (biting gnats) that transmit the disease between deer are necessary for an EHD outbreak to occur.   Heavy deer mortality can be observed on one farm, while the farm down the road will be hardly affected. 
EHD affects bucks as well as does, adults as well as fawns and yearlings, though individual deer vary in their susceptibility to the virus.  Some deer become infected and will be dead within 48 hours, while other deer will be minimally affected.  Survivors of infection develop immunity to the virus.

Dead deer are often found near water sources such as lakes, ponds, or streams, though a deer carcass found away from water is also likely to have succumbed to EHD.
EHD related mortality occurs every year, but becomes more severe during droughty conditions.  Limited water sources concentrate deer near exposed mudflats resulting from receding water levels.  Midges hatch from these exposed muddy areas resulting in abundant insect populations.   There is no effective management treatment for this disease.  EHD outbreaks end when a heavy frost kills the midges necessary for transmission.

Persons wanting more information about the EHD outbreak in Illinois are encouraged to contact Doug Dufford, Wildlife Disease and Invasive Species Program Manager with IDNR.  He can be reached via email at or by phone at 815-369-2414. 

A table showing the number of reports and cases by county, and maps showing the distribution of EHD-related deer mortality reports in Illinois for 2013 and 2012 are also presented at this link on the IDNR website:
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