Michigan is experiencing outbreaks of Epizootic Hemorrhagic Disease (EHD) in deer

The current outbreak in Michigan is affecting wild White-tailed deer and animals in privately-owned cervid facilities with 4,310 confirmed and suspected cases reported in 27 counties as of September 21.

Officials with Michigan Department of Agriculture and Rural Development (MDARD) and Michigan State University’s Diagnostic Center for Population and Animal Health (DCPAH) confirmed that epizootic hemorrhagic disease (EHD) has been discovered in two privately-owned cervid facilities in Barry and Ionia counties. The Michigan Department of Natural Resources (MDNR) has created an online map that indicates the townships in each county where White-tailed deer have been reported dead, with EHD suspected in some cases and confirmed in others. As DCPAH continues testing animals that have been submitted to their facility, the total of dead deer as well as number of counties involved in the outbreak may increase.

EHD is an acute, infectious, viral disease that is transmitted from deer to deer through the bite of a small fly known as a midge. Only deer bitten by a midge carrying the virus will become infected. These insects cannot survive frost so the incidence of EHD generally peaks during late summer and rapidly decreases in numbers with the onset of frost.

EHD has actually been present in the United States for more than 50 years. In fact, since 1890 deer die-offs have occurred in various parts of the U.S. and Canada. The actual cause of these early die-offs was never confirmed although EHD was one of several diseases suspected. The first confirmed incidence of EHD in the U.S. occurred in 1955 with large outbreaks in both New Jersey and Michigan. Since that time, documented outbreaks have occurred regularly in several states and Canada. Where it is more common, deer seem to build up antibodies to the disease. Michigan deer have not developed such antibodies at this point. Although there have been periodic wild White-tailed deer die-offs attributed to EHD in several Michigan counties since 1955, it was not reported among domesticated deer in Michigan until 2006.

 Due to the extended hot and dry conditions much of the nation has endured this summer, there has been an increase of EHD outbreaks in many states. Because of this situation, in a recent MDARD press release, State Veterinarian Steven L. Halstead strongly suggested “owners of cervid facilities make themselves aware of EHD cases occurring in wild, White-tailed deer in Michigan and other states and take measures to manage biting insects around these valuable animals.”

 The disease has a high mortality rate and has no known treatment; currently, there is no effective means of controlling EHD.

Deer usually exhibit signs of illness about seven days after being bitten. Symptoms include loss of appetite, excessive salivation, weakness, rapid pulse and respiration rates, fever and unconsciousness. Deer are often sluggish, confused, lame, unresponsive to or afraid of humans once they become ill with the disease. Curiously, dead deer are often found near bodies of water as they try to cool themselves from fever. Most dead pass into a shock-state eight to 36 hours after exhibiting noticeable symptoms, soon lying down and eventually dying.

Because of its very high mortality rate, EHD can have significant effects on a local deer population, but statewide decline in deer populations have not been noted. This has led experts to believe that there is no long-term effect from EHD on wild deer herds. In addition, the disease cannot be transmitted from one animal to another by direct contact nor is there any evidence that humans can be infected.

Michigan residents who do find a dead deer they suspect may have died from EHD are urged to call the nearest MDNR wildlife office to report it. Owners of privately-owned cervid facilities who find sick or dead animals in their herd should submit them to DCPAH for a post-mortem exam. State law, in fact, mandates that animals in a privately-owned cervid facility that die from disease or injury be submitted for chronic wasting disease (CWD) testing as part of the state’s CWD surveillance plan.

With the recent cooler temperatures that will continue as hunting season approaches, hopefully the current outbreak of EHD in Michigan will subside. Sportsmen who generally hunt in an area that has experienced a significant outbreak this summer might consider hunting in a different location this fall to give their local herd a chance to recover. For up-to-date information about the health of the wild White-tailed herd in Michigan, visit the MDNR website.

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