Epizootic Hemorrhagic Disease Virus

Virus, Non-Enveloped

VirusEpizootic Hemorrhagic Disease Virus
StructureNon-enveloped
GenomeDouble stranded RNA
FamilyReoviridae
Primary HostRuminants
Disease(s) CausedEpizootic Hemorrhagic Disease
SymptomsHigh fever, edema of neck and head, hemorrhaging, ulcers
Potential ComplicationsMalnutrition, lameness
Transmission ModeBiting midges
Sites of Community OutbreaksWhite-tailed deer populations

Importance of Epizootic Hemorrhagic Disease Virus

Epizootic Hemorrhagic Disease Virus (EHDV) is a non-enveloped member of the Reoviridae family. EHDV causes Epizootic Hemorrhagic Disease (EHD) in wild and domestic ruminants in North America, Asia, Australia, and Africa.

EHD is most commonly found in white-tailed deer. It presents as three different forms: peracute, acute, and chronic, in order of severity. Symptoms of peracute EHD include high fever, respiratory distress, weakness, and rapid and severe swelling of the head and neck. This syndrome progresses quickly, with 100% mortality within 8-36 hours after the onset of symptoms.

The acute form is known as 'classic' EHD. Symptoms of the acute form include those of the peracute form and also include ulcerations of the mouth and rumen, as well as extensive hemorrhaging throughout the body. Both the peracute and acute forms have a high mortality rate, although the overall severity differs from outbreak to outbreak depending on the strain involved.

Deer which develop the chronic form typically recover gradually after a long illness. EHD can cause the hoof to stop growing as it should. Some animals may lose the hoof wall or toe. This can greatly hinder their ability to walk, and some animals have been found crawling on their knees. The chronic form of EHD can also cause malnutrition and emaciation due to damage to the rumen.

EHD can also affect other ruminants. Outbreaks in cattle occur but are rare and usually associated with an outbreak in deer. Most infections are subclinical and show no symptoms. Symptoms in cattle are much less severe than those seen in deer. These include fever, loss of appetite, drop in milk production, lameness, and oral ulcers. These symptoms can closely match those of several other important diseases of cattle, such as bovine viral diarrhea, foot-and-mouth disease, and vesicular stomatitis. Therefore, cases of EHD in cattle are often reported to state health authorities for further investigation. Cattle typically recover within a few weeks of the onset of symptoms.

Transmission and Disinfection

EHDV is transmitted by an insect vector, typically a biting midge of the genus Culicoides. It is not known to be spread directly from animal to animal. Insect control is crucial to preventing the prevalence of EHDV. This can be accomplished by removing potential breeding areas and using insecticides and repellents.

As with most non-enveloped viruses, EHDV is resistant to many disinfectants. It is, however, susceptible to 2-3% sodium hypochlorite and 2% glutaraldehyde solutions.

References
  • "Diseases Caused by the Epizootic Hemorrhagic Disease Virus Serogroup." The Center for Food Security and Public Health, Iowa State University, Mar. 2006. Web. 29 Jan. 2016.

  • Stevens, G. et al. “Review of the 2012 Epizootic Hemorrhagic Disease Outbreak in Domestic Ruminants in the United States.” Ed. Martin Beer. PLoS ONE 10.8 (2015): e0133359. PMC. Web. 29 Jan. 2016.