Epizootic hemorrhagic disease

Test code: S0191 - Ultrasensitive detection of epizootic hemorrhagic disease virus by reverse transcription coupled real time PCR

Epizootic hemorrhagic disease (EHD) virus belongs to the genus Orbivirus. The virus mainly causes hemorrhagic disease of white-tailed deer (Odocoileus virginianus), but can also affect mule deer, bighorn sheep, elk and pronghorn antelope. The virus is very infectious and is found throughout the United States. The southeastern United States has EHD outbreaks every year with relatively few losses of animals. In the northern plains, minor disease losses are reported every year, but in some years, losses can be significant.

The mode of transmission of EHD in United States is primarily through a midge, Culicoides variipennis. The disease is normally not transmitted directly from one animal to another, but transmission through direct contact has been shown to be possible through experimental inoculation of virus-laden material from infected deer by subcutaneous, intramuscular, intravenous or oral routes. All documented outbreaks of EHD have occurred during late summer and early fall (August-October), and usually stop within two weeks of the onset of frost, which kills the midge vector.

Infected deer develop signs of illness about 7 days after exposure. The onset of the disease symptoms is very sudden. Infected deer initially lose their appetite and fear of humans, grow progressively weaker, often salivate excessively, develop a rapid pulse and respiration rate, and fever (affected animals frequent bodies of water to lie in to reduce their body temperature) and finally become unconscious. Bleeding and lack of oxygen in the blood result in a blue appearance of the oral mucosa leading to 'bluetongue' (often confused with the bluetongue disease). Eight to 36 hours following the onset of observable signs, deer pass into a shock-like state, become prostrate and die.

Initial diagnosis is often accomplished by observing symptoms of infected animals. Confirmation by culture of the virus has low sensitivity and long waiting time. However, molecular detection by PCR offers a highly specific, sensitive and rapid confirmation of the diagnosis (Wilson et al., 2009).

Utilities:

• Help confirm the disease causing agent
• Identify EHD virus carriers
• Help ensure that animal populations are free of EHD
• Early prevention of spread of the virus among animals
• Minimize human exposure to the virus
• Safety monitoring of biological products that derive from animals

References:
Wilson, W.C., O'Hearn, E.S., Tellgren-Roth, C., Stallknecht, D.E., Mead, D.G. and Mecham, J.O. (2009) Detection of all eight serotypes of Epizootic hemorrhagic disease virus by real-time reverse transcription polymerase chain reaction. J. Vet. Diagn. Invest. 21:220-225.

Specimen requirements: 0.2 ml whole blood in EDTA (purple top) tube, or saliva swab, or 0.2 ml semen, or 0.2 ml fresh or frozen tissue.

Contact Zoologix if advice is needed to determine an appropriate specimen type for a specific diagnostic application. For specimen types not listed here, please contact Zoologix to confirm specimen acceptability and shipping instructions.

For all specimen types, if there will be a delay in shipping, or during very warm weather, refrigerate specimens until shipped and ship with a cold pack unless more stringent shipping requirements are specified. Frozen specimens should be shipped so as to remain frozen in transit. See shipping instructions for more information.

Turnaround time: 2 business days

Methodology: Qualitative reverse transcription coupled real time PCR

Normal range: Nondetected