Epizootic haemorrhagic disease (EHD) is a viral disease of wild and domesticated ruminants. It can cause high rates of disease and death in certain deer species. Humans are not affected by the disease.

North and South America, Asia and Africa (including countries bordering the Mediterranean such as Israel, Turkey, Jordan, Morocco, Algeria and Tunisia) and Australia

Wild and domesticated ruminants. Classically, the disease affects white-tailed deer in North America. Cattle may also become clinically ill, whereas disease of small ruminants (e.g. sheep, goats) does not occur.

Transmission occurs via the sting/bite of insects (gnats). Unborn foals can be infected in the womb. In temperate zones, infection usually occurs in late summer/autumn, whereas in tropical zones it can occur all year round.

2-10 days

Clinical disease mainly affects certain deer species, but may also occur in cattle. Fever, oedema, respiratory and swallowing problems, bleeding, inflammation of the mucous membrane and hoof ligaments, lameness, lassitude may occur. Abortions and stillbirths also occur.

A specific therapy is not possible. Diseased animals can only be treated symptomatically.

Vaccines are used sporadically in Japan and the USA. These are live attenuated vaccines or inactivated vaccines.

Epizootic haemorrhage has not yet been reported in Austria or in other European countries.

Epizootic haemorrhage is triggered by a virus related to the bluetongue virus (EHDV), which is also transmitted by insects (gnats). The disease has not been observed in Europe so far, but is spreading increasingly as a consequence of climate change.

EHDV are non-enveloped viruses with double-stranded RNA, which are divided into 10 different segments. At least eight different serotypes are distinguished. EHDV is unstable at higher temperatures (inactivation at 50 °C and 3 h exposure time; or 60 - 121 °C and 15 min exposure time). Organic solvents such as ether and chloroform are relatively ineffective (unenveloped virus). Disinfectants based on ß-propiolactones, 2% w/v glutaraldehydes, acids, alkalis (2% w/v NaOH), 2-3% w/v sodium hypochlorite, iodophores and phenols are effective.

Symptomatology

EHD is an important differential diagnosis to bluetongue in deer. In cattle, bluetongue (BT), bovine viral diarrhea (BVD), foot-and-mouth disease (FMD), infectious bovine rhinotracheitis (IBR), vesicular stomatitis (VS), and malignant catarrhal fever (BKF) are considered as differential diagnoses. Sheep and goats do not become clinically ill.

Due to the unspecific symptoms, a laboratory diagnostic clarification is essential. The virus itself can be efficiently and very sensitively and specifically detected in real-time PCR. Similar to BTV, EHDV is also detectable in EDTA blood for a long time (> 50 days after infection). Antibodies can be detected in competitive ELISA from 10-14 days after infection.

Sample material required: EDTA blood and serum from live animals; spleen, lungs, lymph nodes, liver.