Epizootic Haemorrhagic Disease

Description

Epizootic haemorrhagic disease (EHD) is an arthropod borne viral disease of wild and domestic ruminants that is transmitted between hosts by species of Culicoides biting midges. EHD virus (EHDV) belongs to the genus Orbivirus, family Reoviridae and shares many characteristics with other members of the genus including bluetongue virus (BTV). Seven serotypes (1-2 and 4-8) of EHDV are currently recognised of which six have been detected in Australia (1, 2, 5, 6, 7 and 8). Disease due to EHDV has not been observed in Australia.

While EHDV is capable of infecting wild and domestic ruminants it has predominantly been associated with disease in feral deer, in particular white-tailed deer of North America. Severe clinical signs have also been observed in cattle infected overseas with the Ibaraki strain (EHDV-2) and more recently due to serotypes 6 and 7. Clinical signs when observed are similar to those of severe bluetongue in sheep and may range from peracute illness with death often occurring within 36 hours (particularly white-tailed deer) to more chronic with animals remaining unwell for several weeks.

More specifically, clinical signs reported in white-tailed deer include fever, anorexia, lethargy, lameness, respiratory distress, severe oedema of the head and neck, and ulcers and erosions in the oral cavity, rumen and abomasum; some animals develop extensive haemorrhages in many tissues including the skin and heart. In cattle, the disease is characterised by fever, anorexia, ulcerative stomatitis, swelling of eyelids, respiratory distress, nasal and ocular discharge, redness and scaling of muzzle and lips, lameness, erythema of the udder and difficulty swallowing  (Ibaraki disease). Like bluetongue, disease in NSW would be expected to occur in summer or autumn in animals with a history of being present in the bluetongue zone/ecological range of the Culicoides vectors.

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Diagnosis and tests available

Diagnosis

Diagnosis of disease is supported by history, clinical signs, pathology and confirmation of infection by PCR.

Tests available

Test
Sample(s) required
Days of the week
test is conducted
Turnaround time1

Epizootic Haemorrhagic Disease Virus Antibody AGID

Clotted blood (red top tube)

Batch Tested on Friday

Up to 7 days

Epizootic Haemorrhagic Disease Virus Real–time PCR

EDTA blood (purple top tube),

semen and fresh tissue

According to demand 2-3 days
Epizootic Haemorrhagic Disease Virus Isolation

EDTA blood (purple top tube),

semen and fresh tissue

According to demand2 4 Weeks
Epizootic Haemorrhagic Disease Virus Neutralisation Test (All Serotypes)

Clotted blood (red top tube)

Referred to AAHL Referred to AAHL
Histopathology examinationFixed tissuesMonday to FridayUp to 5 days

1 Turnaround times are provided as a guide only. For specific information about your submission please contact Customer Service.

2  Please contact Customer Service to discuss requirements before submitting samples for testing

Specimen requirements

Blood (without anti-coagulant)

  • 10ml of blood into a plain red top tube
    • Submit chilled

Blood (with anti-coagulant)

  • 10ml of blood into an ETDA purple top tube
    • Submit chilled

Fresh tissue

  • Spleen, lung and lymph nodes from post-mortem cases
    • Submit chilled

Fixed tissue

  • Cardiac and skeletal muscle and other tissues as indicated by gross examination
    • Submit fixed in neutral buffered formalin at a 10:1 ration of formalin: tissue