Rabbit haemorrhagic disease virus

Description

Rabbit haemorrhagic disease virus (RHDV) is a virus that typically causes a rapidly fatal disease in European rabbits (Oryctolagus cuniculus). There are two species of RHDV present in Australia (RHDV1 and RHDV2).  RHDV1 is used as a biological control agent to reduce the feral rabbit population in Australia. Strain v351 has been used since 1996, while strain K5 has been used since 2017.  Both the v351 and K5 strains are RHDV1.  RHDV2 was first detected in 2015 in Australia. It is currently the strain causing most of the deaths in domestic rabbits.

In most adult rabbits the disease progresses rapidly from fever and lethargy to sudden death within 48-72 hours of infection. The incubation period for the RHDV is between one to three days. Most rabbits will show no clinical signs of RHD but may have signs of haemorrhage on post mortem. The disease causes acute liver damage with resultant blood clotting abnormalities. Death occurs due to liver necrosis and/or internal haemorrhages. RHD has a mortality rate of 70 to 90% in susceptible rabbits.

All RHDV strains can spread easily by contact between infected rabbits (via faeces, urine, saliva, nasal and eye secretions and mating) and fomites including hay, food, clothing, shoes, people, cages, equipment, dust, insects, wild birds and rodents.

The RHDV1 vaccine (Cylap®) has been shown to be effective against RHDV1 strains v351 and K5. The vaccine is less effective against RHDV2 where protection is estimated to be between 60 and 70%.

Other control measures include

  • Preventing direct and indirect contact between domestic and wild rabbits.
  • Avoiding cutting grass and feeding it to rabbits if there is the risk of contamination from wild rabbits.
  • Wash hands, with warm soapy water between handling rabbits.
  • Good insect control is also important and will help reduce the risks of introduction of both RHDV and myxomatosis. Insect control could include insect proofing the hutch or keeping the rabbits indoors.
  • Infected rabbits should be isolated and disposed of in a manner that will minimise environmental contamination.

Estimating the prevalence of immune feral rabbits prior to release of the control strains is recommended. A high sero-prevalence in the rabbits is an indication that release of the virus is not likely to be successful in reducing numbers.

Diagnosis and tests available

Diagnosis

Diagnosis is based on clinical history and detection of RHDV.

Tests available

Test

Sample(s) required

Days of the week test is conducted

Turnaround time1

RHDV1 PCR (v351 and K5 strains)

Fresh liver

According to demand

2-3 days

RHDV2 PCR (RHDV2 strain)

Fresh liver

According to demand

2-3 days

RHDV antigen capture ELISA (v351 strain only)Fresh liverAccording to demandUp to 7 days
RHDV1 antibody ELISAClotted bloodAccording to demandUp to 7 days
Histopathology examinationFixed tissueMonday - FridayUp to 5 days

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

Specimen requirements

Fresh tissue

  • 1-5 grams of liver
    • Submit chilled (not frozen) in leak proof container

Blood (with anti-coagulant)

  • 1-2 ml of blood collected into a plain red top tube. Blood should ideally be collected from 8-10 feral rabbits from each proposed release site.
    • Submit chilled

Fixed tissue

  • Liver or spleen
    • Submit fixed in neutral buffered formalin at a 10:1 ratio of formalin: tissue