Rabies (lyssavirus)

Microbiology

Notes

• Rabies is an acute viral encephalomyelitis caused by members of the lyssavirus genus. The disease may be caused by rabies virus genotype 1 (classical rabies) or less commonly by rabies-related lyssaviruses. The presentations are clinically indistinguishable. Rabies-related lyssaviruses implicated in human disease include European bat lyssaviruses (EBLVs) and Australian bat lyssavirus (ABLV).
• Rabies is a disease which affects humans and all mammals, including cats, dogs, wildlife, farm animals. The disease is absent from land mammals in the UK but has been detected at a low prevalence in certain species of bats in the UK. It is almost invariably fatal once signs of the disease have appeared. Infection is usually spread by the bite of an infected animal because the virus is present in saliva, but even licks from an infected animal may transmit the disease. The incubation period is most often one to three months however may be several months or even years, particularly if bites are distal and peripheral.
• Some species of bats may carry certain strains of the virus without developing disease themselves, but they can still to spread it to other animals.
• Vaccination is offered to people who are potentially exposed to Rabies. To obtain rabies vaccine and immunoglobulin post exposure contact Public Health England on 020 8200 4400. For further information, see HPA guidelines on managing rabies post-exposure prophylaxis.

Individuals who are at continuous risk should have their antibody levels tested every six months. Reinforcing doses of vaccine should be given if serology indicates that antibody levels are below a protective antibody titre of at least 0.5 IU/mL (WHO 2010).

• For those at frequent risk, a single reinforcing dose of vaccine should be given one year after the primary course has been completed. Further booster doses should then be given at three to five years.
• Post vaccination samples can be sent at any time.
• If a case of rabies is suspected, the Clinical Microbiologist must be contacted urgently BEFORE any samples are taken for analysis in Pathology. It is often not possible to confirm a suspected diagnosis of rabies by laboratory tests ante mortem; post mortem specimens are usually required to confirm the diagnosis.

Sample requirements

Serum - paired samples not required

8.5ml of blood taken into a plain gel tube

Required information

Suspected case/exposure

• Essential information include district and country visited including travel dates, type of animal exposure (which animal, lick or bite, site of exposure), and dates of exposure, current health of animal if known
• Vaccination history
• For a suspected symptomatic case give relevant clinical details, including symptoms and date of onset

Post vaccination

• Occupational hazard (e.g. UK bat handler)

Storage/transport

Store at fridge temperature

Transport as soon as possible at ambient temperature

Turnaround time

Sent to a National Reference Centre

Up to 21 days for post vaccination testing