VLA is the National Reference Laboratory for rabies in the UK and the Laboratory was re-designated as a Communicable Disease Surveillance and Response World Health Organisation (WHO) Collaborating Centre for the characterisation of rabies and rabies-related viruses in March 2003, and as such is engaged on:

Research - focussing on:

• improvements in diagnosis
• investigation of the pathogenesis of rabies and rabies-related viruses in terrestrial mammals
• investigation of the molecular epidemiology of rabies virus isolates collected from around the world
• investigation of epitope mapping and vaccine efficacy
• investigation of new therapeutic products for use in post-exposure treatment regimes

Surveillance
In the UK, bats found dead are submitted and tested at VLA under a programme of ‘passive surveillance’. This work is undertaken in close collaboration with the UK Bat Conservation Trust and between 1986 and 2002, only two out of 3,213 bats tested have been confirmed positive.

Microarray equipment detects the DNA make-up of cells

Pet Travel Scheme (PETS)
The scheme permits dogs and cats to enter the UK from EU member states and other specified countries without having to undergo quarantine, providing specific conditions are met. One of these conditions is for a blood sample to be tested by an approved laboratory for the presence of rabies neutralising antibodies. VLA has tested nearly 14,000 samples during the year.

Graph Number of samples received for the Pet Travel Scheme 1999-2003 Click here to open

Rabies in the UK
The UK is free from rabies with the last human death from indigenous rabies (RABV; classical rabies virus) recorded in 1902. Between 1977 and 2000, nine human rabies deaths occured from infections acquired overseas; two additional human cases in 2001 were imported from the Philippines and Nigeria.

Daubenton’s bat (Myotis daubentonii)

The first isolation of a lyssavirus from a bat in the UK was from a Daubenton’s bat (Myotis daubentonii) in Sussex in 1996. Daubenton’s bats are the third most common species in the UK with a population estimated at 150,000. The virus was subsequently characterised as a European bat lyssavirus (EBLV) type-2a.

Table Data One per cent agarose gel showing the second round RT-PCR for European bat lyssavirus type 2 nucleoprotein in organs from the Lancashire Daubenton’s bat. A summary of 1st- and 2nd-round PCR, with the results of virus isolation, is also shown. ND - Not Done. Click here to open

In September 2002, VLA reported a rabies-related virus in another Daubenton’s bat in Lancashire using conventional diagnostic tests on brain samples. Both the hemi-nested reverse transcriptase polymerase chain reaction (RT-PCR) test and ante-mortem saliva samples proved positive for rabies. A 400 base-pair region of the nucleoprotein gene was sequenced and confirmed the presence of an EBLV type-2a.

Map Data Western Europe showing the approximate location of European bat lyssavirus type 2 cases in bats and humans. Click here to open

In November 2002, VLA reported the first indigenously acquired case of EBLVtype-2a in a human from Scotland. A 55-year-old bat conservationist was admitted to Ninewells Hospital Dundee, Scotland with a rapidly progressive unexplained neurological illness.He presented with a five day history of pain and paraesthesia in the left arm followed by increasing weakness of his limbs with evidence of evolving encephalitis.

He admitted to numerous exposures throughout 2002 involving close handling of different species of bat and had been previously bitten by bats on some occasions while not wearing gloves. In September 2002, in Scotland, he was bitten on the ring finger of his left hand. The bat associated with this biting incident was considered to be a Daubenton’s bat. The bat, however, was not retained for analysis and subsequently no accurate information on the exact identification of the species of bat has been possible. The source of infection was almost certainly from the UK, as the victim had never handled bats outside of Scotland except when he last travelled abroad to Papua New Guinea during 1995/96.

On 24 November 2002, thirteen days after admission to hospital, the patient died. Post-mortem diagnostic tests including the fluorescent antibody test (FAT), RTCIT and RT-PCR on three brain samples (cerebellum, medulla and hippocampus) were positive. A mouse inoculation test was also performed. Clinical signs of a rabies-like illness developed in five inoculated mice between 13 and 17 days post-infection. Brain smears from each infected animal were positive by the FAT and viable virus was isolated.

This fatal incident is only the second confirmed case of an EBLV type-2a infection in a human following exposure to bats. The only previously recorded case of an EBLV type-2a in a human patient was reported from Finland in 1985.

In order to understand the true prevalence of EBLVs in British bats, an ‘active surveillance’ programme, jointly funded by Defra and the Biotechnology and Biological Sciences Research Council was initiated. Sampling of bats in Scotland, funded by Scottish Natural Heritage, began in March 2003 and future projects will be focussed in Lancashire and sampling at some swarming sites will be carried out in South West England.