1 National Institute for Public Health and the Environment
(RIVM), Bilthoven, The Netherlands.
2 Central Institute for Animal Disease Control (CIDC) Lelystad, The Netherlands.
3Naturalis Museum, Leiden, The Netherlands.
The European bat lyssaviruses (EBLVs) are not easily transmitted
from bats to other species, but such incidents have occurred rarely. In humans
EBLV infection can be fatal, and to date, worldwide, four such cases have
been reported (1). The most recent was in November 2002, when a 56 year old
bat worker in Scotland died of an EBLV2 infection, about six months after
he had been bitten by a Daubenton's bat (Myotis daubentonii
) (2). Other
cases were a 15 year old girl in Ukraine in 1977, who died five weeks after
she had been bitten on her finger by a bat. In Russia in 1985 an 11 year old
girl died four weeks after a bat bite on her lower lip. Both girls were infected
with EBLV1. In the same year as the Russian case, a 30 year old bat researcher
in Finland died of rabies caused by EBLV2 (3). In both this case and the Scottish
case, it has not been definitely determined when the fatal bites took place.
In North as well as South America, human rabies due to bat bites is observed
more frequently, but in these continents this is always the result of a
classical rabies virus infection and the vampire bat (Desmodus rotundus)
is the main reservoir of this virus (4,5). The vampire bat is found from
Chile in South America to as far north as the southern United States, but
is not indigenous to Europe.
Rabies virus is a bullet shaped RNA virus, family Rhabdoviridae,
genus lyssavirus. This genus can be divided into seven genotypes:
Type 1, classical rabies virus (RABV); type 2, lagos bat virus; type 3,
Mokola virus; type 4, Duvenhage virus; type 5, European bat lyssavirus 1
(EBLV1); type 6, European bat lyssavirus 2 (EBLV2); and type 7, Australian
Bat Lyssavirus (ABLV). In north west Europe, genotypes 5 and 6 are of major
importance because these can be transmitted by bats. Classical rabies virus
has been eradicated from most of the countries of this region, but is still
endemic in wildlife in eastern Europe. This means that there continues to
be a risk of (re)introduction. There have been several such reintroductions
in the last few decades. The European bat lyssaviruses are endemic in free
living insectivorous bats in Europe (6). In the Netherlands, the serotine
bat (Eptesicus serotinus) is the main reservoir of EBLV1 and the
Pond bat (Myotis dascycneme) is the main reservoir of EBLV2. The
serotine bat is seen in all the countries of Europe except Ireland, Norway,
Iceland, Finland, and the northern parts of Great Britain and Sweden. The
Pond bat is also a native species in North West Europe. Highest concentrations
are reported from the Netherlands and the Baltic States, but it is assumed
that this bat also lives in large parts of eastern Europe.
In almost all cases bat lyssaviruses are transmitted after a percutaneous
wound, most often caused by a bite. Transmission of lyssavirus through aerosols
via mucous membranes has been described (7) but not for EBLVs. No one should
handle diseased or dead bats without protection such as gloves. People who
work with bats should be immunised. In the Netherlands bats involved in
biting incidents - if they can be captured - are tested for lyssavirus by
fluorescent antibody tests (FAT) on brain smears (8) at the Central Institute
for Animal Disease Control (CIDC) in Lelystad. People bitten by a lyssavirus
infected bat, receive post exposure prophylaxis. In unvaccinated persons
this consists of an immediate injection with antirabies immunoglobulins
(20 IE / kg) and 5 injections (day 0,3,7,14, and 28) with commercially available
rabies vaccine based on inactivated classical rabies virus (9).
From 1999 to 2001, a total of 280 bats were tested for lyssavirus at CIDC,
and 16 were found to be infected with EBLV1. All positive results were in
serotine bats. The prevalence of lyssavirus in serotine bats in the Netherlands
in this period was found to be 20% (16/82). Virus prevalence in the healthy
free living population is probably lower than in the bats submitted routinely
for testing. The National Institute for Public Health and the Environment
and CIDC Lelystad are working in a cooperative project to gain more insight
in EBLV prevalence in bats in the Netherlands. Sequence analyses of the
nucleoprotein encoding region of reverse transcriptase polymerase chain
reaction (RT PCR) amplified products of EBLVs detected in Dutch bats between
1997 and 2002 resulted in a 96-100% homology with EBLVs isolated in Europe
the last 10 years. EBLV2 sequences have not been detected in bats in the
Netherlands since 1993.
The United Kingdom (UK) remains rabies free. However, following the recent
death of a bat handler from EBL2 infection acquired in Scotland, the UK
has changed its policy and recommends pre-exposure vaccination of all bat
handlers as well as postexposure vaccination of anyone who is bitten or
comes into other close contact with bats in the UK (10). An agreed document
detailing answers to frequently asked questions is now available through
the website of the Department for the Environment and Rural Affairs (http://www.defra.gov.uk/animalh/diseases/notifiable/disease/bat_faq.PDF).
This may be useful for anyone dealing with queries about bat bites and other
bat exposures in the UK.