Bat rabiesBMJ 2003; 326 doi: https://doi.org/10.1136/bmj.326.7392.726 (Published 05 April 2003) Cite this as: BMJ 2003;326:726
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This editorial examines the not fully understood epidemiology of bat-
rabies and rabies-like infection in the UK. Because of the impact of
opinions expressed in BMJ on its worldwide readership, a global village
perspective is deemed pertinent.
Will the known and potential hosts and reservoirs of bat lyssaviruses
[BLVs] in Britain (and indeed elsewhere) remain constant? The passive
surveillance in the UK, as referred to here, may not be adequate enough to
determine the current level of risks to BLVs as well as provide inertia
for evidence-based prevention protocols. One may cast a glance into
resource-limited countries with known endemicity of various BLVs.
An example is Nigeria, my home country, where the Lagos bat and
Mokola lyssaviruses (genotypes 2 and 3 respectively) were first isolated.
There is simply no known surveillance in the recent past to monitor BLVs
in their reservoirs, domestic animals or in clinical human disease.
However, previous work implicated the Mokola virus in rabies-like
mortalities canine mortalities within one year of antirabies vaccination
; detected antibodies to Mokola and Lagos viruses in unvaccinated dogs
and human subjects ; and had isolated the Mokola virus from a girl .
Why have we not seen mortalities well documented related to these viruses
in these areas, where, unlike in the UK, human contact with bats known to
harbour BLVs is very common. Bats are also eaten in some communities.
Obviously, surveillance is lacking. Institution of active surveillance in
isolated Islands like the UK may precipitate required similar measures in
endemic regions. This makes it unambiguous that the risk in UK or
elsewhere is not always linearly defined.
The possibilities for ecological changes in the UK and elsewhere to
favour BLV transmission in susceptible hosts/reservoirs have been recently
discussed . One example given notes the translocation of one known
Rabies virus [RABV] reservoir, Hoary Bats (Lasiurus cinereus), to the
Orkney Islands, off rabies-free Scotland. Wind assisted translocation of
virus harbouring bats from France, where bat rabies is a reality and
importation of African virus strains occur , and elsewhere in
continental Europe to the UK has been suggested. As a reminder, BLVs can
be found, not only in arboreal animals but also in domestic animals such
as cats and dogs . The possibility thus exist that, if not already, the
European BLVs can infect these companion animals. Again, surveillance
would be vital.
The at-risk subset of the rabies-naïve population that should be
immunized may thus include travelers to BLVs endemic (where potential
contact with such bats is high) regions as well as bat-infested caves.
There is a caveat here – will the current vaccines available be effective
against ALL known BLVs? Or just the ones current understanding assert to
be circulating in Europe? Potent anti-rabies vaccines have been found not
to protect against challenges with Lagos bat or Mokola virus . And
there is the Aravan BLV, for which scant information is available.
Isolated from the lesser Mouse-eared Bat (Myotis blythi), it does not
belong to any of the seven known Lyssavirus genotypes . The bat has a
wide geographical distribution. What challenges these pose to future BLV
prevention is unknown at this time.
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Competing interests: No competing interests