Researchers have produced the strongest evidence yet to suggest that a
targeted reactive vaccination programme, rather than blanket
vaccination, can control infectious diseases like rabies in threatened
wild canid populations (wild dogs, wolves and foxes. (Low-coverage
vaccination strategies for the conservation of endangered species',
D.T.Haydon et al Nature 443, 692-695 -12 October 2006)

The research team from Oxford University, Edinburgh University and
Glasgow University demonstrated that by vaccinating just thirty per cent
of the Ethiopian wolf population, the spread of rabies during an
outbreak can be reduced.. Their study, published in the journal Nature,
suggests that by vaccinating wolf packs living in the connecting
mountain valleys close to the outbreak, they can contain disease
outbreaks with unexpectedly low overall levels of vaccine coverage.

For nearly twenty years Oxford University's Wildlife Conservation
Research Unit (WildCRU) have been studying these animals and in 1995
established the Ethiopian Wolf Conservation Programme (EWCP) to address
the most urgent threats to wolf survival. The population of just 500 can
only be found in remote mountain enclaves in the Ethiopian Highlands.
There are six subpopulations of between 10 and 50, with the largest
group of 350 living in the Bale Mountains in the southeast. Canid
diseases, such as rabies and distemper, are the major killers with
domestic dogs being the main disease-carriers. The EWCP continues to
vaccinate domestic dogs in wolf habitat in an attempt to protect the
wolves.

After rabies outbreaks in the Bale Mountains in the early 1990s, which
wiped out two thirds of the Ethiopian wolf population in this area, an
emergency vaccination programme was introduced in 2003 in response to
yet another outbreak that year.
The study, an analysis and modelling of data collected by the EWCP,
suggests that a preventative strategy to capture and vaccinate the whole
population is impractical as the wolves live in remote, inaccessible
mountain enclaves. The alternative strategy adopted by the EWCP is an
effective reactive response to outbreaks, whereby Ethiopian wolves
living in the mountain valleys close to infected packs are targeted. The
researchers have shown through modelling that even if outbreaks became
more frequent, fewer wolves would need to be vaccinated under this
targeted scenario, than under a wholesale vaccination programme, in
order to virtually eliminate the extinction threat posed by such
outbreaks.

The researchers suggest that routine monitoring of the population
enables the early detection of disease and a rapid response to deal with
it. In the event of a single suspected case, they suggest that
monitoring should be intensified and once two rabid carcass are found,
vaccination teams should be dispatched to target subpopulations living
in connecting valleys. Additional measures, such as vaccinating between
10 and 40 per cent of wolves in affected packs, if targeting the
particularly large and highly connected packs, can further reduce
overall mortality due to these outbreaks.

Dr Claudio Sillero-Zubiri, from Oxford's WildCRU, said: 'Ethiopian
wolves are on of the rarest carnivores in the world, restricted to a few
montane enclaves in the Ethiopian Highlands. Canid diseases, such as
rabies and distemper, transmitted from domestic dogs pose the most
immediate threat to their persistence, and targeted reactive vaccination
intervention presents a useful tool to protect the remaining small wolf
populations from extinction.'

Lead author Dr Dan Haydon, from the University of Glasgow, said:
'Theoreticians have devoted a lot of effort to working out how to
vaccinate populations in ways that prevent epidemics getting started,
but this requires coverage that is impractical in wild populations.

We've looked at vaccination studies that don't prevent all outbreaks,
but do reduce the chances of really big outbreaks - ones that could push
an endangered population over the extinction threshold. These strategies
turn out to be effective and a lot more practical.'

Dr Karen Laurenson, the University of Edinburgh, who has led the disease
work Ethiopian wolves said: 'We have shown that the vaccination of
Ethiopian wolves, when appropriately and strategically used, is a safe,
direct and effective method of reducing extinction threats. With the
advent of new generations of oral vaccines, such methods are becoming
ever more feasible and cost-effective.'

Professor David Macdonald, Director of the WildCRU, said 'The WildCRU's
aim is to put innovative science to practical use. These discoveries
would have been impossible without long-term field-studies, and they
show how cutting-edge science can have down-to-earth practical
significance both for the protection of a very rare, and spectacular,
wild species, and also for human well-being.'