Page last updated at 16:08 GMT, Tuesday, 7 October 2008 17:08 UK

Disease warning on climate change

By Richard Black
Environment correspondent, BBC News website, Barcelona

Digital image of a mosquito (Image: Science Photo Library)
Changes to the climate are enabling mosquitoes to move northwards

Climate change may hasten the spread of diseases that can move from wild animals to humans, warns the Wildlife Conservation Society (WCS) in a report.

The Deadly Dozen highlights 12 zoonoses - animal-borne diseases - that may spread as the climate warms.

The US-based organisation advocates establishing a global early warning network making use of Western and indigenous people's knowledge.

The report was launched here at the World Conservation Congress.

"We've seen Lyme disease work its way up from the US into Canada, and West Nile fever as well," said William Karesh, director of WCS's global health programmes.

"Basically what you have now are fewer frozen nights in this region, and that allows the ticks and mosquitoes that carry these diseases to survive further north."

In its landmark assessment of climate impacts, released last year, the Intergovernmental Panel on Climate Change (IPCC) noted that elevated temperatures would change the distribution of animals that carry diseases affecting humans, and that improved disease surveillance was a "climate adaptation" measure that some countries were already taking.

Long-term gains

Among the other zoonoses likely to be affected by climatic shifts are avian influenza, Rift Valley fever, and Ebola, the WCS report says.

Monitoring wildlife health will help us predict where trouble spots will occur and plan how to prepare
Steven Sanderson,
WCS chief executive

Prevalence of Vibrio cholerae, the bacterium that causes cholera, rises with water temperature, and can be incubated in shellfish.

Some shifts might not be triggered by rising temperatures. Water scarcity, for example, could induce more sharing of drinking pools by wild and domesticated animals, making the emergence of new viral strains more likely.

WCS acknowledges that climatic shifts could also lessen the prospects for some zoonotic diseases.

Without observations, it suggests, we cannot really know; and wild animals can act as early indicators of disease.

"The health of wild animals is closely linked to the ecosystems in which they live, and even minor disturbances can have far-reaching consequences on what diseases they might encounter and transmit as climate changes," said the organisation's chief executive Steven Sanderson.

"Monitoring wildlife health will help us predict where trouble spots will occur and plan how to prepare."

For some time, it has been urging the strengthening of monitoring systems at a national and global level so that early signs of outbreak are detected and dealt with.

It operates the Global Avian Influenza Network for Surveillance (Gains) project, which is funded by US government agencies.

But, said Dr Karesh, indigenous knowledge and skills should also be brought into play.

In northern Republic of Congo, he said, hunters used to bring dead animals they found in the forest back to the villages, which in the case of animals that had died from Ebola would immediately produce a human outbreak.

"Now the local people look out for these animals, they don't bring them back but report what they have found.

"So they are doing disease surveillance, and there hasn't been an outbreak of Ebola in this region for several years."




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