Birds buffer against virus

"18-02-2009

North American scientists studying West Nile virus have shown that more diverse
bird populations can help to buffer people against infection. Since the virus
first spread to North America it has reached epidemic proportions and claimed
over 1,100 human lives. “This is an important example of the links between
biodiversity and human health”, commented Dr Stuart Butchart, BirdLife's
Global Research and Indicators Coordinator.


Biodiversity is increasingly being recognised as socially and economically
important because of the valuable services it provides. The authors of this
latest research - John Swaddle and Stavros Calos - highlighted the
“increasing evidence for economically valuable ecosystem services provided by
biodiversity”. "

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"Scientists studying the virus looked at US counties east of the Mississippi River and compared their avian diversity with the number of human cases. They found that high bird diversity was linked with low incidence of the virus in humans. They reported that about half of the human incidences of West Nile virus could be explained by the differences in local bird populations. The study’s results also suggest that bird communities lowered human case numbers even when the epidemic was underway.

The way in which biodiversity and disease rates are linked has been dubbed the ‘dilution effect’. Although the exact mechanisms aren’t currently clear, scientists believe that increased diversity within an ecosystem reduces - or dilutes - the proportion of suitable hosts for a disease, and therefore reduces transmission rates. It has previously been studied through another infection, Lyme disease, but this new research suggests that it may be more widely applicable. If so, it could be a valuable tool for public health and safety plans" Read the full article. SeEtta