Climate Change Boosts West Nile epidemic

Is Climate Change To Blame For This Year’s West Nile Outbreak?

Heat waves and drought supercharge West Nile.

Currently there are no vaccines or antivirals with which to prevent and control West Nile virus in humans.

Higher temperatures bolster the chances of infection on many fronts. Temperature has a profound effect starting at the source: the mosquito. Studies have found that mosquitos pick up the virus more readily in higher temperatures. Higher temperatures also increase the likelihood of transmission, so the hotter it is outside, the more likely a mosquito that bites an infected bird will carry the virus and the more likely it will pass it along to an unwitting human host.

In the United States, epicenters of transmission have been linked closely to above-averag.... In particular, the strain of West Nile in the US spreads better during heat waves, and the spread of West Nile westward was correlated with unseasonable w.... High temperatures are also to blame for the virus jumping from one species of mosquito to a much more urban..., leading to outbreaks across the US.

Though you might think that the droughts associated with heat waves would slow down mosquitos, it turns out to be the exact opposite. That’s because the main mosquito now involved in West Nile transmission, city-loving Culex pipiens, actually thrives in drought conditions. C. pipiens tends to breed underground in water that sits in city drains. During a drought, these pools become rich in organic material that C. pipiens needs to survive, whereas rainfall flushes the drains and dilutes the nutrients in the standing pools. Drought also has a negative effect on C. pipiens’ predators like frogs and dragonflies – and where there are less predators, there are more mosquitos. To add to the problem, drought tends to cause birds to cluster around water resources, making them easy pickings for hungry mosquitos and upping transmission rates.