Climate change: weather linked to increased West Nile virus cases

Climate scientists have all along warned that increasing global temperatures caused due to the current phase of climatic change can lead to increased incidence of infectious disease. A study by a group of American scientists has added to the scientific evidence for this.

The objective of the study was “to identify meteorological conditions associated with reported human West Nile Virus cases in the United States.” The scientists assessed 16, 298 human West Nile Virus cases that were reported to the Centre for Disease Control in the period 2001 to 2005.

Their study found that “warmer temperatures, elevated humidity, and heavy precipitation increased the rate of human West Nile Virus infection in the United States independent of season and each others’ effects.”

The West Nile Virus belongs to the genus Flavivirus, the same as the viruses that causes Dengue Fever, Yellow Fever and Japanese Encephalitis. The virus spreads through insect bites, mainly mosquito bites, and causes symptoms like fever, chills, headache, joint pains in infected individuals, and may also cause encephalitis.

Moquito populations generally increase with increasing temperatures and decrease with decreasing temperatures. Climate scientists fear that an increase in average temperatures due to global warming may increase populations of mosquitoes and other disease carrying insects, and may lead to greater incidence of infectious disease.

The study titled “How Weather Influenced West Nile Virus in the United States, 2001-2005”, done by Jonathan E. Soverow, Gregory A. Wellenius, David N. Fisman, and Murray A. Mittleman, was published in Environmental Health Perspectives.