Mosquitoes in the U.S. can be infected with Chikungunya virus from Asia

New research from SRI International finds that mosquitoes commonly found in the United States can be infected with a disease-causing virus from Asia. The research findings are from a recent study that modeled how mosquito-borne infections can become introduced.  Study findings are published in the August 2012 issue of the journal Vector-Borne and Zoonotic Diseases.

In laboratory experiments, researchers demonstrated that mosquitoes from Virginia and Georgia can transmit a virus called Chikungunya (CHIKV), which has infected more than 2 million people in Asia, Africa, and parts of Europe since 2005. The U.S. has never witnessed an outbreak of CHIKV, although a number of infected people have been identified with a CHIKV infection acquired from travel to Asia.

Although CHIKV infection is rarely fatal, patients may suffer persistent complications, such as debilitating arthritis that can last from months to years. Currently, there is no drug to treat CHIKV and no vaccine is available.

"The findings underscore the importance of control measures, such as eliminating mosquito breeding sites, to prevent mosquito-borne viral infections for which there are no cures," said Rajeev Vaidyanathan, Ph.D., associate director of Vector Biology and Zoonotic Diseases in the Biosciences Division of SRI and lead study author.  "We are the first group to look at multiple field populations of mosquitoes with a recent epidemic strain of Chikungunya virus. This is relevant because the populations we sampled are what you would find in the real world."

SRI researchers worked with populations of the Asian tiger mosquito from the southeastern U.S. The tiger mosquito is common in Texas and the Midwest and along the East Coast as far north as New Jersey. Researchers raised mosquito larvae collected from outdoor sites in five counties in Virginia and one in Georgia, until the larvae became adult mosquitoes, and then fed females a "blood meal" with CHIKV. This viral strain is nearly identical to viral strains from India that have infected people arriving in the U.S. with a CHIKV infection.

Vaidyanathan also identified demographic factors that could contribute to a potential transmission of mosquito-borne infections.  Densely populated areas and areas close to major airports would be vulnerable to CHIKV transmission. Another important factor to consider is the number of home foreclosures in an area, because such homes often fall into disrepair and may include flooded basements, clogged rain gutters, and yards full of trash, all which can provide pools of stagnant water ideal for Asian tiger mosquitoes.