Hartford, Conn. x
A DNA analysis of blood taken from the abdomens of 300 mosquitoes trapped in Connecticut over the past three years found that 40 percent fed on the blood of the red-breasted songbird and only 1 percent on crows, said Theodore Andreadis, chief medical entomologist at the Connecticut Agricultural Experiment Station.
"It was quite surprising," he said. "Robins are right up there and are probably playing a pretty good role."
His findings have been turned over to the federal Centers for Disease Control and Prevention for publication in the agency journal Emerging Infectious Diseases.
A CDC expert on West Nile is skeptical. However, the results are similar to the studies of Charles Apperson, an entomologist at North Carolina State University. He also found robin blood, but little from crows, in mosquitoes he has tested over a four-year period in New York, New Jersey and Tennessee.
"We felt like we were expecting we would find that mosquitoes fed on crows. That didn't seem to be the case," Apperson said.
In most cases, humans infected by West Nile virus experience only mild, flu-like symptoms. But the virus also can trigger dangerous, and sometimes lethal, cases of meningitis and encephalitis.
Andreadis said the next step in research would be to catch robins in special mist nets and test their blood. The non-lethal tests would tell researchers if the birds are an effective reservoir for the disease. "It's got to be there in high levels for along period of time," Andreadis said.
But testing the theory may be tough. Robins - the state bird of Connecticut, Michigan and Wisconsin - are wily in avoiding the nets, researchers said.
West Nile virus has been identified in more than 200 species of birds, according to the CDC.
But Nick Komar, the CDC's lead bird West Nile researcher, is skeptical of the robin's newfound dubious distinction. It's too early to tell, he said.