Robins spread West Nile
Robins spread West Nile
Robins spread West Nile
Mosquitoes love taste of state bird
By Robert Miller
THE NEWS-TIMES
The American robin's song is infectious. So is its blood.
A group of researchers has found that the robin ? Connecticut's state bird ? may be the prime host of West Nile virus, at least in the Northeast. They get it from mosquito bites.
"At some sites we tested, it was the major host," Peter Daszak, executive director of the Consortium for Conservation Medicine at the Wildlife Trust in New York, said Friday. "In some sites it was the almost the only host."
The researchers ? who have published their findings in the Proceedings of the Royal Society B: Biological Sciences ? also found that once the robins leave the scene and migrate south, mosquitoes spread the virus to a new favorite ? humans.
"After robins, it's people," Daszak said.
The findings involved researchers from the consortium, from the New York State Department of Health's Wadsworth Center in Slingersland, N.Y., and from the Smithsonian Migratory Bird Center at the National Zoo in Washington, D.C.
They confirm the findings of Theodore Andreadis, an entomologist with the Connecticut Agricultural Experiment Station in New Haven, who said last year that robins might be the main culprit for carrying West Nile in the state.
"It's important," the experiment station's director, Louis Magnarelli, said Friday. "In any scientific work, after you publish your findings, it's important that another lab confirm your work independently."
The New York team did its work by capturing mosquitoes that had recently fed at a series of sites in Washington, D.C., and Maryland. They were able to use DNA analysis to learn where the mosquitoes had their last meal.
They found the mosquitoes fed on robins 40 percent of the time, even though the red-breasted birds made up only 4 percent of the bird community. They also found robins had a high level of West Nile virus in their blood.
"We don't know why the mosquitoes favored robins," Daszak said. "Perhaps it's the red breast. Perhaps they have a certain scent."
Daszak said the sequence of mosquito preference ? first robins with lots of West Nile in their blood, then humans ? makes sense. Mosquitoes don't start spreading West Nile to humans until late summer or early fall ? when the birds begin to migrate south.
"It really starts to explain things," he said.
Daszak also said the group discovered that West Nile is an urban and suburban disease ? a pattern duplicated in Connecticut, where West Nile is most prevalent in the cities of lower Fairfield and New Haven counties.
"We found a lot of activity in Washington, D.C.," Daszak said. "But in some really nice forests in Maryland, we didn't."
The findings also showed, once and for all, that crows aren't the winged reservoir of the virus that researchers first thought.
Generally, the West Nile virus season starts with people finding dead crows in their yard ? crows killed by the virus. But this just shows crows are susceptible to West Nile. Robins aren't.
"The parasite never kills its host," said Milan Bull, senior director of science and conservation for the Connecticut Audubon Society.
Bull said robins are members of the thrush family.
"I wouldn't be surprised if other thrushes will be carrying West Nile," he said. "Wood thrushes, hermit thrushes, maybe even bluebirds. It's just robins are much more common."
West Nile virus was new to the U.S. in 1999, when it turned up in New York, New Jersey and Connecticut. It quickly spread up and down the East Coast, then west, across the country. It's now the most common mosquitoes-borne virus in the U.S.
In 2005, there were 3,000 West Nile cases in the U.S. and 119 deaths. Connecticut saw six cases and one death.
For most people who become infected, the disease includes flu-like symptoms ? headache, aching bones and muscles, fever ? that passes in a week or so. For a few people, primarily the elderly, West Nile infection can cause polio-like paralysis, chronic fatigue, and encephalitis.
For that reason, health officials now warn the public every year to remove any standing water in their yard where mosquitoes might breed. They also suggest people wear long-sleeved shirts and pants if outside at dawn and dusk when mosquitoes are most active, and to use mosquito repellent ? especially repellent with DEET.
Magnarelli said the experiment station has set up 91 mosquito traps in the state and is monitoring the insects' activity. Because May was so wet, there will be many patches of standing water for mosquitoes to breed in, he said.
"We're looking for a lot of things ? there's a whole list," Magnarelli said. "Last year, we found the LaCrosse virus in Fairfield. It's a Midwestern virus. This was the first time anyone found it in New England."
Bull of the Connecticut Audubon Society said the new findings should not leave people eyeing robin red-breast through the eyepiece of a hunting scope.
"It's not their fault," he said. "They're still wonderful birds. They're good insect eaters, they're good singers, they're the harbinger of spring. Life would be very dismal without robins around."
