A dead crow found in downtown Baltimore this month was infected with the West Nile virus that caused the death of seven people in and around New York City this summer, Maryland health officials said last night.
The confirmation of the virus -- which is transmitted by mosquitoes and usually found in Africa -- was made yesterday by the national Centers for Disease Control and Prevention in Atlanta. The infected bird was found Oct. 14 in the 300 block of E. Lombard St.
The disease can be spread to humans only from the bite of an infected mosquito. Humans cannot get the virus from other humans or from birds. And mosquitoes stay infectious for a limited period, about four to five days.
Because the onset of cold weather has all but killed this year's mosquito population, the risk is considered low.
While urging Marylanders to take precautions against mosquitoes -- primarily staying inside during the insects' feeding times at dawn and dusk and using repellent -- local officials stressed that the danger to humans is minimal and asked residents not to panic.
"The people most vulnerable are the elderly, people with HIV or the AIDS virus, people with kidney transplants, cancer patients being treated with chemotherapy and others with [faltering] immune systems," said Dr. Georges C. Benjamin, Maryland secretary of health and mental hygiene.
Symptoms for the virus are nearly identical to viral encephalitis, an inflammation of the brain, and include fever, stiff neck, severe headaches, an onset of confusion and paralysis of the arm or leg.
Healthy people who are infected would most likely experience nothing more than flu-like symptoms, and might have no symptoms at all, officials said.
No vaccine for the virus exists. Physicians treat the symptoms with fluids and anti-fever agents. Anyone who has any of the symptoms should see a doctor immediately.
Since an epidemic of West Nile virus hit New York in August, causing more than 50 people to become ill in addition to the deaths, 34 birds from Maryland have been autopsied. Only the bird found Oct. 14 turned out to be infected. No infected mosquitoes have been found in Maryland, officials said.
Dr. Peter L. Beilenson, city health commissioner, said last night that he will notify local emergency departments for potential cases and survey hospitals for any patients who might come down with the virus. He said he plans to talk today with health officers for all the counties in the region.
He emphasized that the public needs to keep this finding in perspective.
"It's very unlikely there are mosquitoes around. It's even more unlikely that mosquitoes are carrying this because there's only been one bird found in the entire city, and we've been looking for dead birds for weeks," Beilenson said.
Health officials have been worried that birds infected with the virus -- crows and some other wild species -- might spread it as they migrate south. Since September, the CDC, the U.S. Geological Survey and health officials have been sampling live and dead birds in states along the Atlantic seaboard.
Neither West Nile fever nor Australia's Kunjin virus, which also is borne by mosquitoes and turned up in New York this summer, had been found before in North America.
Dead birds, especially crows, should be reported to the state at 1-888-584-3110.