The virus that killed and sickened people and wildlife in the New York area in late summer has been discovered in the carcass of a crow that was found near Baltimore's Inner Harbor, Maryland health officials said yesterday.

It is believed to be the first time since the illness, the so-called West Nile virus, was detected in August that it has been found outside the greater New York City area. Scientists said they had feared the virus might spread with the fall bird migrations.

The disease is treatable in most people who contract it. But it is believed to have killed about a half-dozen elderly people in the New York City area and sickened about 40 others. It has also killed numerous fowl, especially crows, and was detected recently in horses on Long Island.

The virus is contracted through mosquito bites. It causes encephalitis, a swelling of the brain, and can attack birds, humans and other animals.

"The weather is in our favor," Michael Morrill, a spokesman for Gov. Parris N. Glendening (D), said last night. "Cold weather eliminates the mosquito problem for the winter."

Since the New York outbreak, physicians, wildlife managers and mosquito control officials have been testing for traces of the virus along the East Coast.

The infected bird was discovered Oct. 14 in Baltimore. It was one of 34 dead crows found in the city and in Montgomery, Anne Arundel, Howard and other counties that were shipped to a government screening laboratory in Madison, Wis., to be tested for the virus.

In addition, blood from 32 ducks killed by hunters in Dorchester County has been sent there for testing. Officials said the virus has been found only in the crow from Baltimore.

State officials stressed last night that no virus has been found in people, though they said they would review any cases of encephalitis that have been reported in recent months. The illness can be caused by many other factors.

Experts already had partially reviewed one encephalitis case, that of a child in Shelltown, Somerset County. The child, who survived, has not been tested for the West Nile virus.

Georges C. Benjamin, the state's secretary of health and mental hygiene, said last night that the dead crow was found about two weeks ago in the 300 block of Lombard Street, about a block from the Inner Harbor.

That bird and the others were shipped to the U.S. Geological Survey's National Wildlife Health Center in Madison.

Screening there showed traces of illness, and more refined testing conducted by the Centers for Disease Control and Prevention revealed the presence of the virus, officials said.

Birds also were sent for testing from several counties in Virginia.

The Virginia state epidemiologist, Suzanne Jenkins, said three crow carcasses had been sent in recent weeks. Two of the carcasses had been recovered from the Northern Neck region of the state and the other from around Virginia Beach, she said.

Paul G. Slota, a biologist at the Madison laboratory, said the tests have not yet revealed whether any of the dead crows from Virginia had the West Nile-like virus.

Glendening and other officials urged residents to be on the lookout and report crows or other birds that appeared to have died for no reason. State officials have set up a hot line at 1-888-584-3110. They also urged people to avoid mosquitoes, which even though the weather is cooler can be active on warm days, and to see a physician if they experience fever, neck stiffness or mental confusion--the symptoms of encephalitis.

Barbara Reynolds, a spokeswoman for the CDC, said the virus was found in the Baltimore crow at the CDC's testing facility in Fort Collins, Colo., where much of the work on the virus has been conducted.

She said wildlife--dead and alive--from New England to Florida was being tested for the virus. "We know the outbreak's waning, but we do want to get a sense of the scope of the outbreak," she said. "This is a pretty broad investigation."

Experts have said they do not know whether the virus might survive in wildlife or mosquitoes over the winter to return next spring.

The virus is spread mostly by the Culex pipiens mosquito, which weighs about 1 milligram, is active at dawn and dusk, and whose numbers are being rapidly reduced by the chilly mornings and evenings.

State mosquito control officials began capturing thousands of Culex pipiens several weeks ago in Baltimore and in Prince George's County and refrigerating them so they can be tested later for the virus.

Reynolds, of the CDC, said: "Because control measures have been put in place, and it is getting cooler, there's probably a very low risk of infection.

"But we're waiting for that big, hard freeze before we tell people they don't have to worry about going out," she said.

Staff writer Graeme Zielinski contributed to this report.