Many more people probably were infected with the virus without knowing it because most people have no symptoms or signs of illness, Bucher said.
Less than 1 percent of those who contract the virus suffer even a very mild infection, health officials said. Fewer still suffer any more serious effects, they said.
Last fall the state and federal government's efforts to track the health problem included picking up and testing dead birds.
That won't be done this year because the virus is known to be present throughout the county, she said.
"We know it is here and here to stay," Bucher said.
Instead the state is leaving traps at mosquito breeding grounds to try to track how many of the mosquitoes have the virus, she said.
Mosquitoes have been trapped and tested in past years for other viruses but now they also will be tested for West Nile, Bucher said.
There are communities in the county that will be sprayed to kill both mosquito larva and adults. Communities wishing to have the spraying done can contact the Maryland Department of Agriculture, Mosquito Control Section, at 1-800-638-2209, Bucher said.
The disease first was recognized in the United States in 1999 in New York City, according to the Centers For Disease Control and Prevention's Web site at www.cdc.gov/westnile.
Last year, the CDC counted more than 4,000 cases of the illness in 40 states.
Of those, 277 people died, including seven each in Maryland and Pennsylvania and three in West Virginia.
Precautions and other information can be found on the Health Department's Web site at washhealth.org/news/wnvfact2.htm.