To prevent mosquito eggs from hatching, health officials toss doughnut-shaped mosquito dunks into the water, where they dissolve, Bucher said. The dunks do not affect the adult mosquito population.
Developers and landowners are being told to treat their storm water management ponds, she said.
Home improvement and hardware stores will stock the dunks, which sell for about $6 for four dunks, Bucher said.
Maryland Department of the Environment and Department of Health and Mental Hygiene officials debated whether storm water management ponds should be treated, County Health Officer William Christoffel said in an interview before the meeting.
Environmental officials are concerned about the ponds' ecosystems, but health officials said concern for citizens' health was greater, Christoffel said.
Health officials will increase efforts to educate the public about West Nile and improve surveillance of stagnant water, Bucher said.
Four mosquito pools were tested in the county and all were negative, she said.
Most of the birds that have tested positive for West Nile virus in the county have been along the Smithsburg-Boonsboro corridor, but the problem appears to be moving west, Bucher said.
Of the 33 birds that have tested positive for West Nile virus since May, 27 have been in the area of the Smithsburg-Boonsboro corridor, according to a health department handout.
The birds' species include crows, blue jays, grackles, doves, sparrows, robins, a cardinal, a pigeon and a great horned owl that was found along Rench Road, Bucher said.
Seven people have been tested for West Nile virus in Washington County, including one person who lives in Frederick County and tested positive, Christoffel said.
Another person is a probable positive, but is awaiting confirmation, Bucher said. Health officials may still be waiting for test results on some of the other five people, she said.