Mosquitoes found in Anne Arundel County tested positive for West Nile virus this week, marking the first sign of the disease in Maryland in 2010.

Officials confirmed the presence of the virus in the mosquitoes on Monday, the state’s Department of Agriculture announced Thursday.

Workers collected the mosquito sample on July 13 from a mosquito pool in the Linthicum area. Mosquito control personnel have since sprayed the area to kill infected mosquitoes.

“We know that West Nile virus may be present throughout Maryland. It typically appears at this time in the summer, so we are not surprised with this positive finding,” Secretary of Agriculture Buddy Hance said.

Alexandria, Va. reported infected mosquitoes on July 16.

Although West Nile can cause serious illness in humans, most people bitten by a mosquito carrying the virus don’t develop any symptoms.