Spraying and surveillance are the Health Department's answers to the mosquito problem.
After two people acquired malaria in eastern Loudoun, the Health Department sprayed pesticide on Monday night to kill adult mosquitoes in the Cascades and Sugarland Run areas.
"It's important they are killed so no further people are infected by malaria," said David Goodfriend, Health Department director, about an infectious disease transmitted to humans through mosquito bites.
Spray trucks from Clarke Environmental Mosquito Control sprayed Anvil in a one-mile radius from the Sugarland Run Community Center, working from dusk to about 1 a.m. The spraying killed up to 98 percent of the adult mosquitoes, said John Neely, operations manager of Clarke.
"If you have malaria, it is usually in a focused area," Neely said.
"Different mosquitoes fly different lengths but the anopheles mosquito, the one we are concerned with, flies about a half mile or so," said Goodfriend. "That's why when we were looking at a radius for spraying we chose a mile," he said, "'adding that all the mosquitoes tested so far have tested negative.
A 15-year-old boy and a 19-year-old woman who are unrelated acquired malaria in the Cascades and Sugarland Run areas. The boy begin feeling ill on Aug. 12 and was hospitalized for a short time. The woman was treated on an out-patient basis when she first became ill on Aug. 20. Laboratory samples were sent to the state's Division of Consolidated Laboratory Services in Richmond for confirmation.
"Malaria is a very rare infection for people to contract inside the U.S.," Goodfriend said about the two cases, which involved residents who have not recently traveled outside the United States. "We do have the type of mosquito that can transmit malaria. But this is a rare occurrence to happen."
THE HEALTH DEPARTMENT will conduct a human surveillance of the Cascades and Sugarland Run areas to identify any malaria cases not diagnosed during the summer. The department will ask local emergency departments and urgent care centers if any patients had fevers.
"We're concerned about people who have been seen with a fever and not diagnosed with malaria," Goodfriend said.
Benita Boyer of Fairfax, who began Tuesday as the department's new epidemiologist and bioterror expert, will help with the surveillance work, giving her input on the steps to take and the best way to conduct the surveillance. A member of the Centers for Disease Control (CDC) arrived Sept. 6 and will remain this week to support the health department staff with the work.
About 1,200 cases of malaria are diagnosed in the United States each year, the majority involving immigrants and travelers returning from malaria risk areas. In Virginia, an average of 60 malaria cases are reported to the state Department of Health each year. The last time a Virginia resident was reported to have malaria without any history of international travel was in 1998 in the Tidewater area.
Symptoms of malaria include fever and the flu-like symptoms of shaking chills, headache, muscle aches and tiredness. Nausea, vomiting and diarrhea can also occur. Symptoms typically appear one to two weeks after a person is bitten by an infected mosquito.