After a temporary lull caused by summer dryness, mosquito populations in Maryland are on the rise, sparking renewed concern about mosquito-borne illnesses. The first mosquito-borne illness many people think of in this area is West Nile virus, which was detected in mosquitoes in the county this summer, but there are other illnesses of concern as well.

The Maryland Department of Agriculture (MDA) conducts mosquito surveys and traps mosquitos to monitor mosquito-borne illnesses. The mosquito surveillance traps collect adult female mosquitoes, which are then analyzed at a lab to determine the species and numbers. Based on the results of the trapping, the MDA may conduct extra spraying in a particular area. (Routine spraying is also a standard part of mosquito control efforts in the county; while residents may opt out of the routine sprays, they may not opt out of the extra sprayings.)

In the month of August, the MDA conducted 10 extra sprayings in areas of Prince George’s County, as opposed to seven extra sprayings in 2022 and six in 2021. Affected areas include Laurel, Riverdale Park, Greenbelt and unincorporated Hyattsville. Daniel Schamberger, a mosquito control administrator with the MDA, told the Life & Times that although mosquito-borne illnesses have been getting more attention recently, it’s pretty typical to see a small rise in mosquito numbers in the late summer and early fall, as increased rain provides the insects with more pooled water in which to breed.

West Nile virus is generally a mild illness, with a high percentage of infected people having no symptoms at all. Most who do show symptoms report a fever, body aches or a headache; only very rarely is the disease severe enough to require medical attention. The Maryland Department of Health has not reported any diagnosed cases of West Nile virus in the county this year, despite the fact that some mosquitoes caught in traps tested positive for the virus.

However, and more concerningly, in mid-August, a Maryland resident living in the National Capital Region, which includes Prince George’s County, tested positive for a locally acquired malaria infection. According to the Maryland Department of Health, the state sees about 200 cases of travel-related malaria per year, which occur when someone travels abroad, is infected with malaria in a different country, and then brings it back home. However, this is the first malaria case in Maryland that has been identified as not travel-related in over 40 years. Two other states, Florida and Texas, have also seen locally acquired malaria this year, according to the Centers for Disease Control and Prevention.

Malaria symptoms include high fever, chills, body aches, diarrhea and vomiting. Malaria can be very serious if not treated promptly.

A third mosquito-borne illness, the Zika virus, which can be spread by the Aedes mosquito or by unprotected sex with an infected person, remains without any known locally transmitted cases in Maryland, according to the Department of Health.

The Zika virus can be very dangerous for pregnant women, as it can cause serious birth defects in the developing child; however, it is generally a mild disease that doesn’t require hospitalization. Symptoms include fever, rash, joint pain and conjunctivitis (red and itchy eyes).

Schamberger said that, despite the positive malaria test, there is no reason for county residents to worry unduly. “In general, people should just be concerned overall about mosquito-borne disease,” he said. 

Schamberger recommended taking preventative measures against mosquitos, such as wearing long clothing or using mosquito repellents, as well as avoiding going outside when mosquitoes are most active (right at dark and in the early morning). 

Most importantly, Schamberger stressed the need for county residents to monitor their yards for containers of standing water and dump them out or clean them regularly to prevent mosquito larva from developing inside. “You can really help eliminate mosquito problems,” he said.

For more information on mosquito spraying or to report high mosquito numbers, visit