West Nile testing in DC

DC health officials announce positive West Nile samples in mosquitoes as citywide surveillance expands through October 31.

West Nile detected in DC mosquitoes across a ward

WASHINGTON — DC officials announced positive West Nile samples found in mosquitoes in Connecticut Heights. The DC Department of Health's Division of Animal Services said crews collected mosquito samples that tested positive for West Nile Virus. The department plans to survey neighborhoods across DC's eight wards through Oct. 31 as part of the summer mosquito control program. To curb the spread, workers will apply larvicide in catch basins and other standing water to target mosquito breeding at the source.

Traces of West Nile have appeared in the region this summer. In Hyattsville, Maryland, authorities sprayed permethrin-based insecticide in several neighborhoods. The DC program emphasizes source control by treating standing water, rather than relying solely on adult mosquito spraying. The CDC notes that West Nile can reach humans within two weeks of a bite; most infections are mild or asymptomatic, and a small share become serious. As of Thursday, the CDC had not confirmed any West Nile cases in humans in DC or Maryland for 2025, while 140 US cases have been reported nationwide, 82 of them neuroinvasive.

The city leans into a hands on approach, focusing on larval control in catch basins rather than broad spraying. That signals a preference for preventive measures that reduce breeding grounds before adult mosquitoes emerge. Communication to residents is steady but technical, which helps avoid alarm while keeping people informed. The larger trend is a regional patchwork of surveillance and response that reflects how climate and urban infrastructure shape vector-borne disease risk. Public health work like this depends on both data and public cooperation, from drain any standing water habits to timely repellent use.

Highlights

Vigilant health work helps communities stay ahead of the season