Health officials in Arlington are urging residents to take action to prevent mosquitos from breeding and spreading disease. The town’s health department is asking residents to drain standing water, check rain gutters, drains, empty flowerpots and wading pools, and to change the water in birdbaths frequently as mosquitos lay their eggs in standing water. Residents are also being encouraged to install or repair screens on windows and doors, and avoid being bitten by mosquitos by using insect repellant. Arlington has had mosquitoes that tested positive for West Nile virus in recent years, including last summer. The virus is most commonly transmitted to humans through bites by infected mosquitoes. Arlington treats storm-water catch basins to prevent mosquito breeding.