State public health officials announce first EEE positive mosquito samples in southeastern Massachusetts

The Massachusetts Department of Public Health (DPH) today announced that eastern equine encephalitis (EEE) virus has been detected in Plymouth County for the first time this year. The presence of EEE was confirmed today by the Massachusetts State Public Health Laboratory in mosquito samples collected on July 13 from a single location in Carver in Plymouth County. The mosquito samples collected July 13 are from the same trap collected on the same night. The findings are in a mammal-biting species of mosquito.

Data from the area will be reviewed and the risk levels in the area will be updated tomorrow as part of routine bi-weekly risk level changes by DPH. Information about current mosquito activity will continue to be updated regularly and can be found here.

The findings mark the third time EEE virus has been confirmed in tested mosquito samples in Massachusetts this year. The two earlier findings of the virus were detected in samples collected July 1 and July 5 in Franklin County, increasing the risk level of EEE to moderate in the communities of Orange, Athol, Wendell and New Salem. No human or animal case of EEE has been detected so far this year.

EEE is a rare but serious and potentially fatal disease that can affect people of all ages. EEE is generally spread to humans through the bite of an infected mosquito. There were 12 human cases of EEE in Massachusetts in 2019 with six deaths. There were also nine cases in domestic animals. Last year, public health officials raised the risk level for EEE to high in several communities in Bristol and Plymouth counties, both historic hotspots for EEE activity.

West Nile virus has also been detected this year in mosquitoes in Middlesex and Suffolk counties. There were 5 human cases of WNV in 2019. No human or animal cases of WNV have been detected so far this year.

Avoid Mosquito Bites
Apply Insect Repellent when Outdoors. Use a repellent with an EPA-registered ingredient (DEET (N, N-diethyl-m-toluamide), permethrin, picaridin (KBR 3023), oil of lemon eucalyptus [p-methane 3, 8-diol (PMD)] or IR3535) according to the instructions on the product label. DEET products should not be used on infants under two months of age and should be used in concentrations of 30% or less on older children. Oil of lemon eucalyptus should not be used on children under three years of age.

Be Aware of Peak Mosquito Hours. The hours from dusk to dawn are peak biting times for many mosquitoes. Consider rescheduling outdoor activities that occur during evening or early morning in areas of high risk.

Clothing Can Help Reduce Mosquito Bites. Wearing long-sleeves, long pants and socks when outdoors will help keep mosquitoes away from your skin.

Mosquito-Proof Your Home
Drain Standing Water. Mosquitoes lay their eggs in standing water. Limit the number of places around your home for mosquitoes to breed by either draining or discarding items that hold water. Check rain gutters and drains. Empty any unused flowerpots and wading pools, and change the water in birdbaths frequently.

Install or Repair Screens. Keep mosquitoes outside by having tightly-fitting screens on all of your windows and doors.

Protect Your Animals
Animal owners should reduce potential mosquito breeding sites on their property by eliminating standing water from containers such as buckets, tires, and wading pools – especially after heavy rains. Water troughs provide excellent mosquito breeding habitats and should be flushed out at least once a week during the summer months to reduce mosquitoes near paddock areas. Horse owners should keep horses in indoor stalls at night to reduce their risk of exposure to mosquitoes. Owners should also speak with their veterinarian about mosquito repellents approved for use in animals and vaccinations to prevent WNV and EEE. If an animal is suspected of having WNV or EEE, owners are required to report to the Department of Agricultural Resources (DAR), Division of Animal Health by calling 617-626-1795 and to the Department of Public Health (DPH) by calling 617-983-6800.

More information, including all WNV and EEE positive results, can be found on the Arbovirus Surveillance Information webpage at www.mass.gov/mosquitoesandticks or by calling the DPH Division of Epidemiology at 617-983-6800. A short video with State Epidemiologist Dr. Catherine Brown about EEE and what residents can do to protect themselves can be found here.