The Massachusetts Department of Public Health reports that the 2021 arbovirus season will officially start on Monday, June 14, which is when mosquito testing will begin at the State Public Health Laboratory.

The 2021 Arbovirus Surveillance and Response Plan is available online. The 2020 Surveillance Summary can be accessed through the same page.

The web page includes resources for local boards of health to use in communicating with their communities.

The DPH anticipates that this will be the third year of an Eastern equine encephalitis outbreak cycle. The department reports that it is possible — but by no means certain — that the drought from last fall, which extended into this spring, may reduce EEE activity.

The DPH and the Department of Agricultural Resources will be conducting outreach to various stakeholders and will be providing updates.

Surveillance for mosquito-borne diseases (often called arboviruses) that can be spread by mosquitoes in Massachusetts provides important information about when and where people could be at risk. Routine mosquito testing is typically reported June through October. The DPH reports that it is conducting early season surveillance activities to assess the risk of West Nile virus and Eastern equine encephalitis.

EEE is a rare but serious disease caused by a virus that is generally spread to humans through the bite of a mosquito infected with the virus. EEE can cause severe illness and possibly lead to death in any age group; however, people under age 15 are at particular risk. EEE does not occur every year, but based on mosquito sampling, a high risk of occurrence of human cases currently exists.

West Nile virus is a mosquito-carried virus that can cause illness ranging from a mild fever to more serious disease like encephalitis or meningitis. It was first identified in the United States in 1999.