The official start date of the 2021 Arbovirus Surveillance Season this year began on Monday, June 14, 2021. The State Public Health Laboratory will begin mosquito testing. June through October is typically mosquito testing season in the New England area. This year the surveillance is gearing up to hlep assess the risks of Arbovirus this summer.
Arbovirus is the term used to refer to diseases transmitted to through the bite of an infected arthropods; mosquitos, ticks, fleas and gnats. Arbovirus diseases you may have heard of are Triple E (Eastern Equine Encephalitis) or West Nile Virus; spread through the bite of an infected mosquito. Another Arbovirus in the News is Lyme disease spread through the bite of an infected black legged tick.
The Department of Public Health (DPH) works with Mosquito Control Districts (MCD) to conduct surveillance of mosquitos and specimens from both human and animals to monitor disease and risks. This surveillance provides information for the public on mosquito control and risk of infection. The following chart provides a summary of the 2020 Arbovirus result:
| MOSQUITO POSITIVE SAMPLE | ANIMAL POSITIVE | HUMAN POSITIVE | |
| WNE | 97 | 0 | 8 |
| EEE | 66 | 0 | 5 |
The Massachusetts Department of Public Health(MDPH) also conducts surveillance of tick exposure and Tick-borne Disease by collecting information on patient visits to hospital emergency departments for tick exposures. The information collected focuses on two types of emergency department (ED) visits: tick exposures – where an individual presents to the ER with a report of an exposure to a tick, and tick-borne disease – where an individual is given a diagnosis of a tick-borne disease. This information is presented in the following graphs collected for 2020 (Figure 1) and so far for 2021 (Figure 2).
FIGURE 1: The graphs below show that in December of 2020, less than 0.2% of visits to EDs in any week were related to exposure to ticks, while less than 0.1% of visits to EDs in any week were related to diagnosis of a tick-borne disease. The 2020 data are shown compared to both the minimum and the maximum number of visits recorded over the last three years. Tick activity usually increases sometime in March or April depending on weather.
FIGURE 2: The graphs below show that in April of 2021, less than 0.5% of visits to EDs in any week were related to exposure to ticks, while less than 0.1% of visits to EDs in a week were related to diagnosis of a tick-borne disease. The 2021 data are shown compared to both the minimum and the maximum number of visits recorded over the last three years. Tick activity usually increases sometime in March or April depending on weather.
Also of interest is the historical data of confirmed Lyme disease cases by month of disease onset, in the United States from 2008-2019. The is information from the CDC.
