When mosquito and tick season hits COVID-19


With the COVID-19 restrictions being relaxed, people are spending more time in socially distant outdoor gatherings, whether it’s picnics in parks with friends or movie nights in the backyard with neighbors. But if we escape the lines of COVID-19 quarantines, we will go outside into high mosquito and tick season.

Have you stocked up on bug spray yet?

Think back to the fall of 2019 when Massachusetts faced another type of public health threat: an unusually active year for mosquitoes with the deadly eastern equine encephalitis (EEE) virus. Electrical and electronic equipment symptoms are similar to the flu, such as fever, chills, headaches, and body aches. However, the disease can lead to encephalitis – an inflammation of the brain that can lead to coma, convulsions, or death. There is no treatment for electrical and electronic equipment and no vaccine for humans (there is a vaccine for horses).

More than 85 cities were at high or critical risk for electrical and electronic equipment, and state health officials urged people not to be outdoors in the evenings when the mosquitoes are most active. From sporting events to trick or treating on Halloween, activities have been postponed or canceled to avoid exposure. Twelve people became ill and three died – the highest number since the 1950s.

Of course, those numbers pale when compared to the more than 104,000 people diagnosed with COVID-19 in Massachusetts this year. Because of this, public health officials are concerned that people may not be susceptible to warnings about mosquito and tick-borne diseases such as Lyme disease, electrical and electronic equipment, or the West Nile virus.

How big is the threat?

There’s no way of telling what kind of year it will be for EEE or West Nile Virus, said Cummings School Professor Sam Telford, an internationally recognized expert on tick and mosquito-borne diseases, a commissioner for the Central Massachusetts Mosquito Control Project, and a member of the state-owned Mosquito Advisory Group.

“If we knew it would be of great help, but there are variables that can be paradoxical, such as rain,” he said. For example, less rainfall could mean fewer breeding grounds for mosquitoes, which would result in fewer mosquitoes and, therefore, fewer cases of virus transmitted. But that’s just not true.

“In fact, less rain can mean even more West Nile Virus, as the main mosquito for West Nile Virus, the house mosquito, likes very organic, rich fluids. When gutters and sewers dry out because it doesn’t rain, the remaining water contains more organic matter for the larvae to feed on and produce bigger and better mosquitoes, ”Telford said.

The same complication exists with electrical and electronic equipment and the cattail mosquito, which Telford calls “the most dominant pest in July”. Cattail mosquitoes are the carriers responsible for transmitting electrical and electronic equipment from birds to humans. Their larvae spend the winter frozen in the mud of the swamps. In order to survive, the larvae need rain to cover the mud and develop. Without them they die, said Telford.

“This year there is a lot of water in the swamps and we could expect there to be more mosquitos. On the other hand, more water could mean that arthropods such as water beetles or dragonflies also breed well and hunt the larvae, ”he explained.

This uncertainty is why the state does not typically encourage preventive spraying to kill mosquitoes. In general, strikes have only been approved for public health purposes when officials know there will be a problem – as it will be this year, Telford said. In Central Massachusetts, for example, mosquito control measures targeting larvae are already in place.

“We know that the EEE virus occurs in three and seven year cycles. It’s three years here and then seven. This is the second year of a three year cycle, so we expect eastern equine encephalitis in Massachusetts in 2020, ”he said. “Usually, virus transmission in birds and mosquitoes begins in late June and the risk to humans usually increases in August as it takes a while for it to amplify in nature and reach levels where it spreads to humans.”

The forest was a safe haven from COVID-19, but with the tick and mosquito season here, precautions beyond a face mask are required. Wearing insect repellent from head to toe can protect against bites from mosquitoes, ticks, and black flies. (You can find more ways to protect yourself from electrical and electronic equipment here.) Repellants should always be used according to the instructions on the product label.

Telford wondered if there might be more cases of Lyme disease or electrical and electronic equipment reported this year just because more people are in the forest due to the COVID lockdown. While that remains to be seen, one thing is certain: It will be a busy summer for public health officials.

Angela Nelson can be reached at angela.nelson@tufts.edu.

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