Warmer Climate and Disease-Carrying Pests

Higher temperatures mean more favorable conditions for disease-carrying pests in Connecticut, such as ticks and mosquitoes.

Ticks carry Lyme disease and mosquitoes carry West Nile virus, so any increase in the populations of these pests is cause for concern.

In the Hartford area, for example, the mean annual temperature has increased one point five degrees Fahrenheit since 1950, from 49.5 degrees to 51 degrees in 2014.

A similar trend exists in the Bridgeport area, which is the official climate site on the Connecticut shoreline. Since the halfway point of the previous century, the mean annual temperature has risen one point eight degrees Fahrenheit from 51.2 degrees to 53 degrees in 2014.

Mosquitos spread West Nile virus, and one species called the Asian tiger mosquito is particularly invasive.

According to a 2013 report by Rochlin et al., the amount of land suitable for the Asian tiger mosquito to survive is expected to increase from five to 16 percent in the next two decades.

Making clear the Asian tiger mosquito is known to have substantial biting activity and a high potential to spread disease, the report indicates populations currently exist across portions of Pennsylvania, New Jersey, Long Island and coastal southwestern Connecticut.

Under a scenario with a moderate increase in carbon dioxide emissions and thus continued warming of the earth, the study projects the majority of Connecticut will be dealing with this invasive species by the year 2039, including the entire Connecticut River Valley.

According to Climate Central, mosquitoes have a high mortality rate when temperatures are outside the range of 50 to 95 degrees Fahrenheit. Additionally, relative humidity below 42 percent is unfavorable for mosquitoes.

Connecticut mosquitoes aren’t the only pests that benefit from warmer air.

Ticks, of course, are responsible for the spread of Lyme disease.

More than a decade ago, a study by Brownstein et al. surveyed the expected changes in tick habitats across eastern North America. While a decrease in the amount of land suitable for ticks was projected for the 2020s, the long-term expectation was alarming.

By the 2080s, the net increase in suitable land for ticks is projected to be 68.9%, with major jogs north into Canada.

With ticks in more areas, more people have the potential to come into contact with them.

“Human cases of Lyme disease, and other tick-associated illnesses, Babesiosis and Anaplasmosis, have also increased during the last few decades in the state, for which climate-related factors are among the contributing factors,” said Dr. Goudarz Molaei, a research scientist at Connecticut’s Center for Vector Biology and Zoonotic Diseases.

A warming climate may mean more than just expanded territory for ticks.

Goudarz says “warmer winter seasons could provide a favorable condition for ticks to successfully overwinter and emerge in the spring. Apart from some extreme and unusual conditions, we have witnessed shorter winter seasons and warmer temperatures during the last few decades or so in the northeastern U.S. including Connecticut.”

Though an increase in Lyme disease reports is likely in part due to increasing deer populations, more ticks in more areas is likely part of the equation, according to Climate Central. It expects the upward trend to continue with a warming climate since warmer weather is more supportive of tick populations.

More ticks and a longer mosquito season are just some of the implications from climate change in Connecticut, but other implications often receive more attention.

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