Climate change bringing more mosquitoes and mosquito-borne diseases

By LAURA AUGENBRAUN | UConn Journalism 
Jan­u­ary 18, 2022

Evan White was in his sec­ond to last lacrosse sea­son at Foran High School in Mil­ford, Con­necti­cut in spring of 2019, when sud­den­ly his team start­ed hear­ing rumors of their games being resched­uled and even canceled.

It was actu­al­ly real­ly scary because we weren’t sure what was going to hap­pen,” White said.

While can­cel­la­tions and shut­downs have become com­mon­place dur­ing the COVID-19 pan­dem­ic, pri­or to March 2020 game can­cel­la­tions were rare. But an unusu­al­ly high amount of mos­qui­toes in Con­necti­cut test­ing pos­i­tive for East­ern Equine Encephali­tis — more com­mon­ly known as triple E — had altered the 2019 spring and fall sports seasons.

Triple E is an extreme­ly rare but high­ly fatal dis­ease that is trans­ferred from mos­qui­toes to humans. In Con­necti­cut in 2019, 122 mos­qui­toes test­ed pos­i­tive for car­ry­ing the dis­ease, and four peo­ple con­tract­ed EEE. Out of those four peo­ple, three died.

I remem­ber it get­ting warmer out and hear­ing about it, and then I remem­ber trav­el­ing on the high­way and there was a sign that said “Warn­ing, EEE. Dawn to Dusk Watch” and I just remem­ber think­ing wow, this is actu­al­ly kind of crazy,” White said.

Games orig­i­nal­ly sched­uled for 7 p.m. were resched­uled for 4 p.m. so ath­letes and spec­ta­tors would not be out at dusk, when mos­qui­toes are most active.

Now sci­en­tists have begun to research whether the increased num­ber of mos­qui­toes seen in 2019 may be the new nor­mal as cli­mate change con­tin­ues to alter the state our earth is in.

I think the big con­cerns when we look at mos­qui­toes and mos­qui­to-borne dis­eases are going to be things like the changes that are occur­ring due to cli­mate change, glob­al­iza­tion, and due to envi­ron­men­tal defor­esta­tion,” Doc­tor Philip Arm­strong, Virol­o­gist and Med­ical Ento­mol­o­gist at the Cen­ter for Vec­tor Biol­o­gy and Zoonot­ic Dis­eases in New Haven, said.

Due to human-induced cli­mate change, New England’s tem­per­a­ture is expect­ed to rise, fur­ther increas­ing the mos­qui­to pop­u­la­tion and elon­gat­ing the mos­qui­to sea­son into the fall and win­ter months. Arm­strong said the mos­qui­to pop­u­la­tion has already increased 40% over the last 20 years, with many new types of the insect that once were found only in the South, now trav­el­ing north.

It all comes down to cli­mate change. We’re see­ing these more extreme changes hap­pen­ing, and over­all things will get warmer, but we’re going to see both extreme hot and cold and also more extreme pre­cip­i­ta­tion, espe­cial­ly here in the North­east,” Dr. Tal­bot Andrews, an assis­tant pro­fes­sor in the Depart­ment of Polit­i­cal Sci­ence at the Uni­ver­si­ty of Con­necti­cut said. Andrews’ online biog­ra­phy notes her work focus­es on “how insti­tu­tions, pub­lic pol­i­cy, and the phys­i­cal envi­ron­ment shape pref­er­ences and behav­ior relat­ed to cli­mate change.”

We’re see­ing longer sum­mers and hot­ter sum­mers, and it’s not like the win­ters over­all get cold­er, it’s that we get more of these things like the bomb cyclone. So you get these short weeks where we just get crazy snow, but over­all the win­ters will get short­er,” Andrews said.

The North­east will also endure more dis­as­trous weath­er events that bring large amounts of rain­fall when the weath­er is warmer. More rain­fall brings more stand­ing water. The com­bi­na­tion of this, along with warmer tem­per­a­tures that linger fur­ther into the cold­er months, is why researchers are doc­u­ment­ing more mosquitoes.

Mos­qui­toes as a group are very, very good at exploit­ing dis­turbed habi­tats and dis­tur­bance. They have a boom and bust life cycle and they sort of take advan­tage of lit­tle tem­po­rary pools of water that we cre­ate for them, so they’re real­ly quite adapt­able,” Arm­strong said.

The increase in mos­qui­toes also rais­es the con­cern of see­ing more infec­tions of mos­qui­to-borne ill­ness­es in the human pop­u­la­tion. In the North­east those dis­eases are Triple E, West Nile Virus, and some Yel­low Fever cases.

To try to pre­vent infec­tions, sci­en­tists like Arm­strong watch weath­er con­di­tions and con­stant­ly test mos­qui­toes in cer­tain areas for these dis­eases. Once it is con­firmed that there are cas­es of a virus in a cer­tain area, they begin to noti­fy the public.

If we have evi­dence that it is head­ing in that direc­tion, we’ll con­tin­ue to do more pub­lic health mes­sag­ing and we’ll work with the local health dis­tricts and they will start to con­sid­er oth­er mea­sures like shut­ting down parks, ban­ning overnight camp­ing in sites that are at risk, cur­tail­ing out­door activ­i­ties based on the risk,” Arm­strong said.

A last resort effort, if cas­es begin to increase sig­nif­i­cant­ly, is spray­ing the heav­i­ly infect­ed areas with chemicals.

Lim­it­ing out­door activ­i­ty sounds sim­i­lar to the pre­cau­tion­ary mea­sures and quar­an­tine peri­ods imposed dur­ing the COVID-19 pan­dem­ic, but accord­ing to both Arm­strong and Andrews, mos­qui­to-borne dis­eases do not have the abil­i­ty to cre­ate a wide spread pandemic.

With these dis­eases, they’re what we call ‘zoonot­ic infec­tions,’ so that means that these are main­tained in nature out­side of human pop­u­la­tion. So with West Nile virus and Triple E virus, birds are actu­al­ly the car­ri­er of the virus, they’re the source of infect­ing mos­qui­toes, so it’s main­tained in this mos­qui­to-bird cycle, and occa­sion­al­ly a mos­qui­to that nor­mal­ly feeds on birds will feed on a per­son and they get infect­ed, but that virus, there’s no sub­se­quent con­ta­gion to anoth­er per­son, we’re a dead end host. So that changes things a lot. That’s a big, impor­tant dis­tinc­tion to make,” Arm­strong said.

Although these dis­eases do not have the con­ta­gion sim­i­lar to that of COVID-19, there is still cause for con­cern that may keep peo­ple indoors as mos­qui­toes increase. Dur­ing White’s last lacrosse games, he and his team­mates noticed a decrease in spec­ta­tors even after the games were rescheduled.

My team was nev­er mad about get­ting the games moved, but we def­i­nite­ly saw a loss of old­er, usu­al spec­ta­tors,” White said, his