Mosquitoes could be the sole species to be benefitting from climate change, as the warmer and wetter weather that comes with global warming makes for their ideal environment.
Thanks to this, the insects are growing bigger and living longer, increasing their ability to pick up and spread potentially deadly diseases.
Bites from the blood-sucking bugs are more than just an annoyance – different species can carry infectious diseases including dengue fever, Zika virus, yellow fever, chikungunya virus, malaria, and West Nile virus that they pick up from one person and pass it on to the next.
Mosquito-borne disease experts are concerned that as global temperatures continue to rise, warmer, more humid weather will become the norm in new places, making those locations the perfect breeding grounds for mosquito populations to flourish.
And as temperatures heat up and mosquitoes migrate to places they previously couldn’t thrive in, their extended reach and longer lifespans give them ample opportunity to spread diseases in new parts of the world.
The most concerning mosquito-borne diseases in the US come from the Aedes aegypti, which is known to transmit dengue virus, yellow fever virus, chikungunya virus and Zika virus
The Aedes aegypti variety is known to cause more uncomfortable itching than some others
Climate change is one of the most pressing and politically-charged issue, and is set to bring higher temperatures in previously temperate regions, more extreme weather, and increased flooding, all of which are factors that encourage a growing population of bigger mosquitoes that stick around for longer periods.
Global average temperatures have risen by about 2 degrees Fahrenheit Since the late 1800s, with most of the increases occurring over the past 50 years.
The amount of water vapor in the atmosphere has risen as a result, about one to two percent every decade, according to the United Nations.
Dr Photini Sinnis, Deputy Director of Johns Hopkins Malaria Research Institute, told DailyMail.com: ‘The most important thing for mosquitoes and mosquito longevity is humidity.’
As greenhouse gases trap heat within the atmosphere, temperatures on Earth climb, which in turn leads to increased evaporation from water sources on land, including lakes and rivers. And warm air holds more water vapor.
Increased water vapor in the atmosphere is part of a feedback loop because it absorbs and re-emits heat, making it the most abundant greenhouse gas.
A bulked-up capacity to hold onto water vapor fuels extreme weather events, including hurricanes and flash-flooding.
This is being borne out by the data, as the last five years have seen an average of 18 severe weather events annually, up from an average of 13 per year in the decade between 2010 and 2020.
As major weather disasters such as extreme storms become more common due to climate change, ideal living conditions for mosquitoes will become more common. This could increase the risk these insects pose to the general population
Clusters of malaria cases in the US are not unheard of. They are almost always linked to international travel to parts of the world where local transmission is common because in order for a mosquito to spread malaria, it has to bite a person already infected
When rainwater from major storms collects in garbage bins, buckets, and puddles, they can become settlements for mosquitoes, which lay around 100 eggs at a time.
A male mosquito’s lifespan is typically seven to 14 days, but female mosquitoes – which are the only ones that actually feed on blood and transmit disease – live for an average of six weeks.
The variety of particular concern for the US is the Aedes aegypti, which is known to transmit dengue virus, yellow fever virus, chikungunya virus, and Zika virus. This variety is also known to cause more uncomfortable itching than others.
Dr Sinnis said: ‘Aedes can live in urban areas. They can lay their eggs in temporary pools of water, in an old tire or something. And they’re well adapted to our environment.
‘So where you have large concentrations of humans and where it’s warm enough and humid enough for them to thrive, they will move in.’
Over the past two decades, dengue fever outbreaks have been detected throughout the US.
Dengue is not endemic to the US, which means cases in the country often occur in isolated clusters. They are typically linked with international travel, but locally acquired cases are especially concerning because they signal the virus could be actively spreading through an environment where it should not be.
So far this year, more than 500 cases linked to international travel and 433 locally acquired cases of dengue fever have been reported in the US.
Last year, the number of cases surpassed 2,200.
Dengue, nicknamed the ‘bone-breaking disease’ for its trademark joint and muscle pain so severe it feels as if your bones are breaking, is a virus that typically runs its course and resolves.
But in as many as one in 20 cases, it can lead to bleeding and organ failure.
In addition to crippling joint and bone pain, the infection can lead to sudden high fever, headache, pain behind the eyes, and skin rash.
Dengue can turn deadly if it progresses to dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS), which can lead to severe bleeding and organ damage.
But those situations are fairly rare. Less than one percent of dengue cases turn out to be fatal.
Yellow fever poses a high risk of outbreaks in 40 countries, generally tropical areas of Africa and Central and South America, but not the US.
It causes jaundice, a condition marked by yellowing skin due to a build up of a substance called bilirubin in the bloodstream. It can also lead to hemorrhagic fevers brought on by viruses, causing severe internal bleeding, damage to the blood vessels, and different organ systems.
By the time a person with yellow fever develops jaundice, their risk of dying reaches 20 percent and climbs from there.
Chikungunya is a lesser-known virus, but is present in 115 countries, and the US is at a low risk. It can cause severe arthritic pain, but it is very rarely fatal.
Zika virus, which passes from pregnant mother to baby, can cause a rare birth defect known as microcephaly, in which a baby is born with an abnormally small head.
But only 1 in 5 people infected with Zika exhibit any signs of illness and hospitalization and death are rare.
The more dangerous Aedes mosquitoes, particularly Aedes aegypti and Aedes albopictus, can pick up any of these pathogens when they bite a person already infected with the virus. It then enters the mosquito’s digestive system, replicates, and multiplies.
The virus invades the mosquito’s other tissues and eventually reaches its salivary glands. The next time the infected mosquito bites a human, its saliva is deposited into the skin and enters the bloodstream.
Dr Sinnis said: ‘In terms of the diseases transmitted by Aedes aegypti, I would worry in sort of the southern states, most of all, Florida, but Georgia as well.’
Current modeling projects that in the worst-case scenario that sees little to no action on remedying climate change, 89.9 percent of the global population will be at risk of dengue fever by 2080.
In addition to the Aedes aegypti mosquito, experts are also becoming increasingly concerned about living conditions that the Anopheles mosquito thrives in. This is the type of mosquito that carries the malaria parasite.
Clusters of cases in the US are not unheard of. This year, there have been seven cases of malaria in Florida and one each in Texas and Maryland.
And these disease-bearing mosquitoes are already expanding their range.
A February report authored by Georgetown University researchers found the Anopheles mosquito species has gained about 21 feet in elevation in their native southern Africa every year over the past 120 years, meaning climate change is helping these species survive in colder previously-unlivable environments.
Malaria cases in the US are almost always linked to international travel to parts of the world where local transmission is common because in order for a mosquito to spread malaria, it has to bite a person already infected.
Dr Sinnis said: ‘Malaria is unlikely to become as big a deal [in the US] as it is currently in Sub-Saharan Africa and parts of Asia, we just don’t have the factors necessary for that kind of intense transmission. So if it happens, it’s not going to happen anytime soon.’
WHY DO MOSQUITOES BITE SOME PEOPLE AND NOT OTHERS?
Around 20 per cent of people are more prone to mosquito bites.
And while scientists are yet to find a cure, they do have some ideas as to why the insects attack some of us more than others.
Certain blood types are more attractive to taste buds of mosquitoes.
Research has shown that people who have Type O blood – the most common blood type – tend to get bitten twice as much as those with Type A. People with Type B blood get bitten somewhere in the middle.
Exercise and metabolism
Working up a sweat during exercise can also make a person more susceptible to a mosquitoes bite.
Strenuous exercise causes higher body temperatures and a buildup of lactic acid, which emit yummy signals to the insects.
A cold glass of beer makes you sweat and your body release ethanol, which may be why mosquitoes like to land on beer drinkers.
Levels of bacteria on the human skin can entice mosquitoes to bite, particularly where bacteria clusters like on the ankles and feet.
Having different types of bacteria on the skin, however, tends to turn the insects off.
Mosquitoes use even the faintest of human body odours when searching for potential victims.
It’s been known for some time that female mosquitoes use specific sensors around their mouths to detect carbon dioxide being exhaled from humans and animals.
But a few years ago, researchers from the University of California Riverside discovered the blood-sucking insects also use these same sensors to detect body odours – especially the smell of feet.