Northern countries are at risk of outbreaks of dengue, Zika and chikungunya as climate change increases the range of the mosquitoes that carry these illnesses, according to the World Health Organization.
(Bloomberg) — Northern countries are at risk of outbreaks of dengue, Zika and chikungunya as climate change increases the range of the mosquitoes that carry these illnesses, according to the World Health Organization.
As climate disasters occur with greater frequency, experts are concerned that insect-borne diseases will become more common, including in regions of the world where they’re not currently a threat. This is what has happened this year in southern hemisphere countries that have just had their summer, when the number of mosquitoes typically grows.
“Climate change has played a key role in facilitating the spread of the mosquitoes down south,” Raman Velayudhan, the WHO’s global program head on control of neglected tropical diseases, said in a briefing Wednesday. “And then when people travel, naturally the virus goes along with them.”
This year there have been almost 442,000 cases of dengue in the Americas alone, with about 120 deaths. Half of the world’s population is now at risk of the disease, with as many as 400 million infections occurring each year, according to the WHO. The same mosquito is a conduit for all three diseases, and so the trio often co-circulate.
Although most people who get dengue for the first time experience mild disease with a simple fever and body ache, some who contract it a second time end up with a severe case, which can lead to organ failure and death. There is no treatment for dengue and a new vaccine is only starting to gain traction.
One of the biggest challenges in controlling these arboviruses is that the mosquito eggs can remain dry for several months while traveling in containers, only to hatch in a new country within a few hours of coming in contact with water. The mosquito spreading the disease, which bites during the daytime, also has a habit of moving between several people in one go, Velayudhan said.
Increased rainfall, higher temperatures and in some cases scarcity of water can favor the breeding of the insects, Velayudhan said. Still, several “tools are under development which provides greater hope in preventing and controlling dengue,” he said.
These include better diagnostics, antivirals, two further vaccines that are under final phase 3 trial and review as well as methods to control the mosquito such as measuring which types of insecticide it’s resistant to. Changing the bacteria within the mosquito’s gut and making the male insect sterile are two further controls being examined.
“They’re spreading by altitude and by latitude,” said Diana Rojas Alvarez, the WHO’s co-lead of the global arbovirus initiative. “There are cases reported now in the south of Europe,” she said, holding up a map showing rapidly growing incidences in Italy.
In a similar way to Covid-19, which was a novel disease in humans, an increased presence of mosquitoes carrying arboviruses may result in a new mosquito-borne disease emerging, especially in areas with a lot of people, she said. “If the population is susceptible then there is a risk to have large epidemics in these regions.”
(Updates number of people affected and new tools being developed from fourth paragraph)
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