So why do mosquitoes bite some people more and how are they so effective in spreading diseases?
Professor of Salamanca University. Raúl Rivas González replied:
In fact, according to statistics, the mosquito is by far the deadliest creature on earth for humans.
It caused about 725 thousand deaths in 2018 alone.
In the same year, the second factor that caused the most loss of life was the person himself, who killed 437 thousand people. This was followed by attacks by snakes, dogs, venomous snails, crocodiles, hippos, elephants, lions, wolves and sharks.
Because of this alarming situation, the World Health Organization approved in 2017 the “Global Vector Control Response (GVCR) 2017–2030” guideline to guide countries to control mosquito-borne vectors-borne diseases.
This is critical for preventing diseases and responding promptly to outbreaks that may arise.
mosquitoes; West Nile virus, Zika virus, dengue fever, yellow fever, chikungunya, St. Louis encephalitis, lymphatic filariasis, La Crosse encephalitis, Pogosta disease, Oropouche fever, Tahyna virus, Rift Valley fever, Semliki Forest virus, Sindbis fever, Japanese encephalitis, Ross River fever, Barmah Forest virus or malaria.
In this way, there were 627 thousand deaths in 2020 alone.
So why do mosquitoes bite people and why do some become more targets?
CARBON DIOXIDE AND BODY Odors
Both male and female mosquitoes can actually live without biting other animals. However, females need blood to complete their reproductive cycle.
About 100 years ago, it turned out that carbon dioxide (CO₂) attracts mosquitoes.
However, the attraction of carbon dioxide does not explain why mosquitoes systematically prefer one person over another.
There are other physical and chemical signs that make mosquitoes more attracted to certain people.
These include heat, water vapor, humidity, visual causes, and most importantly, odors emanating from the skin.
Although it is not yet fully understood which flavors attract mosquitoes the most, molecules such as indole, nonanol, octenol and lactic acid stand out in many studies.
a research team led by Matthew DeGennaro of Florida International University in the USA; He discovered that there is a unique olfactory receptor known as IR8a, which allows Aedes aegypti mosquitoes, which carry many diseases, to detect lactic acid.
When the scientists mutated the IR8a receptor on insect antennae, they found that mosquitoes were unable to detect lactic acid and other acidic odors emitted by humans.
ODOR ATTRACTING Mosquitoes
On the other hand, according to recent research, dengue and Zika viruses change the smell of mice and the people they infect, making them more attractive to mosquitoes.
This supports the situation that they take the infected blood by biting the sick person and then transmit the virus to others.
Normally, the skin of humans and rodents produces an antimicrobial peptide that limits bacterial populations.
However, in mice infected with dengue or Zika, the density of this peptide decreases and some bacteria multiply, triggering the production of acetophenone (the simplest aromatic compound).
A similar situation exists with humans. Fragrances collected from the armpits of dengue patients contain more acetophenone than those of healthy people.
The interesting thing is that this is fixable. Some of the dengue-infected mice were treated with isotretinoin, which resulted in less acetophenone release, thus reducing mosquito attraction.
Thus, mosquito bites are prevented.
These determinations of why mosquitoes prefer to bite a human could help reduce diseases transmitted by vectors.