Infected mosquitoes have killed more people than all wars in recorded history. In fact, statistics show that the mosquito is still the deadliest creature to humans.

About 725,000 mosquitoes died in 2018 alone. The second leading cause of human death that year was other humans, accounting for 437,000 deaths. Trailing behind are snakes, dogs, venomous snails, crocodiles, hippos, elephants, lions, wolves and sharks.

This alarming situation led to the World Health Assembly in 2011. There is an urgent need to control the vectorsEspecially mosquitoes.

Vector control is essential to prevent mosquito-borne disease and prevent outbreaks. These insects can transmit various diseases such as West Nile fever. Zika, dengue, yellow fever, chikungunya, St. Louis encephalitis, lymphatic filariasis, La Crosse encephalitis, Pogosta disease, Oropoche fever, Tahina virus disease, Rift Valley fever, Semiliki forest virus infection, Sindbis fever, Japanese encephalitis, Ross River virus disease, in 2020 Only 627,000 people died from Burma forest virus disease and malaria. It is understandable why people want to know what makes mosquitoes bite one person and not another.

Carbon dioxide and body odor

Male and female mosquitoes can live without biting other animals, but females need blood to complete the reproductive cycle. Carbon dioxide (CO₂) was identified as a mosquito attractant nearly a century ago. This gas is used to trap blood-feeding female mosquitoes with the nutrients needed for oogenesis, or egg production.

However, there is no evidence of CO₂ labeling. Different attraction. In other words, carbon dioxide emissions don’t explain why mosquitoes prefer one person over another. So what is the explanation? There are other physical and chemical cues that attract mosquitoes, such as heat, water vapor, humidity, visual cues, and most importantly, body odor.

Although the most attractive odors for mosquitoes are not well known, several studies point to molecules such as indole, nonanol, octenol, and lactic acid as prime suspects. A team of researchers led by Matthew DeGenaro at Florida International University has identified a unique odorant receptor known as ionotropic receptor 8a (IR8a). Egyptian temples Mosquito to detect lactic acid. This type of mosquito is a known vector of dengue, chikungunya and Zika. When the scientists altered the IR8a receptor on the insect’s antennae, they found that the mosquitoes were unable to distinguish lactic acid and other acidic odors from humans.

Acetophenone, a ‘perfume’ that attracts mosquitoes

Recent research suggests that the dengue and zika viruses can change the odor of rodents and the people they infect, making them more attractive to mosquitoes. This is an interesting mode of transmission, because it encourages mosquitoes to bite the host, extract the infected blood and transmit the virus to another person. Viruses achieve this by modulating the release of an aromatic ketone – acetophenone – that is particularly attractive to mosquitoes.

Human and mouse skin produce an antimicrobial peptide that normally controls bacteria. However, in mice infected with dengue or Zika, the amount of this peptide decreases, and some bacteria (genus Bacillus) multiply, which causes the production of acetophenone. The same thing happens in humans: Odors collected from the armpits of dengue patients have been found to contain more acetophenone than healthy people.

Interestingly, this enhanced acetophenone emission can be modulated. Some dengue-infected mice were treated with isotretinoin, which reduced acetophenone emissions, making the host less attractive to mosquitoes.

Microbes that change odors

This is not the only example of a microorganism manipulating the physiology of mosquito and human hosts to enhance the pathogen. For example, infected people Plasmodium falciparumThe parasite that causes malaria is more attractive than healthy people. Anopheles gambiae Mosquitoes, the vector of the disease.

The reason for this is not known, but it may be related to this Plasmodium falciparum (E)-4-Hydroxy-3-methyl-but-2-enyl pyrophosphate (HMBPP) produces an isoprenoid precursor that impairs mosquito blood-seeking and blood-feeding behaviors as well as disease susceptibility. Specifically, HMBPPPPPPPPI.

Also add HMBPP to blood samples It greatly strengthens attraction. Like other mosquito species Anopheles coluzzi, Anopheles arabiensis, Aedes aegyptiAnd some of the Culex pipiens/Culex torrentium Complex.

Understanding the factors that make some people more attracted to mosquitoes than others can help identify and reduce the risk of vector-borne diseases.

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