DENGUE, an endemic disease in India

The world of viruses has become more familiar to us in the last three years. The experts explained to us how they work and made us understand that until further notice, the battle we are waging against them rarely turns out in our favor.

The editorial staff contributes to our knowledge by focusing on dengue fever, which is widespread in India, particularly in Tamil Nadu.

Dengue fever, a virus transmitted to humans by mosquitoes

The term “dengue fever” comes from Swahili, an African language, and means “trouble caused by an evil spirit.” The evil spirit in this case is a virus transmitted to humans by a mosquito, the tiger mosquito, of the genus singers. It should not be confused with the mosquito vector of malaria, the famous Anopheles.

Dengue, an endemic disease in India

Half of the world’s population is now considered to live in a dengue risk zone (about 130 countries). Between 2000 and 2019, the number of cases increased eightfold (5.2 million cases in 2019). 70% of infections are recorded in Asia.

Since 1990, India has experienced many epidemic phases. In 2009 there were 82,300 cases. In 2021, the number of infections was 193,245. The actual number of cases is underestimated because most are mild or even asymptomatic and therefore undiagnosed. In 2017, a study of 60 Indian districts found a seroprevalence of 49%.

In 2021, Uttar Pradesh (29,750 cases), Punjab (23,389), Rajasthan (20,749), and the city of Delhi (13,089) accounted for 45% of cases. Tamil Nadu had 6,039 infections for the same year and Pondicherry 1,625.

At the end of August 2022, the total for Tamil Nadu was 3,528 cases; the extrapolation for the whole year reaches a level equivalent to 2021, with cases multiplying in the monsoon season, at the end of the year.

The dengue/mosquito virus duo singers

Therefore, dengue is an infectious disease caused by a virus. There are four variants of the virus in action and, unfortunately, the immunity provided by infection of one variant does not protect against the other variants.

The disease is often asymptomatic. It is manifested by a sudden fever associated with severe pain and rash. In rare cases, serious complications can occur.

Originally, dengue is an infection that occurs in tropical or intertropical areas. The globalization of trade and global warming mean that today the disease spreads in more temperate territories.

To expand its field of action, the virus takes advantage of the mobility of its means of transport, the mosquito. singers. There are several types of mosquitoes singers. In India, there are two types, the mosquito Aedes albopictus and the mosquito egyptian aedes.

L’aedes albopictus, called a tiger mosquito, it can be identified by its black and white striped legs, it travels in containers and even on tires. Their eggs can survive a long time in a dry environment, but as soon as there is a little water to moisten them, they hatch and multiply. L’egyptian aedes also has black and white striped legs but differs fromAedes albopictus on the thorax that is adorned with a lyre. just the mosquito Aedes albopictus it spread throughout the world until it reached temperate zones such as France.

In France, the tiger mosquito is present today in 67 metropolitan departments. According to the latest figures published by the Public Health France site, in 2022 at the moment, 139 imported cases of dengue (contracted abroad and incubated in France) and 16 autochthonous cases have been diagnosed in France.

the female mosquito singersa sewing day

It is the female that bites to feed on our blood. She mainly performs during the day (unlike Anopheles which itches in the second part of the night). It is very aggressive at dawn and dusk.

When the mosquito bites a person infected with dengue, the collected virus multiplies in their stomach for about ten days. So the dose is strong enough to infect the next person bitten. The first signs of the disease occur after the incubation phase, which lasts an average of 4 to 7 days.

singersan urban mosquito

singers it is a predominantly urban mosquito. The females lay their eggs in small spaces likely to collect water: vases, saucers, used tires, poorly emptied gutters, various waste containing stagnant water, plants likely to form water retention (bamboo, traveller’s tree…).

singers it does not like large bodies of water or rivers.

This is one of the reasons behind the geographical distribution of infections in India. The vast majority are concentrated in cities or densely populated areas.

Studies have shown that families without access to running water are at increased risk of contracting dengue. They are forced to store stagnant water and thus provide privileged niches for egg laying.

Unplanned urbanization, the absence of water supply and drainage systems, the accumulation of waste in India create ideal conditions for the proliferation of mosquitoes. Rising temperatures and changes in rainfall patterns are aggravating the situation. Finally, preventive measures to contain the epidemic are not systematic and remain ineffective.

How to protect yourself from mosquitoes singers

There is no specific antiviral treatment for dengue. In case of suspicion, the most common diagnostic method is the detection of antibodies by serology. An effective vaccine for everyone is being studied.

The only effective prevention is to protect yourself against mosquito bites: repellent sprays or creams, coils, electric diffusers, long clothing, mosquito nets. Everything is good.

It must be remembered that singers it bites during the day and that it is a small insect that stays at ground level most of the time. Therefore, the feet and legs should be covered in priority.

Elimination of all potential sites for egg laying and hatching of larvae is also essential: no standing water in saucers and other containers.

At the collective level, the fight against mosquitoes today takes various forms: insecticide spraying, release of sterile male mosquitoes, release of fish that feed on mosquito larvae in ponds, etc.

The means developed in India are still limited and the population is not aware enough to win the game.