Dengue, yellow fever, Zika or chikungunya are diseases that we associate with countries like Colombia, Tanzania or Malaysia, but that we could never imagine could reach the Mediterranean. And it shouldn’t, because the mosquitoes that serve as carriers – vectors in technical parlance – shouldn’t thrive in our environment. But thanks to climate change and the globalization of communications, Spain, among other countries, has become their new home. It is not strange because the increase in temperature has allowed them to survive in places that do not resemble a tropical ecosystem at all, even at 2,300 meters above sea level.
Guilty? A minimal being, a mosquito called Aeades aegypti , which is responsible for more than 50 million sick people and 25,000 deaths a year , according to the WHO. Transmitter of malaria, dengue, Zika fever, chikungunya and the Mayaro virus, it has an ally in its first cousin, the Aeades albopictus , better known in these parts as the tiger mosquito due to its peculiar black and white stripes and is included in the list of the 100 most harmful invasive alien species in the world produced by the International Union for Conservation of Nature. He arrived in our country from Asia in a shipment of tires and has been planting his reals throughout the Mediterranean basin.
A. albopictus has found a five-star hotel in our cities. Their larvae develop in any place where there is a small amount of water , better if it is in shady places. And for them, cities are jauja: jugs, buckets, vases, flowerpots … any object that contains a small amount of water in our gardens, patios, streets and open spaces. Even the water accumulated in a plastic cap is worth it. In this way, the tiger mosquito has gone from a quiet life in the countryside, where its original larval hatchery was the holes with water in trees, to an urban existence, full of places to reproduce and, of course, with a good number of humans. from which to feed. Unlike the mosquitoes we are used to, Aeades bite during the day, move close to the ground and do not emit the classic buzzing sound. As is normal, it is the females that bite as they need blood (and water) for their reproduction.
Dengue is the second most common mosquito-borne disease
It was detected for the first time in Spain in greenhouses in San Cugat del Vallés in 2004, and has been responsible for mild outbreaks of chikungunya in Italy in 2007 and West Nile fever in Greece in 2010. In our country this mosquito is responsible for us being one of the 110 countries with dengue: since October 2018 there have been 7 cases , luckily mild.
For its part, Latin America is experiencing the most intense dengue epidemic in its history. Costa Rica, for example, has seen the number of infections increase from 2019 to 2020 by 76%, as confirmed by the Ministry of Health of this Central American country. At the beginning of last February the city of Cali (Colombia) had to decree the yellow alert when it saw how dengue cases had skyrocketed by 500% in less than a month, and Brazil has more than 2 million people affected.
We are not facing a new disease; the first case of dengue fever recorded in a medical journal dates from the third century in a compendium of medicine from the Chinese Jin dynasty. Currently, it is known that there are 4 types of dengue virus, and having survived one does not imply immunity for the other three. Very similar to a flu, there is no specific treatment or vaccine and the only thing that can be done is to alleviate the symptoms and give life support to the most serious cases. Today dengue is the second most common disease transmitted by a mosquito in the world, where every year between 50 and 100 million people suffer from it and it has a mortality rate of 2.5%.
In addition to a vaccine -which will take time to appear- the other front is to end the mosquito, which is not easy either. Today we are working on different biological mechanisms for controlling pests, such as inoculating a bacterium that prevents them from reproducing or using their natural predators, such as the copepod microcrustaceans Mesocyclops thermocyclopoides . The only certain thing is that we cannot lower our guard, even more so when in 2017 the Aeades aegypti was detected in the Canary Islands.
And he has come to stay.
