• Crimea-Congo, Zika, Chikungunya, Dengue .... This is the exotic virus that stalks us
  • The voice of Chagas' disease: the disease of America
  • You are not alone. The 200,000 bugs that hide in your home

Flies, mosquitoes, ants or moths are apparently harmless household insects. As long as they do not become a plague, we live with them at home without major problems. Those who bite or bite are annoying, but they are not a danger ... They are not, unless they infect us with a disease or with their little feet contaminate our food. So we can get a virus or intoxicate ourselves. Infections are frequent in the hot months, when they are most active, the lightest clothes and we, an easy target.

Throughout history, flies and mosquitoes have been very harmful, not for untiring us, but for transmitting a whole range of deadly microbes . In that case, we sleep next to an enemy that may be hidden on the prowl.

The scene is repeated anywhere in the world. A fly perches and, although we chase it away, it returns again and again. "Look at her. You just don't get tired, ”a shop assistant complains in a store. "I am much bigger than her, but she is not afraid of me," he says. The tenacity of these animals can end our patience, but the attitude of intrepid insects is also appreciated in different cultures. For the ancient Egyptians it was a symbol of indomitable courage, insistence and tenacity in the face of conflict. The fly "was the highest distinction granted by the pharaoh to his most prominent soldiers," writes Xavier Sistach in his book History of Flies and Mosquitoes (Harp). "Plutarch said that some infantry units of the Lancemon army were equipped with shields adorned with a large fly, to remind the adversary that like the insect, no matter how scared, they always return to the load, " continues the writer.

Mosquitoes, however, do not come out well in any of the 393 pages of Xavier Sistach. They do not doubt the bad reputation of the “most found criminal”, to whom he dedicates 10 of his 13 chapters, which begin with a one-eyed and lame copy that martyred for 40 years to Nemrod himself, the architect of the Tower of Babel according to Genesis. This is also one of the author's favorite quotes.

Did you know that if all the flies perched on the planet would occupy 149 million square kilometers?

Sistach, a specialist in ancient natural history of insects and collaborator of the Zoology Museum of Barcelona, ​​is a treatise on these two dipterans, as the two-winged insects are called. It compiles, with the thoroughness characteristic of every good entomologist, an extraordinary infinity of data. Did you know that if all the flies perched on the planet would occupy 149 million square kilometers ? The figure was calculated in 1903 by the naturalist Clifton F. Hodge, but it is debatable and its deduction surprising.

However, and beyond mere detail, the author delves into, above all, the terrible consequences that our coexistence with such harmful parasites has had for humanity. "Flies and mosquitoes are currently the most harmful insects for man . " They transmit more than one hundred different diseases, many of them fatal, as documented in a meticulous way in this work. Dysentery, cholera, malaria, yellow fever or dengue fever are just some of the evils associated with flies and mosquitoes that have decimated our population since the beginning of time. Most of them prevail in tropical regions and have been eradicated in developed countries where climate and control of transmitting vectors have allowed it. This is the case in Europe, where malaria was suffered in the past, a disease that today, according to WHO, still produces 600,000 deaths annually in endemic countries.

History has also witnessed serious cases of malaria during World War II in South Pacific fighters or serious episodes of yellow fever in unexpected places like Cádiz (in 1800) and Barcelona (in 1821). While a sixth of the population (about 11,000 people) was lost in Cádiz, in Barcelona there were between 16,000 and 20,000 deaths.

The chaos in the control of the sick , without trying to judge it with the eyes of now, was responsible for this high number of deaths. «The two yellow fever epidemics came from America, mainly brought by ships that returned from Havana or Veracruz, two cities intensely affected by this disease. On that occasion, as in so many others, the quarantines were not effective, ”says Xavier Sistach himself. “No one wanted to be locked up waiting to see the evolution of their status or that of the crew and the passage. If they could, they went down to the port and mixed with the local population, ”he explains.

In this way, from the ports of Cádiz and Barcelona landed patients with yellow fever and mosquitoes infected with the virus. "And what started as an outbreak became an epidemic that killed thousands of people while others fled in terror," says Sistach as he reflects on what happened. « The current population does not remember these facts , the memory is slight. In any case, in the cemetery of Poble Nou in Barcelona you can see the cenotaph that was erected in homage to the victims of yellow fever ».

Diseases that come or return

The exceptional jump of yellow fever to Europe at the beginning of the 19th century is not the only case of importation of a disease transmitted by insects that, if not for transport, would not reach such remote places where they do not live. Trade, migration and tourism contribute to the spread of species that spread diseases and coexistence with sufferers, increasing the risk of infection. Malaria and Chagas are the most common and already have an important impact on the health of countries like ours.

In the case of malaria, the mosquito of the genus Anopheles " continues to live among us and has the ability to transmit the infection," says Sistach. But for an epidemic to occur, many infected or many sick mosquitoes are needed to contact them. "This is not the scenario, in any case, of European or North American countries."

Chagas disease is a different case, because "despite being a serious health problem for various South American countries and people coming to our country with the disease on their backs, there is no transmitter here," the bug that carries the parasite.

However, when talking about dengue, chikungunya or zika, we cannot forget that the tiger mosquito, an invasive species, lives among us. For this great threat, "it will be necessary, to be very alert and extreme vigilance with possible indigenous cases and work to keep mosquito populations stable, because eliminating them seems like an impossible task today," Sistach warns.

The bad reputation of some insects for the transmission of diseases is evident in this book. He is not the first who writes this author on these issues, since he has already dealt with swarms, plagues and all kinds of "devastation" and "hecatombs" in his bibliography. With such distinguished protagonists and following the terminology of Sergio Leone's famous film, it would be interesting to find out who Xavier Sistach would be, among them all, the good, the ugly and the bad of entomology.

"The good one is Homoporus destroyer, " he says, a small hymenopter that parasites and ends up with huge amounts of Hesse's terrible fly, feared for the wheat plant. «An ugly insect is Ephippiger ephippiger », the chicharra alicorta. "I don't like his head at all, his face, his way of eating and chewing, or his way of walking," he describes. And the bad insect? « Polistes gallicus , the European wasp ». She has a very bad memory of her, because she was bitten in a park while walking her daughter in Barcelona and cried in pain. "With her I confirmed at least that I was not allergic to wasp bites," something that can be very dangerous.

According to the criteria of The Trust Project

Know more

  • Science and Health
  • Health
  • Dengue
  • Zika

HEALTHCrimea-Congo, Zika, Chikungunya, Dengue ... This is the exotic virus that stalks us

Health The Board detected one month before the alert a rebound in cases of listeriosis, with 150 affected throughout the country

Research Spanish researchers discover one of the keys to a lymphoma without a cure