The
Languedoc-Rousillon historyWhether the mosquito is simply a nuisance, as on the French Mediterranean coast, or a vector of serious diseases, such as in tropical countries, it has always been a target for Man.
The
Languedoc-Rousillon history
Mosquitoes
do not transmit Aids
The Languedoc-Roussillon history
We only have to recall the severe yellow fever epidemics or the almost world-wide malaria epidemic that occurred until the start of the 20th century.
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The lagoon region now covered by EID Méditerranée was also afflicted. In 1868, a study was carried out by the Hérault highways department. It showed that the average life expectancy in some of the Hérault's coastal areas was about 20 years, whereas for France as a whole it was 37 years! This area was considered a "region of fever" until the end of the 1940s. Indeed several epidemics had been known, for example, those that occurred during the Middle Ages in Narbonne (Aude), Agde (Hérault), Maguelonne (Hérault) and Aigues-Mortes (Gard). These outbreaks of fever reached epidemic proportions in different coastal areas of Languedoc-Roussillon until the dawn of the 20th century. |
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There was a series of epidemics during World War I, the worst of which was in 1917, when 158 cases of paludism were recorded in the Montpellier region (Hérault). This coincided with the hospitalization of the wounded and sick from the Army in the Orient. Until 1939, minor outbreaks occurred in Mauguio and Carnon (Hérault) and Grau-du-Roi (Gard). In the same year, a serious epidemic broke out in Barcarès, Saint-Cyprien and Argelès-sur-mer (Pyrénées-Orientales). This occurred after the exodus of Spanish refugees during the civil war. |
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Finally, in 1942 and 1943, a new epidemic wave was recorded in Camargue and Petite-Camargue (more than 200 cases). This was linked to the arrival of the Africa Corps from eastern Libya and Tunisia Several isolated cases were reported later that could not be linked to a particular cause and the disease has since disappeared. Even though paludism has been eradicated in this region, other human and animal diseases transmitted by mosquitoes have been discovered. They do not endanger the inhabitants of Languedoc and, therefore, no specific operation has been mounted to control them. Now, it is the economic developments such as tourism, industry or agriculture that justify control. |
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It is a disease caused by a protozoan, a single-celled organism called haematozoan. This parasite is transmitted from man to man through biting by mosquitoes from the genus Anopheles which are host to the haematozoan during the first part of its lifecycle. It completes the second part of its lifecycle in Man. The disease is found all over the world and affects more than half a billion individuals. For years, it was rife in temperate countries such as France, but it practically disappeared in Europe 50 years ago. However, it still affects many people living in subtropical parts of Africa, Asia and America. At first, treatment and prevention were carried out with an alkaloid extract of cinchona: quinine. Synthetic anti-malaria products are now used. There is still no vaccine.
It is caused by a virus transmitted from man to man through biting by a mosquito from the genus Aedes. It was first recorded when regular contact was established between Europe and the subtropical coasts of America and Africa. It is less widespread than paludism and is found mainly in the subtropical regions of Africa and America. It has never been reported in Asia. In Europe, only a few isolated cases in ports have been reported. It is extremely serious and there is no specific treatment. Effective vaccines have been developed. |
It is a viral disease that is generally mild but its haemorragic form can be fatal. It is transmitted from man to man by a mosquito from the genus Aedes. It is found particularly in Southeast Asia, the South Pacific, the Indian Ocean, Australia and the Caribbean. There is no medical treatment and no vaccine for this disease. |
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Filariasis or elephantiasis |
It is caused by a worm that spends part of its lifecycle in mosquitoes from the genus Culex and then develops in man. It results in debilitating and sometimes extraordinary swellings. It is found in Asia, Africa, the Pacific and Australia.
Diseases local to Languedoc illon that afflict humans and animals:
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- "lourdige", a serious encephalitis that affects horses, is caused by the West-Nile virus carried by a mosquito from the genus Culex. This virus can also cause a very mild form of flu in Man. |
- the Tahyna virus, transmitted by a mosquito from the genus Ochlerotatus, causes mild flu-like symptoms in Man.
| - myxomatosis, a disease of rabbits, is caused by a virus transmitted by several species of mosquito belonging to the genera Ochlerotatus and Anopheles although the main vector is a flea that infests the burrows. |  |
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- canine filariasis is caused by a worm. Mosquitoes inject the worm larvae which attach themselves to the heart wall to complete their development. This disrupts the blood circulation and can lead to the dog's death. |
Mosquitoes do not transmit aids
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RETROVIRUS Acquired immune deficiency syndrome, or Aids, is not strictly speaking a disease. It is characterized by recurrent and stubborn infections, so-called opportunist infections, that become serious in the case of Aids sufferers whose immune system collapses. It is caused by a virus belonging to a rare group of retrovirus discovered in 1983 by Luc Montagnier (Institut Pasteur, Paris). The only proven modes of transmission are through blood and sperm: blood transfusions, injections, homo- and heterosexual intercourse. The role of other organic liquids (tears or saliva) has never been demonstrated. The role of insects, mosquitoes in particular, which was talked about at the start of the epidemic, has now been shown to be non-existent. |
Au cours des rencontres avec le public, une question est très souvent posée : le moustique peut-il transmettre le sida? La réponse est non, ainsi que l'expliquent ci-dessous Gilbert Sinègre, directeur technique et scientifique honoraire de l'EID Méditerranée, et le docteur Jean Cousserans, médecin parasitologue, secrétaire du Conseil scientifique de l’EID Méditerranée.
The mosquito's role as a vector is largely due to its capacity to bite different hosts several times, which enable it to complete several gonadotrophic cycles (egg development in the reproductive organs) and, therefore, lay more than once. In areas where mosquitoes are endemic, an epidemiologist can determine the risk to human populations from the physiological age, the number of breeding females in a population of mosquito vectors, and the number of lays. The cycle of parasites that generate serious diseases, such as paludism, involves a reservoir of parasites (usually a human with paludism), a vector such as the Anopheles mosquito, and a susceptible host, for example a healthy human who, once they have been bitten, is infected by the parasite and contracts the disease. Several conditions are necessary for the completion of this cycle:
- when bitten, the disease in the contaminated host (the reservoir) should be at a specific stage of development, for example, there needs to be a large number of parasites in the host's blood, which only occurs at precise moments in the parasite's cycle.
- the parasite (protozoan or virus) also has to complete a particular cycle in the vector's body. It should be capable of protecting itself from the destructive action of the vector's digestive enzymes, before it passes through the stomach wall into its body cavity to multiply and finally move into the biting insect's saliva glands.
- the healthy host should be susceptible to the parasite, in other words, should not be resistant to the disease.
When all these conditions have been met, the cycle is as follows: the female mosquito bites an individual with paludism and, in order to do this, first injects its urticating saliva which is free of parasites. She absorbs the infected blood. The parasite (plasmodium in the case of paludism) passes into the saliva glands after modification. The female feeds again, before or after laying, on a healthy and susceptible individual. She injects her parasite infested saliva and contaminates the healthy individual.Mosquitoes do not transmit AIDS.
People might think that the aids virus could be transmitted by the infected bite of a mosquito either through its saliva, by phoresy (passive transport) on the mouth parts, or by squashing a mosquito that has just fed on an aids carrier.
It has been proven that the aids virus is digested in less than 24 hours by the stomach enzymes in mosquitoes and completely destroyed. There is, therefore, no chance of the virus passing from the stomach into the general cavity and then to the saliva glands. Phoresy is impossible because the viral load is too small. In fact, an aids carrier only has a very small amount, about 10 units, of the virus (HIV) in their blood. It has been calculated that if there were 1 000 units, the probability of injecting a single unit by phoresy would be 1:10 million. In other words, 10 million mosquitoes biting 10 million aids carriers need to bite a healthy individual at the same time, ie interrupt their feed on an aids carrier and bite the same host immediately! Outside the organism, blood, or sperm, the virus is not viable for very long. Therefore in practice, it is quite clear that contamination by phoresy is impossible. The same goes for squashing a mosquito, because its blood is not injected into the organism nor does it carry a sufficient viral load. The virus is also destroyed quickly when exposed to air. Transmission by "syringe" is also impossible because saliva canals and alimentary canals differ.
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