In Montpellier, a first case of human infection with the Usutu virus transmitted by a mosquito was diagnosed. This tropical virus had never been observed in France. Transmitted by an ordinary mosquito, it testifies to the increase in France of the risk of emerging infectious diseases, in parallel with climate change.
After dengue fever, the Usutu virus strikes in France. Transmitted by the bite of an ordinary mosquito, Culex, this new virus in our country attacks the nervous system. Normally tropical virus of African origin (Senegal, Nigeria, Uganda, Burkina Faso, Ivory Coast, Morocco …), the Usutu mainly affects themigratory birds.
His arrival in France testifies to a worrying phenomenon, the acclimatization in our country of viruses, bacteria and parasites of tropical origin, in parallel with global warming. A phenomenon which does not concern only France and which worries the experts.
The climate risk worries doctors
Doctors have observed the spread of infectious diseases of tropical origin for several years in countries where they did not previously exist. This was the case with the West Nile virus which took root in the New York subway several years ago. In Brazil, the yellow fever virus left the Amazon rainforest and is at the gates of large cities (Sao Paulo, Rio de Janeiro) … where no one is vaccinated.
Dengue has already been contracted in the south of France and the tiger mosquito, which can innoculate Dengue and Chikungunya, is believed to move northwards by one department each year. Leishmaniasis is striking more and more humans in the south of France. Finally, there is the question of the impact of global warming on the gradual increase in the frequency of Lyme disease in France.
Scientists from the High Council of Public Health are monitoring these phenomena to better anticipate the epidemics that are likely to occur in the coming years and reports are piling up year after year. All are concordant : “climate change is a bit like death, we know it’s going to happen, but nobody believes it”.
A first case of human infection in France
The first case of human infection in France with the Usutu virus was spotted in Montpellier. 39 year old man would indeed have been infected in 2016 after a Culex-type mosquito was infected by migrating birds from Africa. It took a year and a half before having the exact diagnosis.
The man came to consult for a facial paralysis, but with a rather atypical clinical picture: ants in all the right half-body and small associated motor deficits. Several human cases have been identified in Europe: 10 in Italy and three in Croatia. This “emerging” virus in our country remains poorly understood and INSERM has therefore launched an investigation to find out more about this cousin of the Zika virus.
An essentially animal virus
The development cycle of the Usutu virus is still unknown to the scientific community, but it seems that migratory birds and some raptors are the reservoir of the virus. Formally identified for the first time in South Africa in 1959, in Swaziland near the Usutu River (hence its name), the virus has been circulating in Occitanie since 2015.
It is believed to be the cause of several infectious outbreaks causing significant peaks in bird mortality, as in 2004 in Austria. Since 1996, several phenomena of massive bird mortality have been attributed to Usutu in the Italian provinces of Florence and Pistoia, as well as in Hungary, Switzerland, Spain and even Germany. Positive point: the virus is not transmitted from man to man.
You read / heard it in some media. We tell you all about virus detection #Usutu in a patient by researchers @Inserm https://t.co/4QbNDTyEbS and we give you the scientific reference pic.twitter.com/8z3P9VjH9M
– Inserm (@Inserm) June 15, 2018
How to recognize the Culex mosquito?
The Culex mosquito is the most predominant insect in France. Also nicknamed “domestic mosquito”, it can transmit serious diseases such as West Nile Fever or Japanese Encephalitis … as well as the Usutu virus, unlike the anopheles mosquito, vector of malaria or the Aedes mosquito (which makes part the tiger mosquito) which is itself a vector of dengue, Chikungunya and Zika.
Like the tiger mosquito, the Culex appreciates rather warm and stagnant water and / or shady intraforest ponds or ditches and it is capable of biting in the middle of the day (unlike the Anopheles which only bites at night). It is therefore necessary to protect yourself in theory 24 hours a day, hence the interest of eliminating the breeding sites around the houses., that is to say the slightest source of stagnant water, such as the bottom of gutters or even the saucers in flower pots where females like to lay their eggs.
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