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Female tiger mosquitoes, vectors of the chikungunya virus and of dengue fever, had been thought to mate only once during their short few weeks of life. They are apparently much less faithful than imagined, however. A team representing the IRD and its partners( 1) has discovered that they may in fact mate with several males during their short lives. What is more, the same clutch of eggs can be engendered by different fathers! For their part, the males can mate with over 10 different females.
These recent studies, conducted on the island of Reunion and published notably in the journal PLOS ONE , will make it possible to perfect the "sterile insect technique". This innovative approach to fighting against vectors of disease consists of fooling females into mating with infertile males so as to reduce the population of mosquitoes in the wild. Researchers will, in particular, be able to establish what quantity of sterilised males to release in order to compensate for the infidelities of the females.
Dengue fever and the chikungunya virus continue to take their toll all over the world. In the absence of either a vaccine or effective treatment, attacking the vector remains the sole course of action. If this new method proves promising, it will offer an ecologically acceptable alternative to the use of insecticides.
Dengue fever, transmitted by the Aedes mosquito, affects hundreds of millions of people in around one hundred tropical countries and causes 25 000 deaths per year. In the absence of a vaccine, determining the factors that influence epidemics to predict them better is a real public health challenge. One scientific study, conducted in New Caledonia, demonstrates the essential role of the local climate in epidemic dynamics. IRD researchers and their New Caledonian colleagues( 1) analysed epidemiological and climatological data gathered in Noumea over forty years. They highlighted the correlation between specific weather conditions and dengue fever outbreaks.
This work enabled statistical models to be drawn up explaining and predicting viral episodes. The Caledonian public health authorities have already integrated these tools into their decision-making strategies and a similar approach in other South Pacific countries is being developed, with a new collaborative regional programme.
Public health policies have addressed the problem of mother-to-child HIV transmission in Thailand. However, a large number of children who were born with the virus that causes Aids are now reaching adolescence, a critical period when their survival is at risk. As part of their work on the treatment of HIV, a team from the IRD and their partners( 1) have followed these children as they grow up. To explain the treatment failures observed and to understand how to help these children, the team has carried out a nationwide survey in Thailand named TEEWA( 2) among adolescents aged between 12 and 19 years, born with HIV. The burden of treatment, the side-effects of the illness, difficulties in dealing with sexuality, and the fear of stigmatisation, etc. are all obstacles that may cause these youngsters to stop their medication. The study highlights the need for research to simplify treatment and points up the importance of combating prejudice through specific support and awareness campaigns.