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In Africa, more than 25 million people, most of them women, are currently infected by the AIDS virus. However, a study conducted by Epicentre( 1) and IRD researchers shows that men are less responsive to treatment. The provision of healthcare is intended to restore the level of lymphocyte cells, called T-CD4, reduced by HIV. Based on 13,000 patients monitored through four programmes carried out by Médecins sans frontières France in Malawi, Uganda and Kenya, the study shows that the reconstitution of these white blood cells is slower in men than in women.
Due to stigmatisation and work- and transport-related constraints, among others, men often receive healthcare at a later stage and are less responsive to treatment. However, this gender-based difference could also stem from biological causes, such as physiologically lower rates of T-CD4 lymphocytes.
This study underlines the fact that men should therefore receive special attention from programmes aimed at fighting the disease.
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.
One and a half million people per year are poisoned by snake venom in Sub-Saharan Africa. An IRD researcher recently analysed around 100 surveys and medical reports published over the past 40 years. No large-scale study of the situation had hitherto been conducted and public health authorities had underestimated the size of the problem. This means that currently only 10% of victims are treated, owing to a shortage of antivenoms * and lack of awareness among health care practitioners. Yet the clinical complications can be very serious, even fatal. A bite from a cobra or mamba can bring on death by asphyxia –due to respiratory paralysis– within 6h after the incident. Venom injected by the ocellated carpet viper, common in the African savannah, can cause haemorrhages leading to the victim’s death in a few days.
This new study provides authorities with more detailed and reliable figures which should enable them to readjust their health-care services in better tune with needs.
The absence of malaria in the Seychelles is rather a mystery. Areas of the world which are spared from the disease are rare and for the African region the archipelago is an exception. All the conditions favourable for anopheline mosquitoes, the malaria vectors, seem to be there: climate, location, high volumes of air and maritime traffic. An IRD researcher and his partners( 1) recently made the first demonstration that this absence of endemic Anopheles stems from that of native terrestrial mammals. Livestock, dogs, cats, mice and so on did not arrive until the end of the 18th Century, accompanying humans. This study concludes that the mosquito feeds exclusively on blood of terrestrial mammals, not on that of birds, reptiles or bats, even by default.
However, since Man set foot on the Seychelles, the vector could have colonized the archipelago. Although these islands have been preserved from the ravages of malaria, notably thanks to preventive health control measures at the points of entry, the researchers urge the Seychelles authorities to persist with their efforts.
Every day, 1500 young infants in the world contract HIV from their mother. Ninety per cent of them live in Sub-Saharan Africa. Infection occurs in utero or during delivery, or later during breastfeeding. Young mothers could abandon breastfeeding, but this would deprive their baby of an essential source of nutrients and antibodies and, if artificial milk was used, expose the child to other illnesses (such as diarrhoea owing to lack of safe drinking water, or malnutrition).
Now they can breastfeed with less risk. An international consortium of researchers, including a team from the IRD( 1), recently showed that by taking an antiretroviral treatment up to the sixth month of breastfeeding mothers can halve the probability of contaminating their child in comparison with standard treatment recommended in the previous WHO (World Health Organization) protocol guidelines( 2). This new approach reduces the risk of HIV transmission from 9.5 to 5.4%. These highly encouraging results prompted WHO to revise their guidelines on prophylaxis during breastfeeding.