Scientific newssheets
417 - AIDS: in Africa, men are less responsive to treatment
November 2012
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.
413 - Malaria: vector mosquitoes are constantly adapting
September 2012
Some develop resistance. Others alter their behaviour. Mosquitoes of the genus Anopheles , the vectors of malaria, always find a way to foil human attempts to protect themselves from this disease. Researchers from the IRD and their partners( 1) have revealed their great capacity for adaptation, which weakens the strategies to combatting their presence, recommended by the WHO. A clinical trial conducted in some thirty or so villages in Benin demonstrated that, the combined use over an 18 month period of mosquito nets impregnated with deltamethrin, and another powerful insecticide in spray form inside the homes, did not lead to a decline in the disease. Neither the number of cases nor the prevalence of the infection( 2) among young children were reduced in comparison with the use of mosquito nets alone. In some localities, the introduction of nets led to a change in the feeding habits of the insects of the Anopheles genus, which usually bite at night time. They are now rife outside dwellings at dawn.
The long-term effectiveness of the current measures to prevent and combat the disease is therefore called into question. Scientists will once again need to innovate if we are to one day eliminate this disease for good.
403 - Bats, a reservoir of resurgent viruses
May 2012
Bats carry numerous diseases that have the potential for resurgence in humans and other animals. A study carried out in collaboration with IRD(
1) researchers and published in Nature communications has revealed the planetary threat they pose. Bats are the source of paramyxoviruses, which cause measles, mumps and numerous respiratory illnesses, some of the primary causes of infant mortality worldwide. These small flying mammals are reputed to have spread these infections throughout the animal kingdom.
Researchers have discovered 60 new types of paramyxovirus. But most importantly, they have recently observed forms of paramyxovirus in bats that are genetically highly similar to forms that were thought to be specific to humans. The existence of such an animal reservoir compromises the quest for eradication of certain human diseases such as measles. Other viruses such as the ravaging Hendra and Nipah viruses, rife in Asia and Australia, have also been observed in latent forms in Africa. Bats need to be placed under a high level of surveillance immediately.
393 - Sleeping sickness under high surveillance
January 2012
Despite the efforts to fight Human African trypanosomiasis (HAT), better known as sleeping sickness, it continues to plague several parts of Africa. This disease, fatal if untreated, is caused by parasites called trypanosomes, which are transmitted to humans by the infamous tsetse fly.
In Western Africa, particularly in the mangroves of Guinea or in the Ivory Coast forests, increasingly close contacts between humans and the vector encourage the transmission and the persistence of the disease. To maximize and target more effectively the difficult and costly fight against the disease, an improved surveillance network has been set up in Africa during the past few years. An IRD( 1) team based at CIRDES( 2) in Burkina Faso – which has now been designated as a WHO Collaborating Centre – has developed a state-of-the-art diagnostic method, the immune trypanolysis test3, which helps identify populations at risk and hence pinpoint priority areas for intervention.
