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416 - Who deforested Central Africa: Man or climate?
November 2012
It is a much debated question: why did Central African forests become partially fragmented between 2,500 and 2,000 years ago, leaving room for more open forest landscapes and savannah? Recently, a publication attempted to explain that it was the farming Bantu peoples who were responsible for this, through the large-scale clearing that they undertook. But several IRD experts and their partners( 1) contest this argument in Science magazine. The fragmentation of the Central African forest was the result of drastic climate change. In fact, during this period a phase of general desiccation spread from the equatorial region right to the edges of the Sahel. Numerous data show that it was only 500 years later, in other words some 2,000 years ago, that Bantu colonisation became widespread. The first Bantu populations therefore merely took advantage of the opening up of the forest to enter these areas and start growing their crops.
374 - Snakebites a public health problem in Africa
May 2011
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.
373 - Increasing rice production using genes from the African species
May 2011
Rice is the world’s most commonly used cereal food, feeding half of humanity. However, rice production will have to double within 20 years from now to meet the needs of a growing population.
Two species are used for cultivation, one Asian and the other African. The Asian species gives much stronger agronomic performances, but the African one is more rustic, more resistant to pathogens, more tolerant to drought and soil salinity.
With the aim of transferring these properties to Asian rice, IRD scientists and their research partners( 1) are seeking to overcome the sterility between the two species( 2). They used genome sequencing to compare the structure of a portion of chromosome, identified as the factor behind the reproductive barrier. These investigations, the first results of which were published recently in the journal PLoS One , have led to the definition of genetic markers allowing more rapid development of fertile lineages of improved Asian rice.
332 - African women reacting against Aids
November 2009
Over 33 million people in the world are living with HIV, the Aids virus, and 75% of them live in Sub-Saharan Africa. Most of the people ill with the disease on that continent are women. In the Ivory Coast, the West African country most affected by the pandemic, two women are contaminated for every one man. Women are indeed physiologically more vulnerable to a sexually transmitted infection like HIV.
However, in spite of this gender inequality in relation to Aids, far more women than men are taking part in treatment programmes. Is it their concern to protect their children and see them grow up? Are programmes better geared to women? IRD researchers and their partners (1) recently found evidence for a “gender paradox” and are seeking to understand this by examining women’s experience with HIV care measures.
Sleeping sickness: tsetse flies counterattack in urban areas
June 2009
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