New genetic evidence shows that people were first infected with the HIV virus around the beginning of the 20th century, and researchers say the virus was able to take hold in human populations because of the growth of colonial cities in sub-Saharan Africa at that time. The evidence comes from a newly discovered tissue sample taken in 1960 from an HIV-infected woman who lived in Leopoldville–the city now known as Kinshasa, the capital of the Democratic Republic of the Congo.
Lead researcher Michael Worobey says that the virus may have crossed over from chimpanzees to rural humans repeatedly in the timeframe he identified, from 1884 to 1924; however, it didn’t take off in human populations until people in sub-Saharan Africa crowded together in cities. When the team looked at the region’s political history, they were struck by parallels between HIV’s spread and population expansion. The first major cities – Kinshasa, Douala, Brazzaville, Yaounde, Bangui – were founded by European colonialists in the late 1800s. Their populations started booming around 1910. “I was stunned by the timing,” says Worobey. “I would bet that cities, and the high-risk [sexual] behaviours found in them, are necessary to allow one of these sporadic viral jumps to get a toehold in the human population” [New Scientist].
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Tiny parasitic worms that cause chronic illness in millions of sub-Saharan Africans may increase their chances of contracting HIV, according to a new report. This study comes just a week after another set of researchers announced a different theory regarding a factor that could increase Africans’ susceptibility to the HIV virus, hypothesizing that a genetic variant found in people of African descent raises the risk of HIV infection.
In the latest study, researchers infected monkeys with the worms that cause schistosomiasis, and then injected them with a form of the HIV virus. They found that much lower amounts of the virus were necessary to give AIDS to the monkeys that had the parasitic worms, as compared to parasite-free monkeys. The phenomenon… needs to be verified in humans. But with primates a generally reliable model of AIDS pathology, it could help explain why sub-Saharan Africa, where 160 million people are infected with schistosomiasis, has 10% of the world’s population and 62% of its AIDS cases [Wired News].
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In a sign of the slow progress in the medical fight against the HIV virus and AIDS, a federal health agency has canceled plans for an ambitious clinical trial of an experimental HIV vaccine. Although this candidate vaccine was once thought very promising, researchers lost confidence in it after the failure last September of a similar candidate from drugmaker Merck & Co. that may have left some volunteers more vulnerable to HIV infection [San Francisco Chronicle].
Researchers at the National Institute of Allergy and Infectious Diseases had hoped to begin enrolling 8,500 volunteers in the vaccine trial last fall, but the trial was postponed after the Merck vaccine was shown to be failing in its two main objectives: to prevent infection and to lower the amount of H.I.V. in the blood among those who became infected…. After a safety monitoring committee detected the problems with the Merck vaccine in September, the company quickly halted its study [The New York Times].
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It’s a mind-boggling piece of medical news: A genetic variant that’s commonly found in people of African descent raises the risk of HIV infection by about 40 percent, but also causes HIV-infected people to live longer. Researchers say the trait is extremely common because it used to have a beneficial effect; it protected people against a form of malaria that is now fairly rare.
The genetic variant may partially account for the high HIV rates in sub-Saharan Africa, where over 24 million people are currently living with the disease. While the differences in HIV prevalence in different parts of the world can be partly explained by different social conditions and sexual behaviour, scientists have long suspected that there may be genetic reasons why the virus is rife in certain communities [BBC News].
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When an experiment finds out that a treatment doesn’t work as expected and that a cherished hypothesis just isn’t right, it’s not considered as newsworthy as an amazingly effective treatment that sparkles with potential. But the negative findings are just as important in their contributions to medical knowledge.
In that category, a new study dismisses the theory that treating herpes reduces patients’ risk of HIV infection, a strategy that was believed to hold promise. Researchers wrote in a commentary: It is time to reassess the hypothesis and to adjust prevention policy accordingly [The Lancet, subscription required].
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Almost 3 million AIDS patients in developing nations are now receiving treatment from the life-extending antiviral drugs, according to a new report. It sounds like good news, until you realize that the World Health Organization (WHO) had hoped to reach that milestone in 2005.
AIDS advocates say the international community was slow to commit to the monumental task of providing drugs to rural patients around the world, many of whom don’t even know that they’re infected. But in the past few years, boosted by the Bush administration’s five-year, $15 billion AIDS program and an organized international effort, the project began to have effect.
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