THE Bill and Melinda Gates Foundation and the transnational pharmaceutical corporation Merck have announced a 100-million-dollar grant to fight Aids in Botswana. The donation will fund a program in co-operation with the Botswana government aimed at prevention, management and treatment of the disease. Botswana has one of the highest rates of Aids in the world, with one out of every three adults HIV-positive or living with full-blown Aids. The foundation established by Microsoft chairman Bill Gates and his wife will donate 50 million dollars to the project over the next five years. That will be matched by another 50 million dollars from Merck and The Merck Company Foundation, which will manage the program and buy Merck’s antiretroviral medicines for it. The Gates Foundation, which has a 22-billion-dollar endowment, has previously provided grants for the fight against polio, Aids, malaria and tuberculosis.