单项选择题

By 2003 an estimated 42 million people were infected (47)______ and more than 20 million people had died of AIDS. A United Nations report presented in 2002 (48)______ that unless prevention programs were greatly expanded, AIDS would claim an (49)______ 68 million lives by 2020. Sub-Saharan Africa has been the region hardest hit by the HIV/AIDS pandemic; more than two-thirds of all people with HIV/AIDS are in this region. In the United States, an (50)______ 900,000 people were living with HIV/AIDS in 2002. HIV is spread through contact with (51)______ body fluids such as blood and semen. Infected people may harbor the virus within their bodies for several years or even longer before developing symptoms of AIDS. Though symptomless, they can still infect others. Worldwide, most HIV (52)______ occurs during sexual relations between heterosexual partners. In the United States, the majority of transmission has been between homosexual partners. Transmission among drug addicts who (53)______ infected needles is another significant route of transmission in many countries. No cure for AIDS is known. Researchers are working on preventative AIDS (54)______ , but none are expected to be ready for market in the near future. Meanwhile, drug therapies introduced in the mid-1990’’s have been extremely effective in controlling AIDS (55)______ for some patients. However, the medications are expensive, putting them beyond the reach of the (56)______ majority of the world’’s HIV-positive people. A) estimated I) remarkable B) transmission J) predicted C) novel K) restore D) additional L) commit E) vast M) share F) peculiar N) progression G) infected O) worldwide H) vaccines