A small study from the world's first mass immunization campaign against cholera (search) suggests that the vaccine may work in people with the AIDS (search) virus — a finding that could prove useful in Africa, where HIV is rampant, researchers say.

Cholera is a major killer in developing countries, where it is spread mainly through contaminated food or water. The bacterium attacks the intestine and causes severe diarrhea and dehydration.

An oral vaccine has shown promise against cholera, but it has been unclear whether it would work in people whose immune systems were weakened by HIV.

Researchers tested the vaccine in 2003-04 in the port city of Beira in Mozambique, where an estimated 20 percent to 30 percent of the population has the AIDS virus. More than 14,000 residents got the vaccine. Soon afterward, cholera broke out.

International researchers examined 43 people with confirmed cases of cholera and 172 others who did not get sick and concluded that the vaccine offered 78 percent protection against cholera. That is comparable to the 85 percent rate reported in vaccine trials in Bangladesh and Peru, which have far lower HIV rates.

From that, the researchers inferred that the vaccine was effective in people with the AIDS virus. The researchers did not actually test people to see if they had HIV.

The study was funded by the Bill and Melinda Gates Foundation (search). The findings appear in Thursday's New England Journal of Medicine.

In an accompanying editorial, Dr. Jeffrey Drazen, editor in chief of the journal, noted that victims of the devastating tsunami in Southeast Asia could benefit from the cholera vaccine if a major outbreak were to occur.