In 1982, scientists at the Centers for Disease Control and Prevention (CDC) incorrectly inferred that Haitians were at increased risk for acquiring HIV (1), a generalization that resulted in unprecedented national stigmatization. The association was later dropped, but Haiti's economy never recovered. Gilbert et al. (2) again link HIV's origins and Haiti, stating that “subtype B likely moved from Africa to Haiti in or around 1966” and then on to the United States. They base this hypothesis on viral sequences from only five Haitian–Americans with AIDS in 1981 who had arrived in the United States “after 1975.” Without treatment, the average time from seroconversion to AIDS is 5.2 years in Haiti (3); it is thus debatable where and when these patients acquired HIV.

The epidemiology of AIDS in Haiti also refutes the authors' claims. In the early 1980s, the epidemic was predominantly male and urban, suggestive of its origins in sex tourism. The epidemic became generalized within 3 years as men spread the virus to their female partners, to rural areas, and through the blood supply (4, 5). Retrospective testing of Haitian blood samples from the 1970s failed to identify a single case of HIV, and no cases were traced back to the thousands of Haitians paid to donate blood to Americans during that era. Furthermore, skilled clinicians and thousands of autopsies did not identify an AIDS-defining illness in Haiti until 1978 (5, 6).

Haiti has overcome enormous obstacles and mounted one of the world's most successful responses to the AIDS epidemic. Scientists need to carefully consider the great harm that can result from asserting dubious claims of causality.

• © 2008 by The National Academy of Sciences of the USA