The viruses, which have been named Human T-lymphotropic Virus types 3 and 4 (HTLV-3 and HTLV-4), belong to a genus of viruses known to spread and cause serious illness in humans. The researchers believe the findings demonstrate the need to regularly survey those human populations known to be in contact with animals for new infectious diseases emerging from animals. The study, which was first reported at the 12th Conference on Retroviruses and Opportunistic Infections, is now published in the May 16, 2005, Online Early edition of the Proceedings of the National Academy of Sciences.
"The emergence of HIV from primate origins has cost millions of lives and billions of dollars. The discoveries of HTLV-3 and HTLV-4 show that, far from being rare events, retroviruses are actively crossing into human populations," said the study’s lead author Nathan Wolfe, ScD, assistant professor in the Department of Epidemiology at the Bloomberg School of Public Health.
The research team collected and examined blood samples from more than 900 people living throughout Cameroon. All the individuals studied reported some exposure to blood and body fluids of nonhuman primates, contact mostly due to hunting and butchering of bushmeat, and in some cases to keeping primates as pets. An analysis of the blood samples determined that multiple simian viruses had crossed over from primates to infect the study participants. In two hunters, the researchers identified HTLV-3 and HTLV-4, the two previously unknown viruses.