Researchers find simian retrovirus transmission to humans is widespread

By Tim Parsons
School of Public Health

People in Central Africa who hunt monkeys and great apes are routinely being infected by retroviruses, the class of viruses that includes HIV. An international team of researchers from Cameroon and the United States has documented, for the first time, the transmission of a retrovirus from primates to people in natural settings.

In the March 20 edition of The Lancet, researchers from the Johns Hopkins Bloomberg School of Public Health, the Cameroon Ministry of Health, the Centers for Disease Control and Prevention and other institutions report the presence of antibodies for simian foamy virus in 1 percent of the people tested. People infected with SFV came from multiple isolated villages and were infected with viruses from at least three separate species of monkey and ape.

"Simian foamy virus should be considered a novel retrovirus of humans. Researchers have documented animal to human transmission of SFV in the laboratory, but our study is the first to demonstrate that these retroviruses are actively crossing into people," said Nathan Wolfe, lead author of the study and an assistant professor in the Department of Epidemiology at the School of Public Health. "The hunting and butchering of primates plays a role in retroviral emergence. It is in all of our interests to put into place economic alternatives to help people move away from hunting and eating these animals. In addition to preserving endangered species, such development efforts will reduce the risk that ongoing cross-species transmission of retroviruses and other pathogens could spark future epidemics similar to HIV," Wolfe said.

For the study, Wolfe and his colleagues examined blood samples from 1,099 individuals from Cameroon who were taking part in an HIV prevention program. All the study participants reported having some exposure to nonhuman primate blood, which occurred primarily through hunting and butchering.

The blood samples were screened for SFV antibodies, which were detected in 10 of the samples. Individuals were identified as being infected with viruses from three different primate species, which included De Brazza's guenon, mandrill and gorilla. De Brazza's and mandrill are also naturally infected with simian immunodeficiency viruses, or SIVs, the same class of viruses from which HIV originated. It is not known if SFV is harmful to humans or whether it can be transferred from person to person or through blood transfusions. Further research on these questions is ongoing.

"The SFV infections in this study were from several geographically isolated locations. This suggests that, contrary to conventional wisdom, retroviral zoonosis is widespread and arising from various locations where people are naturally exposed to mandrills, gorillas and other monkeys and apes," said Donald S. Burke, co-author of the study and a professor of international health and epidemiology at the School of Public Health.

Other authors of the study are Nathan D. Wolfe, William M. Switzer, Jean K. Carr, Vinod B. Bhullar, Vedapuri Shanmugam, Ubald Tamoufe, A. Tassy Prosser, Judith N. Torimiro, Anthony Wright, Eitel Mpoudi-Ngole, Francine E. McCutchan, Deborah L. Brix, Thomas M. Folks, Donald S. Burke and Walid Heneine. The research was funded by grants from the U.S. Military HIV Research Program, the National Institutes of Health's Fogarty International Center and the Johns Hopkins Bloomberg School of Public Health's Center for a Livable Future.

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