Background:  The recognition that AIDS originated from nonhuman primates (NHP) heightens concerns associated with transmission of simian retroviruses to humans. Although recent studies document frequent infection with simian foamy virus (SFV) among primate hunters in Cameroon and primate handlers in North America, little is known about the spread and geographic distribution of SFV outside these populations.

Methods:  We tested 180 plasma samples collected from sex workers (n = 97) in 1985, and sex workers (n = 42) and tuberculosis (TB) and sexually transmitted disease (STD) patients (n = 41) in 1999 to 2000 all from Kinshasa, Democratic Republic of Congo, and 179 plasma samples collected recently from anonymous blood donors from Yaounde, Cameroon. Plasma samples were screened for SFV antibodies by ELISA and reactive specimens were tested further by a Western blot (WB) assay that can detect monkey- and ape-type SFV reactivity. Polymerase chain reaction (PCR) amplification of DNA from peripheral blood lymphocytes (PBL) and phylogenetic analysis was used to define the NHP species origin of SFV.

Results:  One of 139 (0.72%) sex workers was SFV WB positive. This specimen was collected in 1985 from an HIV-1-infected person. One of 179 (0.56%) of Cameroonian blood donors was also SFV WB-positive and HIV-1 positive. An SFV integrase sequence was amplified from the PBL DNA of the SFV-positive blood donor. Phylogenetic analysis showed SFV infection originating from a mandrill, a NHP species that is frequently hunted and consumed in Cameroon.

Conclusions:  Our study documents SFV infection among different Central African populations. The finding of SFV in samples collected recently and in 1985 from blood donors and sex workers suggests long-standing infection and opportunities for blood-borne and sexual transmission. The observed co-infection with SFV and HIV heightens the importance of defining the clinical and public health consequences of these infections.

Keywords: simian foamy virus; simian retroviruses; zoonosis