RESEARCH Simian Foamy Virus Transmission from Apes to Humans, Rural Cameroon Sara Calattini,* Edouard Betsem A. Betsem,† Alain Froment,‡ Philippe Mauclère,*†‡§ Patricia Tortevoye,* Christine Schmitt,* Richard Njouom,§ Ali Saib,¶ and Antoine Gessain* Simian virus infections of humans are an increasing highly prevalent in several animal species in which they public health concern. Simian foamy virus (SFV) infections cause persistent infections (16–26). Phylogenetic analyses have been reported in persons occupationally exposed to have demonstrated a species-specifi c distribution of such nonhuman primates and in a few hunters in Cameroon. To retroviruses. This species specifi city indicates a long-term better understand this retroviral zoonosis in natural settings, coevolution of SFVs with their natural hosts (27), which we studied persons who lived in southern Cameroon, near could explain their possible lack of pathogenicity observed nonhuman primate habitats. First we studied a general popu- lation of 1,164 adults; 4 were SFV positive according to se- in vivo and the persistence of the infection (23,24,28–31). rologic and molecular assays. Then we studied 85 persons Among nonhuman primate populations, SFV seropreva- who reported having been bitten or scratched by nonhuman lence can reach 75%–100% in adults, and SFVs appear to primates; 7/29 (24.1%) of those who had contact with apes be present at high concentrations in the saliva of infected (gorillas or chimpanzees) were SFV positive, compared with animals (16–18,22,29,31). only 2/56 (3.6%) of those who had had contact with monkeys. In humans, SFV infection has been reported in 1%–4% These data demonstrate effi cient transmission of SFVs to hu- of persons occupationally exposed to nonhuman primates mans in natural settings in central Africa, specifi cally follow- in zoos, primate centers, and laboratories, mainly in North ing ape bites, and viral persistence in the human host. America but also in Europe (7–10). More recently, natu- rally acquired SFV infections were described in a few hunt- large proportion of viral pathogens that have recently ers living in Cameroon (11) and in 1 person who had had A emerged in humans have originated in various ani- contact with Macaca fascicularis in Indonesia (32). mals. After initial interspecies transmission, these viruses After other studies demonstrated high prevalence and have evolved and disseminated into the human population genetic diversity of SFVs in monkeys and apes in Ga- through various distinct mechanisms. However, under- bon and Cameroon (16,17), we investigated the presence standing of the initial steps of the emergence of some vi- of SFV infection in humans living in these regions. Our ruses and associated diseases remains poor. Microbiologic goals were to 1) determine, by using specifi c serologic studies of these high-risk populations are thus necessary to and molecular methods, the prevalence of SFV infection obtain new insights into the early events of this emergence in the adult population of different ethnic groups (includ- process (1–4). ing Pygmies) who lived in rural areas of Cameroon near Nonhuman primates represent a potential source of mi- natural nonhuman primate habitats and who were thus at crobes for humans (1,5–12), e.g., simian immunodefi ciency risk for cross-species transmission; 2) trace the origin of virus and simian T-cell lymphotropic virus (12–15). Simian the SFVs infecting these persons by isolation and molecu- foamy viruses (SFVs) are exogenous complex retroviruses, lar characterization of the virus; and 3) gain new insights into the epidemiologic determinants and risk factors linked *Institut Pasteur, Paris, France; †Université de Yaoundé I, Yaoundé, to such naturally acquired retroviral infections, especially Cameroun; ‡Centre de l’Institut de Recherche pour le Développe- the type of nonhuman primates, the circumstances of the ment, Orléans, France; §Centre Pasteur du Cameroun, Yaoundé, contact leading to the infection, and possible intrafamilial Cameroun; and ¶Hôpital Saint Louis, Paris, France transmission of such viruses. 1314 Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 13, No. 9, September 2007 Simian Foamy Virus Transmission from Apes to Humans Materials and Methods described (18,22,26). Plasma was tested at a 1:100 dilution. For each Whatman sample, a 1-cm punch was diluted in 1 Populations mL of phosphate-buffered saline and tested at a 1:8 dilution The fi rst study, a retrospective study, was based on (online Technical Appendix). Virus isolation, electron mi- a large series of samples collected during 1994–2000 for croscopy, and immunofl uorescence (IFA) were performed epidemiologic studies on human T-lymphotropic virus as described (9,21,26,36; online Technical Appendix). (HTLV)-1 and HTLV-2 as well as human herpesvirus 8 For the molecular studies, genomic DNA was ex- (33,34). The samples originated from adults of 3 ethnic tracted from the peripheral blood buffy coat by using the populations: Bakola Pygmies and 2 groups of Bantus, QIAamp DNA Blood Mini Kit (QIAGEN, Courtaboeuf, who lived in lowland tropical remote forest areas (Bipindi/ France). Two SFV proviral genomic regions (465 bp of Lolodorf and Ntem) in southwestern Cameroon (Figure 1). the integrase gene and 109 bp of the long terminal repeat The second study, the hunter study, was conducted [LTR]) were amplifi ed in nested PCR (18,21,37). Integrase in 2004–2005 in remote villages near nonhuman primate PCR products were purifi ed, cloned, and sequenced. The habitats in the South Province of Cameroon (Figure 1). GenBank accession numbers of the 13 new integrase se- This study was focused on persons who reported direct and quences are DQ838495–DQ838507. Phylogenetic analyses often severe contacts (bites, wounds, scratches, other inju- were performed as described (18,38,39; online Technical ries) with animals, especially nonhuman primates, mainly Appendix.) while hunting. Both studies received clearance from national and local Results authorities. All participants received detailed information about the study and gave consent. Blood samples were col- Retrospective Study lected in 5–10 mL EDTA tubes. Plasma was available from The retrospective epidemiologic survey was performed all participants in the retrospective study, whereas for some among 1,164 adults (mean age 50.6 years) who lived in the in the hunter study, only a few drops of blood were taken Ocean region of Cameroon (Figure 1; Table 1). The studied by fi ngerstick and conserved on fi lter paper (Whatman populations included 478 Bakola Pygmies (mean age 47.6 samples) as described (35). See online Technical Appen- years) and 686 Bantus (mean age 52.6 years). dix, available from www.cdc.gov/EID/content/13/9/1314- Of the 1,164 samples tested by WB assay based on Techapp.pdf, for more details. chimpanzee foamy virus antigens, 21 (1.8%) were consid- ered clearly positive (strong reactivity to both p70 and p74 Serologic Tests, Virus Isolation, and Molecular Studies ape proteins, Gag doublet) (Figure 2, panel A), 86 (7.4%) We screened by Western blot (WB) all plasma and were considered borderline/indeterminate (presence of ei- Whatman samples for the presence of SFV antibodies as ther a faint gag doublet or of at least a strong band of the right size and 1 or few other bands of often low intensity) (Figure 2, panel C), and the remaining 1,057 samples were considered negative (absence of any band) (Figure 2, panel C; Table 1). The 86 indeterminate samples were then tested by WB assay using antigens from a monkey foamy virus (originating from participant AG16, Figure 2, panel B); all were still indeterminate or negative. DNA was available from 11 of the 21 persons whose WB assay results were positive and from 52 of 86 whose results were borderline/indeterminate. All 63 DNA sam- ples were amplifi able by PCR for β-globin gene. When in- tegrase primers were used, PCR was positive for 4 of 63 samples (Table 2). When LTR primers were used, PCR was positive in 3 of these 4 samples (Table 2). Field interviews indicated that 3 persons (2 Bakola Pyg- mies [801001 and 210301] and 1 Bantu [60601]) were fre- Figure 1. Geographic distribution in Cameroon of the studied quent hunters and had been severely bitten by gorillas 25–35 populations and the 13 persons infected by simian foamy virus years ago (Table 2); all 3 had scars on their legs and fi ngers (SFV), according to serologic and molecular results. Red, SFV- (Figure 3). The fourth infected person (A051302) was a Ban- positive persons from the hunter study; green, SFV-positive persons from the retrospective study; blue circle, Pygmy area; violet circles, tu woman who did not recall any bites or injuries from mon- Bantu areas. keys or apes. However, she had had frequent contact with Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 13, No. 9, September 2007 1315 RESEARCH Table 1. Serologic results for simian foamy virus retrospective study, rural Cameroon, 1994–2000 Study population Test results Borderline, Positive, Area Ethnicity Age range, y Total no. Men Women Negative no. (%) no. (%) Bipindi Lolodorf Bakola 30–82 478 214 264 448 16 (3.34) 14 (2.92) Pygmies Bantus 40–83 370 180 190 326 40 (10.81) 4 (1.08) Ntem Bantus 20–78 316 144 172 283 30 (9.49) 3 (0.9) Total 20–83 1,164 538 626 1,057 86 (7.38) 21 (1.8) wild game meat from nonhuman primates while butchering asked for persons who had had direct contact and severe and preparing meals, as is common in this area (3,4). bites, scratches, wounds, other injuries from animals, main- Sequence analyses of the 4 integrase gene fragments ly nonhuman primates. indicated that the 3 persons bitten by gorillas were infected This study included 102 persons, 84 men and 18 wom- with a gorilla foamy virus.