RESEARCH Figure 1. Western blot analysis of human serum samples for evi- dence of simian foamy virus (SFV) antibodies. Antibodies to the gag precursor proteins (p70/p74) were apparent from the human BH66 blood sample, which indicated infection with SFV. Positive control is an SFV-infected baboon. numbers of persons exposed to primates at monkey temples is necessary to estimate the risk of SFV infection in this context. Monkey Temples in Bali as Contexts for Primate-Human Contact Human and macaque sympatry in Southeast Asia dates back as far as 25,000 years, as evidenced by remains at Niah Cave in Borneo (37). Hindu and Buddhist temples are a relatively recent addition to the landscape, first appearing 1,000 to 4,000 years ago. Contemporary human-macaque commensalism at each monkey temple is shaped by the behavioral characteristics of the particular monkey popula- tion as well as the community’s unique geographic, social, religious, and economic factors. Human-macaque contact differs at the various monkey temples. At Sangeh, where tourism has become an important economic resource, macaques depend on visitor feeding for most of their nutri- tion and have learned to climb on visitors’ heads and shoul- ders to obtain food. Local photographers, who make a living photographing visitors with monkeys, encourage this behavior. Macaques, sometimes provoked by visitors, can become aggressive and will bite or scratch people. The Sangeh Temple Committee, which manages the Sangeh Monkey Forest, estimates ≈250 persons work in and around the monkey forest. Of the 82 persons who par- ticipated in the present study, 28% had been bitten by a macaque, and 6% had been bitten more than once. In com- parison, 700,000 tourists visit the 4 main monkey temples on the island of Bali (Padangtegal/Ubud, Sangeh, Alas Kedaton, and Uluwatu) annually and as many as 5% of these visitors are bitten by macaques (A. Fuentes, unpub. data). These data suggest that visitors receive the prepon- derance of macaque bites. Importance of SFV Infection in Humans The literature describes ≈40 cases of human infection with SFV. Long-term follow-up data are unavailable for many of these cases. However, no disease has been linked to SFV among infected humans. Furthermore, no cases of human-to-human transmission have been described, even among those receiving transfusions of blood products from a worker at a primate center who was later shown to be infected with SFV (38). Notwithstanding, more data are needed before SFV can be proclaimed a “virus without a disease.” First, SFV infection has not been extensively studied in immunocom- promised persons, so whether SFV has a more aggressive course in an immunologically “permissive” environment is unknown. Two persons died shortly after receiving baboon Figure 2. Phylogenetic analysis of simian foamy virus (SFV) DNA from several species of Indonesian primates and an infected human. BP 2, 5, and 6 represent Sangeh monkey temple macaques (Macaca fascicularis). P 18, 19, 27, 32, 37, 66, 67, and 70 are pet macaques (M. tonkeana) from Sulawesi, Indonesia. P48, 49 and 72 are pet macaques (M. maura) from Sulawesi, Indonesia. P75 is a pet M. fascicularis macaque from Sulawesi, Indonesia. All Sulawesi pet primate samples were collected during 2000. SFV-1mac represents a published sequence from a rhesus macaque (M. mulatta), and SFV-3agm is a published sequence from an African green monkey (Cercopithecus aethiops). SFVcpz is a published sequence from a chimpanzee (Pan troglodytes) and was used an outgroup for this tree. The SFV human strain (BH66) clustered with an SFV sequence amplified from BP6 one of the macaques at the Sangeh monkey temple. The SFV DNA tree was created with the neighbor-joining method by using the PHYLIP program (DNAdist; Neighbor). Bootstrap replicates were 1,000. Bootstrap values were calculated by using Seqboot, DNAdist, Neighbor, and Consense (PHYLIP programs). Bootstrap values 60% are shown. The SFV tree was plotted in Treeview. 1032 Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 11, No. 7, July 2005