Simian Foamy Virus Infections in Handlers of Nonhuman Primates

Disease Update

Synopsis: While not representing immediate cause for alarm, spumaviruses have been transmitted to humans in occupational settings; handlers need to be well-oriented and educated about the rules of prevention and response.

Source: Neumann-Haefelin D, Schweizer M. Nonhuman primate spumavirus infections among persons with occupational exposure—United States, 1996. MMWR Morb Mortal Wkly Rep 1997;46:129-131.

Several simian retroviruses are capable of infecting humans. A laboratory worker was infected with simian immunodeficiency virus during a laboratory experiment in 1993, and this was reported in 1994. The Centers for Disease Control and Prevention (CDC) instituted a survey for simian foamy virus, a naturally occurring simian retrovirus infection, in 1995, using first a linked surveillance program and then a voluntary testing and counseling program. A survey of 231 sera from animal handlers turned up three bona fide infections proven by PCR analysis (1.3%). Two of the workers have regular, unprotected sex in monogamous relationships, and neither partner is infected. No data concerning sexual partners are available from the third. None of the workers has manifested a disease identified with this infection and, apart from age-related illness in one, the workers are entirely healthy. The CDC is extending its screening program to include other simian retroviruses and more workers.

So, for now, spumaviruses do not represent immediate cause for alarm. These are poorly characterized viruses about which little is known. The advent of good PCR assays has made this analysis possible and will certainly expand the ability to accurately identify infected individuals. Nevertheless, a lot more needs to be done to prevent critical exposures to handlers of non-human primates. All of the infected individuals have a strong history of multiple critical exposures, whether bites or sharps or scratches. Indeed, such data will become even more important as xenotransplantation techniques become more widely used. Probably the most feared of simian infections for handlers is herpes B virus infection, which remains rare but can be potentially fatal. Confusion about handling potential exposures to herpes B is very common. Most feared exposures turn out to be false alarms where proper procedures are followed; exposed workers counseled appropriately; serum from animal and worker tested by accurate virological and/or serological assays. Every institution using such animals, however, should have a carefully outlined mechanism for how to respond to exposures quickly and effectively. Handlers, including students, need to be well-oriented and educated about the rules of prevention and response. For now, though, spumavirus infections are not on the urgent list.