The subfamily Alphaherpesvirinae includes herpes simplex virus types 1 and 2 (HSV-1 and HSV-2, respectively) and herpes virus B (HVB)1. In their primary hosts, they cause low-virulence infections, but can confer devastating effects when other animal species are infected1,2. A 24-year-old woman was bitten by a healthy young brown howler monkey (Alouatta guariba). She presented with a vesicle where she had been bitten, along with local pain. It regressed spontaneously but recurred many times (Figure 1). She tested immunoglobulin (Ig)G-positive and IgM-negative for HSV-1 and HSV-2. Vesicle fluids were aspirated for virus culture and polymerase chain reaction assays, which identified HSV-2. The patient was successfully treated (Figure 2).
Humans are natural hosts to HSV-1 and HSV-2 Meanwhile, nonhuman primates can present with severe repercussions1,2. Old World primates are natural HVB reservoirs2,3. HVB is often lethal in humans and can be transmitted after a bite from an infected monkey3. On the inoculation site, skin lesions similar to those of herpes simplex may occur2,3. Myeloencephalitis with an 80% lethality rate is reported1–3. The possibility of it being a case of HBV transmitted by a New World primate was considered. The case described herein is rare: transmission of a human virus by a wild animal that was surprisingly asymptomatic. The monkey was possibly infected with HSV-2 after contact with its previous human owner. Animals harboring human viruses can lead to serious outcomes, as humans exposed to animal viruses can exhibit unpredictable results, emphasizing the importance of biosafety practices in handling wild animals.