Wild Macaques Pose Hidden Herpes Threat in Florida

Invasive rhesus macaques in Florida are now understood to carry the herpes B virus, a pathogen that can be fatal to humans. First introduced to Silver Springs State Park in the 1930s, these macaques have established thriving populations. Research indicates that approximately 25% of the sampled macaque population between 2000 and 2012 showed antibodies to the virus, with infection rates increasing with age.

The herpes B virus, while harmless to macaques, can lead to severe, potentially fatal encephalitis in humans. Transmission typically occurs through bites or contact with infected bodily fluids. Studies utilizing saliva samples revealed active viral shedding in a small percentage of animals, particularly during the fall breeding season. Genetic analysis confirmed the virus is nearly identical to strains known to cause severe human illness.

Despite the documented risks, no human cases of herpes B virus contraction from free-ranging macaques have been confirmed as of the study's publication, with all documented human infections linked to captive animals. However, the close interactions between humans and macaques in areas like Silver Springs State Park, where boaters feed the animals at close range, increase the likelihood of encounters and potential transmission, creating a significant occupational health concern.