Florida Monkeys Carry Deadly Herpes Virus That’s Fatal To Humans, Officials Sound Chilling Warning

Florida officials detected a strain of herpes B virus in macaques that is often fatal in humans, especially without treatment.

A monkey is shown among people, presumably tourists and the primate shows no fear as it sits atop a stone ledge
Evgeny Svalov / Shutterstock

Florida officials detected a strain of herpes B virus in macaques that is often fatal in humans, especially without treatment.

Officials in Florida have issued a dire warning: Don’t feed, take selfies, or touch a monkey roaming wild in the Sunshine State, especially macaques in Silver Springs State Park — doing so could kill you due to a potentially fatal herpes B virus (or McHV-1) carried by the primates.

Monkeys in the Northern Florida park could be hazardous to your health, according to a report out on Thursday by the Verge. Officials are warning visitors and residents to stay away from invasive rhesus macaques that are now known to carry the herpes B virus.

Samantha Wisely works as a wildlife biologist at the University of Florida. She is also an author of a study that found the existence of a herpes strain in wild monkeys that can lead to a terminal prognosis in humans. Remarkably, the herpes virus in question does not harm the host, in this case, the rhesus macaque.

As the Verge wrote, about a quarter of the monkey population in Florida carries the virus, which has a similar manifestation to what is seen in human infections (cold sores). Additionally, very few suffered active infections.

Apparently, the source monkeys “released the virus in their spit during their fall breeding season, researchers report in the journal Emerging Infectious Diseases. And the wild monkeys’ poop turned out to be pristine — at least, as far as herpes B was concerned.”

Wisely says that she and her colleagues compiled data alarming enough to require warnings to healthcare and government officials. Still, the body of knowledge on the herpes B virus in wild species of monkeys is lacking, and scientists struggle to explain many facets of the disease. Wisely calls McHV-1 “low-risk” in terms of coming down with a deadly condition, but the consequences of contracting the virus once you do have it are high; you can die from it.

According to an article titled “Predation of artificial nests by introduced rhesus macaques,” found on the UFL website, Florida is host to several invasive monkey species and has the largest concentration of any state. Of the three known primates introduced to Florida — vervet monkey, squirrel monkey, and the rhesus macaque — the latter is the most destructive and is the one that harbors the herpes B virus.

In 1930, the macaque monkey arrived in Florida as part of an experiment to prop up tourism. Over two decades, the original dozen or so monkeys introduced to the state multiplied in great numbers. Their infiltration led to a public outcry, which then led to legalized trapping to control the rampant population.

Based on the most recent tally in 2015, less than 200 macaques remain in Silver Springs State Park. Still, it only takes one sick monkey to pose a health hazard to unsuspecting humans.

The herpes B virus is somewhat elusive. The pathogen targets the monkey’s central nervous system and hides. There, it remains inactive until the host’s immune system is weakened or it is overwhelmed by stress. Researchers say they detected the virus through body fluid secretions in a population of monkeys.

“To be honest with you, we found feces on children’s slides, and in the playground,” Wisely said.

Researchers said no monkey-to-human transmissions of the virus or fatalities have been observed at this time in “free-ranging” monkeys. There are three possible explanations, despite the frequent interaction between humans and macaques, globally; most infections and deaths from the McHV-1 virus have been limited to controlled environments (e.g. laboratories).

First, there could be a larger number of strains — some that have mutated — that have not been accounted for, and the lab strains may be more infectious/deadly than types found in natural settings. Second, monkeys allowed to roam freely may transmit the McHV-1 virus with less frequency compared to lab macaques. Third, the pathogens and infections in humans — contracted from free-ranging monkeys — may be subject to misdiagnosis and reporting, according to the CDC discussion portion of the abstract.

Wisely points out that it is particularly important to determine ways to control and treat the virus before it mutates or is spread to humans outside of controlled settings. Because the virus attacks the brain, fatalities occur in 70 percent of cases.

At this time, officials said there is no need to panic, but the public should exercise caution when encountering any monkey species in the wild. Wisely adds that people should not feed, take selfies, or get the urge to snuggle with free-ranging animals; it could be dangerous.

“It doesn’t do the wildlife any good and it doesn’t do you any good,” Wisely cautions.