They have a herpes virus that can be fatal to humans. They are randy. And their population could double by 2022.
“They” are a group of about 200 feral monkeys — rhesus macaques, to be exact — in Silver Springs State Park in central Florida’s Marion County. There is also a colony of these monkeys in Puerto Rico.
According to a 2018 report by the Centers for Disease Control and Prevention, researchers found that these rhesus macaques can shed the herpes B virus, known as macacine herpes virus 1 or McHV-1, and this puts “humans at risk for exposure to this potentially fatal pathogen.”
No humans recently, so far, have contracted the monkey B virus. The virus is transmitted by bites and scratches and simian bodily fluids — monkeys are known to, sorry, fling their poop, so that could be one way to spread the infection, too.
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For these reasons, the CDC issued a warning that officials should work on plans to limit the transmission of McHV-1 from these macaques.
“It’s going to be a problem. Continual growth of that population is going to occur without intervention,” University of Florida professor Steve Johnson told ABC affiliate WFTV9 on Thursday.
Johnson was part of a team of UF researchers that published the study of the monkeys over a nearly 15-year period starting in 2000 and reported by the CDC last year.
The researchers analyzed blood and saliva from 317 of the monkeys and found that 25 percent of the population carried the virus and between 4 to 14 percent of the infected “were actively shedding the virus during the stressful fall mating season of 2015.”
The infection doesn’t produce clinical illness in macaques, but about 50 percent of the infections could cause fatal encephalitis in humans if left untreated, the UF study found.
So far, researchers have documented 50 cases of the monkey B virus spreading to humans, with 21 of these proving fatal since the virus was identified in 1932.
For humans, untreated monkey B virus can feel like the flu, the CDC said, but could progress neurologically and have symptoms such as double vision and, later, paralysis and potential death.
The risk of transmission is low, the CDC added, but noted “Immunologic surveillance, reporting and diagnostic investigations in humans are lacking.”
By 2022, Johnson told WFTV that the rhesus macaques’ population could swell to 400 and that Florida would have to take some measures to contain the species — which is considered invasive.
“Remove the animals from the environment … [or] remove the animals, sterilize the females and put them back,” Johnson told WFTV, noting that the solution isn’t without risk for trappers.
The Silver Springs State Park monkeys got there in the 1930s when “the captain of a glass-bottom boat released a handful of macaques on an island [off the park] to amuse tourists,” ARS Technica reported. That part of the park was closed long ago.
The simians are good swimmers, so they were able to establish themselves on the park grounds and the nearby Ocala National Forest.
The Journal of Wildlife Management reported on the UF study in October and noted that management efforts to reduce the population hasn’t been easy because park visitors like seeing the monkeys.
“They’re really charismatic and the public really likes them, so they’re really hard to manage,” C. Jane Anderson, lead author on the study, told The Wildlife Society.