Days numbered for Silver Springs' monkeys? Study gives Florida reason for removal

By Christie Zizo, Digital Media Producer
Last Updated: Thursday, January 11, 2018, 8:21 PM EST

A new study by University of Florida researchers is giving state wildlife officials a reason to consider removing the roaming monkeys of Silver Springs State Park in Marion County.

  • Study looked at herpes B virus in Silver Spring State Park monkeys
  • Researchers think rhesus macaques could transmit herpes B to people
  • No documented cases of humans getting virus from monkeys in the wild
  • FWC wants to look at removing monkeys from Silver Springs State Park

The study, published Wednesday in the Centers for Disease Control and Prevention journal "Emerging Infectious Diseases," found that some rhesus macaques can shed the herpes B virus orally and transmit it to humans.

The virus is rare in humans. Fatal cases of the virus have only been reported in laboratory settings where humans interact with the monkeys.

Researchers took saliva and fecal samples from the monkeys at the park and found four to 14 percent of the monkeys transmitted the virus through saliva. 

At the end of the report's abstract, it says, "Management plans should be put in place to limit transmission of [herpes B virus] from these macaques."

The rhesus macaques are an invasive species native to Southeast Asia. They were first introduced to Silver Springs State Park in the mid-1930s, when they were intentionally released into the park to attract tourists.

The manager of the park’s glass-bottom boat operation released the monkeys to an island in the Silver River, not knowing the monkeys can swim. The monkeys have since been spotted in other areas outside the park, along the Ocklawaha River.

No one keeps a thorough record of encounters between the monkeys and humans at Silver Springs State Park, said Samantha Wiley, a University of Florida researcher who is a co-author of the study.

Wiley also said there has yet to be a documented case of herpes B in humans from a wild monkey encounter anywhere in the world. She said the issue is one her team wants to continue to study on a genomic basis.

Wiley said the researchers are interested in seeing the virulency of the pathogens. The study says stress activates the virus in the animals, and researchers only found evidence of viral "shedding" in samples collected during the fall breeding season — a stressful time of year for male monkeys.

The herpes B virus carried by the monkeys has been classified as “a low risk by high consequence pathogen,” a public health term. That’s enough for the Florida Fish and Wildlife Conservation Commission to be concerned, said FWC assistant executive director Dr. Thomas H. Eason, who issued this statement to Spectrum News Networks:

“Without management action, the presence and continued expansion of non-native Rhesus macaques in Florida can result in serious human health and safety risks including human injury and transmission of disease. 

“Additionally, macaques can negatively impact Florida native wildlife and pose potential risks to agriculture and recreation. Therefore, the FWC supports active management to remove these threats.”

No word on when FWC will begin discussing how deal with the monkeys. 

Encounters with rhesus macaques in Central Florida are often met with more amusement than concern. A highly-publicized video last year showed a family being chased by several monkeys at Silver Springs State Park. Humans feeding the monkeys is a common activity along the Silver River.

Monkeys have also been spotted in Apopka, Fruitland Park and even in Pasco County. A rhesus monkey on the loose in Pinellas County for more than two years was caught in October 2012. Blood tests showed the monkey carried herpes B. However, a woman who had been bitten by the monkey tested negative for the virus.

Information from the Associated Press was used in this report.