A man was recording earlier this week when a monkey ran straight at him in Silver Spring State Park.
The monkeys, which are native to south and southeast Asia, have become the big attraction at the park.
At least 300 rhesus macaques live in Silver Spring State Park and some of them carry a rare and deadly form of herpes could put humans at risk as the population grows.
Experts say the species is rapidly breeding and could double in population within five years.
About 30 percent of the species carries the rare and deadly herpes B virus. While it is rare for it to spread from monkeys to humans when it does happen, humans can be put at risk, the report says.
Herpes B can cause inflammation of the brain and spinal cord and also could lead to brain damage or death.
