Morgan Island, also known as “Monkey Island,” is an uninhabited island off the coast of South Carolina, nestled within Beaufort County. It is home to a substantial colony of free-ranging rhesus macaques, relocated from Puerto Rico in 1979-1980. The island serves as a controlled breeding environment for these monkeys, providing a significant asset for biomedical research. The health status of this primate colony is of considerable public interest.
The Specific Health Concern
Rhesus macaques on Morgan Island carry Macacine herpesvirus 1, known as Herpes B virus. This virus is a naturally occurring alphaherpesvirus, closely related to human herpes simplex viruses. In macaques, Herpes B typically causes mild or asymptomatic infections, similar to human cold sores. Infected monkeys may exhibit mild oral or genital lesions, which usually heal spontaneously within one to two weeks.
Infected monkeys carry the virus for life, remaining latent in their nervous system. The virus can reactivate, especially during stress, leading to shedding in bodily fluids like saliva, urine, and feces. Up to 80% of adult macaques in closed colonies are seropositive for Herpes B virus, indicating past exposure and presence of antibodies. This widespread prevalence highlights that it is common for these monkeys to carry the virus.
Transmission and Human Risk
While generally benign in macaques, Herpes B virus can be extremely dangerous and often fatal to humans. Human infections are rare, but can lead to severe neurological dysfunction, including encephalitis, with an approximately 80% fatality rate if left untreated. Symptoms typically appear within three days to one month following exposure, and can include flu-like symptoms, fever, muscle aches, headache, and vesicular skin lesions at the exposure site. As the disease progresses, it can lead to ascending paralysis, neurological impairment, and respiratory failure.
Transmission to humans primarily occurs through direct contact with infected monkey bodily fluids. This includes bites, scratches, or contact with contaminated saliva, urine, or feces. Exposure can also happen indirectly through contaminated tissues, cell cultures, or needle-stick injuries in laboratory settings. Although person-to-person transmission is extremely rare, one documented case has occurred. The risk to the general public from the Morgan Island colony is considered very low due to the island’s isolation and strict access protocols.
Island Management and Research Significance
Morgan Island serves as a primate research facility, providing a controlled environment for rhesus macaques. Monkeys were moved to the island in 1979 after a Herpes B outbreak in Puerto Rico, demonstrating the importance of isolation. The island functions as a breeding and quarantine facility, supplying monkeys for various biomedical studies, including research on vaccines and treatments for diseases like Ebola and HIV. Annually, between 400 and 600 monkeys are transferred from the island to specialized laboratories for research; no testing occurs directly on Morgan Island.
Strict biosecurity measures and protocols prevent human exposure to the virus and ensure personnel safety. These measures include specialized training, mandatory use of personal protective equipment, and veterinary care for the animals. The island’s isolation, with public access strictly prohibited, is a key component of its management strategy, minimizing the risk of disease transmission to the broader population. The colony, owned by the National Institute of Allergy and Infectious Diseases (NIAID) and managed in partnership with the South Carolina Department of Natural Resources, balances its scientific value with necessary precautions associated with the Herpes B virus.