Asian Monkey Temple Visitors Warned of Virus Transmission

SEATTLE, Washington, July 25, 2005 (ENS) - An international team of scientists concerned about transmission of viruses from monkeys to humans are warning travellers to Asia not to pet or feed the numerous monkeys they may see at temples and other tourist sites. Feeding the animals, or even carrying food into a temple, can greatly increase the risk of a bite or scratch, which can lead to transmission of infection.

The warning comes from researchers in the United States, Canada and Indonesia who have identified the first reported case in Asia of primate to human transmission of a retrovirus found in macaques and other primates known as the simian foamy virus. So far this virus has not been shown to cause disease in humans.

The transmission of the virus from a monkey to a human took place at a monkey temple in Bali, Indonesia, the researchers report in the July issue of the journal "Emerging Infectious Diseases."

Monkey at one of Bali's numerous monkey temples. New research shows these primates may carry viruses transmissible to humans. (Photo credit unknown)

HIV, the virus that causes AIDS in humans, is believed to have originated as simian immunodeficiency virus, and jumped the species barrier to humans when African bushmeat hunters came into contact with blood from infected animals.

"The issue of primate-to-human viral transmission has been studied extensively in Africa, largely because that is where HIV originated," explains Dr. Lisa Jones-Engel, lead author of the study and a research scientist in the Division of International Programs at the University of Washington National Primate Research Center in Seattle.

"But there has not been much work on the topic in Asia, which has huge primate diversity and large human populations," she said.

For this study, the researchers tested blood samples from 82 people who work in or around a temple in Bali, as well as samples from macaques in the area. They found antibodies for simian foamy virus in the blood of one 47 year old farmer who visited the temple every day.

They confirmed the tests by performing a DNA analysis of the man's blood, and found that the SFV strain he carried was the same strain found in the temple's macaques. The man denied owning a monkey as a pet, or hunting monkeys for food.

He had been bitten once and scratched more than once by the temple's macaques.

A macaque at a monkey temple begs for food from a visitor. (Photo courtesy Lisa Jones-Engel)

On the island of Bali alone, there are more than 40 such temples, which are frequented by tourists from around the world. About 700,000 international tourists visit the island's four main monkey temples every year. Temple workers and people who live near the temples also have a great deal of contact with monkeys at the religious sites.

Researchers still do not know the long-term effects of simian foamy virus on humans. There are about 40 known cases of people being infected, through laboratory or zoo contact, or through bushmeat hunting in Africa. There are no known cases of human disease yet.

The majority of previous primate to human viral transmission research focused on bushmeat hunting, in which monkeys and other wild animals are hunted for food.

Though bushmeat hunting and consumption may be a significant factor in viral transmission in Africa, Jones-Engel says people in Asia come into contact with primates in many other ways - animal markets, primate pet ownership, urban performing primates, and zoos.

"In Asia, the amount of contact between humans and primates in temple settings dwarfs the contact due to bushmeat hunting," says Jones-Engel.

Also participating in the study were researchers at the University of Toronto; Udayana University in Denpasar, Bali, Indonesia; the University of Notre Dame; the Southern Research Institute in Frederick, Maryland; and the Southwest Foundation for Biomedical Research in San Antonio, Texas.

Tourist walking in Bali's Monkey Forest, near the Monkey Temple, is accosted by a resident primate. (Photo credit unknown)

"If you look at free-ranging monkeys in Singapore's nature reserves, you see that feeding by visitors is not allowed, and it is actively discouraged," says Gregory Engel, an attending physician at Swedish/Providence Hospital in Seattle, a clinical instructor of family medicine at the University of Washington, and a co-author on the study.

"Interspecies interaction there is very different, and rates of human-monkey contact are much lower," Engel said.

Limiting contact between primates and humans also can reduce the transmission of human infections to monkeys. Human measles can cause disease in monkeys and can even kill them.

Other primate species have already seen population losses because of infection by human illnesses. The "Gorilla Journal" reports that cases of illnesses in apes associated with human respiratory viruses and bacteria include influenza, pneumonia, herpes, measles, mumps, polio, and salmonella, as well as numerous parasites.