Primatologist Lisa Jones-Engel during her study on the virus in Sulawesi, Indonesia. (Above) A temple monkey. Picture courtesy Jordan Stallard

New Delhi, July 17: Monkeys may be revered residents in temples across South Asia. But scientists have warned that a virus called SFV might jump from temple monkeys into humans.

Scientists say SFV ? or simian foamy virus ? does not cause disease in monkeys or humans, but they point out that the human immunodeficiency virus (HIV) that causes AIDS emerged decades ago after a relatively harmless virus crossed the “species barrier” from monkeys into humans.

A study released last Thursday has reported Asia’s first case of SFV moving from monkeys to a human ? a farmer who was a frequent visitor to a 17th-century Hindu temple in Bali, Indonesia.

The virus, present in the saliva of infected monkeys, can slip into humans through scratches or bites.

People who live, work or visit temples and have close encounters with resident monkeys may be at risk of getting infected with SFV, American and Indonesian scientists said in their study published in the journal Emerging Infectious Diseases.

“There is a possibility that SFV could infect a human and then mutate into a disease-causing virus,” Dr Lisa Jones-Engel, a primatologist at the University of Washington in Seattle and lead author of the study, told The Telegraph in a telephone interview.

“But our experience with SFV is limited. There has been little opportunity to study its effect over time,” she added.

Over the past decade, only 40 people, all outside Asia, have been infected with SFV.

All infections were among people who had either hunted or consumed monkeys or among workers who had come into contact with infected monkeys. The virus has not caused illness in monkeys or people and there is no evidence of human-to-human transmission, Jones-Engel said.

The US-Indonesian team examined 82 regular visitors to a temple in Bali that sheltered about 200 macaques and found a 47-year old farmer infected with SFV. He had been bitten once and scratched several times by monkeys.

Virologists say the finding is not surprising. Animal viruses slip into humans whenever they get a chance.

“The human genome has viral genome residues that have accumulated over time,” says Uday Ranga, a virologist at the Jawaharlal Nehru Centre for Advanced Scientific Research in Bangalore.

“Such viruses remain harmless most of the time, but occasionally they mutate to cause disease,” said Dr Shahid Jameel, the head of virology at the International Centre for Genetic Engineering and Biotechnology in New Delhi. “It’s too early to predict the long-term outcome of SFV infections in humans.”

The new study has said that temples in South Asia may account for more human-primate contact than any other context. The Vrindavan temple near Mathura, the Durga temple in Varanasi, the Kamakhya temple in Guwahati and the Jhakhu temple in Himachal Pradesh are among temples teeming with monkeys.

In Nepal, monkeys are found in Kathmandu’s Pashupatinath temple. Bali has about 45 monkey temples.

“Visitors need to be told not to feed monkeys and not to carry food,” Jones-Engel said. Though there is no evidence from India that centuries of human-monkey contact in temples has led to any disease, there is need for surveillance and caution, she added.

“We need studies such as this in India, but we don’t have enough virologists or resources,” said Dr Ravi Vasanthapuram, the head of virology at the National Institute of Mental Health and Neurosciences in Bangalore. “And we have more pressing problems such as encephalitis or HIV.”

Most studies on virus transmission have focused on hunting and the consumption of monkey meat in Africa.

Scientists believe that HIV emerged from a monkey virus that jumped from monkeys into humans when hunters came into contact with blood of infected animals.

Jones-Engel and her husband, Gregory Engel, professor of public health, have spent nearly five years exploring human-monkey interaction in Nepal and Indonesia. She said she has never had an opportunity to study monkey-human contacts in India where monkeys are revered as symbols of Hanuman, the mythical monkey god, and fed peanuts and bananas by visitors to temples.