A new study warns that performing monkeys in Indonesia carry several viruses that could infect humans during the close contact common to street shows.

Scientists have long known that monkeys and other primates can be sources of new viruses that morph into types that can kill people.

HIV, the virus that causes AIDS, is thought to have originated with primates in Africa and jumped species during contact with natives who ate their meat.

Recently, the fear of viral evolution has led world officials to warn against a potential flu pandemic should a deadly bird virus evolve the ability to jump from person to person.

Close contact

Performing monkeys in Jakarta, Indonesia's capital, carry several so-called retroviruses that are capable of infecting people but which might not show effects for years, it was announced today by researchers.

Retroviruses reproduce by implanting their genetic material into a host cell's DNA.

The monkeys were seen climbing on people and engaging in other close contact that could lead to a bite or scratch and then an infection of monkey fluid, the scientists said.

"The risk of viral transmission in this context is unclear," Michael Schillaci, professor of social sciences at the University of Toronto at Scarborough and lead author of a report in the December issue of the journal Tropical Medicine and International Health. "But the contact here can be very intense."

Markets where performing monkeys are sold pose another threat, the study found. Different species of wild monkey and other animals are brought together in often unsanitary conditions.

"The market is a condensed area for mixing species and pathogens," said Gregory Engel, a physician at Swedish/Providence Hospital in Seattle. "The animals may be sick or in bad shape there, and they're mixed with other animals that potentially could have pathogens, and then they're put into contact with a dense human population."

What monkeys carry

The scientists took blood samples from 20 performing macaques in Jakarta. Here's what they found in one or more of the creatures:

— Simian (ape or monkey) foamy virus (SFV); has not been shown to cause disease in humans but has been detected in other monkey-human interaction settings in Asia

— Simian retrovirus (SRV); shown to infect humans in a laboratory setting but yet to be associated with any disease in humans

— Simian T-cell lymphotropic virus (STLV); believed to be the primate ancestor of the human version of the virus, HTLV, a known cause of T-cell leukemia in people

— Herpes B virus, also known as CHV-1; rarely infects humans but, in the 40 known human cases, associated with an 80 percent fatality rate

The small study suggests further testing should be done on more monkeys in more locations, the researchers said. Performing monkeys are used in India, Pakistan, Thailand, Vietnam, China, Japan and Korea.

The scientists encourage people who live in or visit the region to avoid close contact with performing monkeys.

"People aren't looking at Asia, and they need to do so, because viruses are emerging on that continent," said study leader Lisa Jones-Engel of the University of Washington. "There is a large, diverse population of primates there, and a huge human population in dense urban centers, so there's the potential for viral transmission across the species barrier."

In July, Jones-Engel and colleagues announced the first known case in Asia of simian foamy virus (SFV) being transmitted from monkeys to humans.

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