The Next Big Virus: Monkey Business?

When you think of primate research, do you image a middle-aged man wandering through a remote African village? Perhaps you conjure a group of young post-docs pushing through a lush, thick jungle? Enter Lisa Jones-Engel, a senior research scientist from the Washington National Primate Research Center in Seattle. This youthful female researcher tracks monkey viruses down the crowded streets and markets of Bangladesh and into the Buddhist temples of Bali.

While many primate-related viruses (Marburg, Ebola, HIV) originated in Africa in recent decades, you may wonder why this researcher is focused on Asia. "So much of the focus on viral transmission from primates to humans has been in Africa," says Jones-Engel.  "But in Africa, interaction between humans and other primates is on the decrease, mainly because bushmeat hunting and infectious diseases have taken a toll on primate populations."

Part of what makes Asia the next potential hot zone for primate-related viruses is its burgeoning human population—currently estimated at 4 billion while Africa has less than 1 billion. Many of these people live in densely populated areas and come into contact with animals in a variety of contexts. Over the past decade, Asia has been the origin of deadly diseases from animals, such as avian flu and SARS.

Asia's rapidly growing population not only increases the number of people who might become infected with a disease that jumps from animals to humans, it also brings more animals, especially primates, into contact with humans. That's because expanding villages, towns and cities have encroached on primate habitats, and certain smaller monkeys, such as rhesus and long-tailed macaques, thrive and multiply in these human-altered areas.

Asia's human population explosion coupled with its large populations of urban macaques makes many parts of South and Southeast Asia the new hot-bed of human-monkey contact, says Jones-Engel.

Take densely populated northern India, for instance. It's now estimated that more than a quarter million macaques that formerly inhabited forested areas now live in urban habitats.

Asian cultures bring monkeys and humans together

When we're looking at potential disease transmission, we need to look at the places where there's the most contact between humans and other primates, says Jones-Engel. Asia is the best place to look, not just because of the overlap between dense human populations and dense primate populations. It's also because of the many roles monkeys play in a range of Asian societies.

While bushmeat hunting is the primary source of primate-human interaction in Africa, monkeys are far more prevalent in everyday life in many parts of South and Southeast Asia.

In Asia, monkeys aren't just seen as food. Some people keep monkeys as pets, while others train monkeys to be performance animals. These Asian traditions greatly increase the chances of human-monkey contact.

But it doesn't stop there. Because the small macaques are as much a part of the urban landscape as squirrels are in the United States, monkeys are often encountered roaming through the streets, parks, and open markets, where they may beg for food—or sometimes even try to pilfer a grocery bag from an unsuspecting human.

Perhaps because of their human-like qualities, their presence isn’t limited to the outdoors. "The monkeys in Asia are very cosmopolitan," says Jones-Engel. "You will sometimes see monkeys strolling through the mall—or even riding the bus."

From the Buddhists in Thailand to the Hindus in India and Bali, monkeys are a revered animal in religious traditions throughout many parts of Asia, bringing humans and monkeys into regular contact.

"In Bali, the people leave beautiful offerings with rice, crackers and flowers in front of their houses and on temple shrines," says Jones-Engels. "The monkeys are thinking: this is the greatest deal on earth, I've got takeout five times a day."