Throughout Asia, humans and monkeys live side-by side in many urban areas. An international research team from the University of Washington, Fred Hutchinson Cancer Research Center and Jahangirnagar University has been examining transmission of a virus from monkeys to humans in Bangladesh, one of the world's most densely populated countries. The scientists have found that some people in these urban areas are concurrently infected with multiple strains of simian foamy virus (SFV), including strains from more than one source (recombinant) that researchers originally detected in the monkeys.
Simian foamy viruses, which are ubiquitous in nonhuman primates, are retroviruses like HIV. Retroviruses are shown to exhibit high levels of mutation and recombination - a potentially explosive combination.
Their paper, "Zoonotic simian foamy virus in Bangladesh reflects diverse patterns of transmission and co-infection" published in the Sept. 4 issue of Emerging Microbes and Infections (EMI), characterizes the simian retroviral strains that are being zoonotically transmitted and provides a glimpse into the behaviors of humans and monkeys contributing to the infections.
By analyzing what is happening at the human-primate interface, the researchers hope to protect humans from another deadly outbreak like HIV. Their focus is in Asia because it is a continent that has witnessed the emergence of several infectious diseases in the past decade. Asia also has a volatile combination of an increasingly mobile and immunocompromised population living in proximity with animals.
Since more humans have been shown to have been infected with SFV through primate contact than with any other simian-borne virus, the researchers reason that pinpointing the factors that influence SFV transmission and infection are important to a general understanding of how viruses can jump the species barrier.
"If we want to understand how, where and why these primate viruses are being transmitted, we need to be looking at SFV in Asia where millions of people and tens of thousands of macaques are interacting everyday and where we estimate that thousands of people could be infected with strains of SFV," said Lisa Jones-Engel, a primatologist with the National Primate Research Center at the University of Washington and the project leader. "These Asian rhesus macaques are Darwinian superstars. They are very responsive to change and, unlike many other species of primates, they are going to continue to thrive in human-altered habitats."
Jones-Engel said if researchers had been on the ground 50 years ago, they may have seen how simian immunodeficiency viruses (SIV) crossed the species barrier resulting in HIV.
"We have been playing catch up with the SIV-HIV question for years," she said. "We still don't know why only some viral strains are capable of establishing persistent infections in humans."
Jones-Engel said long-term surveillance is needed in the areas where humans and primates come into contact since it's unlikely that SIV/HIV will be the last primate virus to emerge into the human population.
In this study, researchers collected biological samples from hundreds of people and macaques from five urban sites as well as from a group of nomadic people who travel throughout Bangladesh with their performing monkeys.
According to the paper, the towns and villages that constituted research sites for the study are likely similar to hundreds or even thousands of sites throughout Asia, where humans live alongside macaques accustomed to their presence.