Not just bad for wildlife (Image: Cyril Ruoso/Minden Pictures/FLPA)

The illegal bushmeat trade not only threatens the survival of endangered species in Africa, but could also lead to outbreaks of deadly human diseases in North America and Europe.

A pilot study of bushmeat seized at US airports has found ape and monkey parts infected with retroviruses and herpesviruses. None of these viruses were known killers, but this small study has just scratched the surface of a trade that is known to be large.

“Seventy-five per cent of emerging diseases move to humans from wildlife, either directly or through our livestock,” says Kristine Smith, a wildlife veterinarian with the EcoHealth Alliance in New York City who led the study. The bushmeat trade could provide a hidden conduit for disease transmission, the researchers say.


The legal trade in exotic pets is already known to pose a similar risk. In 2003, an outbreak of monkeypox infected dozens of people across several US states. It was traced to an animal dealer near Chicago, where an imported Gambian giant rat gave the virus to prairie dogs that were later sold as family pets.

A thriving trade in smuggled bushmeat in Europe and North America has been uncovered in recent years. Smith’s study, which involved a large team from organisations including the Wildlife Conservation Society and the American Museum of Natural History, both in New York City, is the first to examine how the smuggling could trigger outbreaks of human disease.

Meat raid

The researchers screened samples of meat seized at five major US airports for the bacteria that cause anthrax and leptospirosis, plus a wide range of viruses. In all, they examined meat from an estimated 60 individual animals, 25 of them primates – including baboons, chimpanzees, mangabeys, guenons and green monkeys.

All the rodent meat studied seemed to be free of pathogens, but about half of the primate samples were infected with at least one virus. Eight of the samples contained simian foamy virus, which can be transmitted to people who have contact with monkeys or apes. While foamy virus hasn’t itself been shown to cause human disease, it is related to potentially deadly retroviruses such as simian immunodeficiency virus (SIV), thought to be the origin of HIV.

“Foamy virus may be a marker for these more serious infections,” says William Switzer of the US Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia, who was involved in the study.

On the alert

The new study shows that we need better systems for monitoring both illegal and legal trades, says Gerald Keusch of Boston University, lead editor of a 2009 US Institute of Medicine report on surveillance for diseases spread from animals. “When a threat like H5N1 [bird] flu or SARS comes up, we establish surveillance,” he says. “As soon as it appears that the threat is no longer at the red level, the support for those systems tends to dissipate.”

The CDC says that it is now expanding the study to include 18 of its 20 quarantine stations at major ports of entry into the US.

Beefing up surveillance will require coordination with other agencies. The CDC shares responsibility for screening imported animals and animal products with the US Department of Agriculture, the Fish and Wildlife Service and the Department of Homeland Security. In November 2010, a report from the Government Accountability Office warned of “gaps that could allow the introduction of diseases into the United States”.

Journal reference: PLoS One, DOI: 10.1371/journal.pone.0029505