Zoonoses: Contact with Monkeys Puts African Populations at Risk

  Animal diseases that infect humans pose a major threat to human health worldwide and often spread from non-human primates. A large-scale study, reported in PLOS Neglected Tropical Diseases, was conducted in southeastern Cameroon to assess how Cameroonian populations interact with nine species of monkeys. The behaviors observed—including frequent physical contact and the handling of bushmeat—expose adults to a very real risk of contracting new diseases.   Zoonotic diseases now account for more than 60% of emerging infectious diseases. And more than 70% of these zoonoses originate in wild animals. Due to the genetic similarities between humans and non-human primates, monkeys often serve as reservoirs or amplifiers for pathogens of numerous neglected tropical diseases, such as viral haemorrhagic diseases or arboviruses, parasites and bacteria, as well as retroviruses such as simian foamy virus, which pose a proven risk to human populations. A new study, led in particular by Tamara Giles-Vernick (Institut Pasteur) and Victor Narat (National Center for Scientific Research), explored human physical exposure to several primate species using field surveys, real-time data collection, qualitative interviews, and questionnaires on bushmeat handling practices. The study aimed to paint a comprehensive picture of the exposure of residents in southeastern Cameroon to nine species of monkeys, which are abundant around villages. Data were collected in 2016 and 2017 from hundreds of people. The researchers found that Cameroonian adults have frequent physical contact with primates, more so with monkeys than with great apes. These encounters most often occur during the hunting, butchering, preparation, and meat consumption of bushmeat, but also through injuries caused by gorillas. Approximately 85% of survey respondents reported having eaten monkey meat at some point in their lives. In general, the risk of exposure in a given village is positively correlated with the density of non-human primate populations and their proximity to human dwellings. The authors urge national and international authorities to work toward improving surveillance of humans in areas where monkey species are abundant and to raise public awareness about safer meat-handling practices. A multidisciplinary approach—resulting from research that combines the fields of ecology and the social sciences—must be adopted to ensure more effective surveillance of human and animal health, as well as risk communication to affected populations regarding neglected tropical diseases. In light of the World Health Organization’s (WHO) inclusion of “Disease X,” a suspected zoonotic agent with pandemic potential, to its latest priority action plan for research and development against diseases, new field tools capable of detecting the emergence of known or unknown zoonotic diseases are of paramount importance. The global community is, in fact, facing the emergence of new diseases, most of which must first be detected in animal populations.