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Bushmeat trade, disease transmission risk
Confiscated bushmeat ‘poses virus threat’
Much of the trade in wildlife meat, or bushmeat, has its origin in Africa. Scientists have documented potentially dangerous viruses entering the US through illegally imported wildlife products. Testing of meats confiscated at American airports has revealed the presence of several pathogens that could pose a risk to human health. Retroviruses and herpesviruses were identified, some of them isolated from remains
of endangered monkey species.

The research study is reported in the journal PLoS One [see comment below]. Its authors say better surveillance measures are needed to
ensure this trade does not result in the emergence of new disease outbreaks in humans. “Although the findings to date are from a small
pilot study, they remind us of the potential public health risk posed by illegal importation of wildlife products — a risk we hope to
better characterize through expanded surveillance at ports of entry around the country,” said Dr Kristine Smith, from EcoHealth Alliance,
who led the investigation team.

Scientists estimate that some 75 percent of emerging infectious diseases affecting people have come from contact with wildlife. Some
of this is the result of animals biting humans, but the handling and consumption of infected meats is also considered a significant route
of transmission. Classic examples of infections that have jumped across the species include HIV/AIDS [Human immunodeficiency
virus/Acquired immunodeficiency syndrome], which is thought to have originated in primates, and SARS [Severe acute respiratory syndrome],
an infection that caused global concern in 2003. Follow-up work traced its beginnings to Chinese restaurant workers butchering the cat-like
Asian palm civet [which in their turn had acquired the virus from bats – Mod.CP].

The PLoS One study is a 1st attempt to screen for potentially hazardous pathogens in confiscated meat products entering the US. The
scientists examined animal remains passing through 5 international airports, including John F Kennedy in New York — one of the busiest
hubs in the world. The smuggled meats — some found in postal packages, some discovered inside suitcases — were tested 1st to make
a species identification. This showed up several non-human primates, included baboon and chimpanzee, but also rodents.

The raw, smoked and dried meats were then tested for a number of viruses known to be capable of infecting humans. Among the pathogens
identified were a zoonotic retrovirus, simian foamy viruses [actually simian foamy viruses that nay be possible zoonotic retroviruses — see
comment below], and several nonhuman primate herpesviruses.
No one really knows the scale of the illegal trade in wildlife meat, or bushmeat as it is often called, but a 2010 study estimated that 5
tonnes of the material per week was being smuggled in personal baggage through Roissy-Charles de Gaulle airport in Paris, France. And in
addition to the meat products, there is a big trade in live wild animals. Much of this is perfectly legal and supplies the pet
industry. Nonetheless, these animals also require improved pathogen surveillance, say the researchers.

“Exotic wildlife pets and bushmeat are Trojan horses that threaten humankind at sites where they are collected in the developing world as
well as the US. Our study underscores the importance of surveillance at ports, but we must also encourage efforts to reduce demand for
products that drive the wildlife trade,” said Ian Lipkin of Columbia University’s Mailman School of Public Health. One key aspect of
concern highlighted by the team was the identification in the samples of some endangered species, including the Guinea baboon and the sooty
mangabey, an Old World monkey.

Marcus Rowcliffe, from the Institute of Zoology in London, UK, and who was not connected with the research, commented: “The extent to which
an intercontinental luxury meat market may be developing is of major concern, because if that is happening it could have very worrying
impacts on wild populations. “This whole area is marked by a lot of unknowns which is why we need more studies like this.”

Communicated by:

[This report is based on the PLoS One paper: “Zoonotic Viruses
Associated with Illegally Imported Wildlife Products. By: Smith KM,
Anthony SJ, Switzer WM, Epstein JH, Seimon T, et al. (2012) PLoS ONE
7(1): e29505. doi:10.1371/journal.pone.0029505

The abstract of the paper reads: “The global trade in wildlife has historically contributed to the emergence and spread of infectious
diseases. The United States is the world’s largest importer of wildlife and wildlife products, yet minimal pathogen surveillance has
precluded assessment of the health risks posed by this practice. This report details the findings of a pilot project to establish
surveillance methodology for zoonotic agents in confiscated wildlife products. Initial findings from samples collected at several
international airports identified parts originating from nonhuman primate (NHP) and rodent species, including baboon, chimpanzee,
mangabey, guenon, green monkey, cane rat and rat. Pathogen screening identified retroviruses (simian foamy virus) and/or herpesviruses
(cytomegalovirus and lymphocryptovirus) in the NHP samples. These results are the 1st demonstration that illegal bushmeat importation
into the United States could act as a conduit for pathogen spread, and suggest that implementation of disease surveillance of the wildlife
trade will help facilitate prevention of disease emergence.”

The pathogen screening was based on sequence analysis and virus isolation was not attempted in this analysis. Only simian foamy
viruses (SFV) and herpesviruses were detected in the nonhuman primate (NHP) bushmeat samples. All NHP samples were negative for SIV [simian immunodeficiency virus) and STLV (simian T-cell leukaemia virus) sequences. All rodent samples were negative for leptospira, anthrax,
herpesviruses, filoviruses, paramyxoviruses, coronaviruses, flaviviruses, and orthopoxviruses. Two genera of herpesvirus were
detected in NHP specimens, cytomegaloviruses (CMV; a betaherpesvirus) and lymphocryptoviruses (LCV; a gammaherpesvirus). Multiple viruses were detected within some samples.

These results are consistent with the origin of the shipments from West Africa and included meat derived from species of conservation
importance. The results of this study are comparable with those reported in a separate survey at Charles de Gaulle Airport, Paris.

SFV is considered to be a known zoonotic infection of humans exposed to NHPs. However, the mode of transmission to humans is poorly
understood and while most infected people reported sustaining a NHP exposure (mostly bites) others did not, suggesting a less invasive
mode of infection is possible. These viruses are probably not easily spread from human-to-human, although persistent infection has been

The finding of SFV DNA in the bushmeat samples highlights a potential public health risk of exposure to these tissues. Unlike most
retroviruses whose RNA genome is packaged in the viral particles, foamy viruses are unusual in that DNA and/or RNA can be present in the
infectious virus particles. Thus, finding of only DNA (and not RNA) in these analyses does not exclude that the possibility that the SFV in
these tissues many be infectious. Nonetheless human infection with SFV is of concern because increases in the pathogenicity of simian
retroviruses following cross-species transmission have been well documented (e.g., HIV-1 and HIV-2).

Like retroviruses, herpesviruses can cause long-term latent infections in their host. Most herpesviruses are host-specific, yet particular
strains are capable of causing severe disease in the non-host, examples of which include agents of malignant catarrhal fever,herpes B
virus and CMV. Human CMV is typically asymptomatic in humans, with the exception of immunocompromised persons. Similarly, many NHPs are asymptomatic hosts of CMV that do not typically infect other species, including humans.

Overall these data are indicative of moderate risk of transmission of exotic pathogens by intercontinental trade in bush meat, but as yet do
not identify a specific imminent threat. – Mod.CP]

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