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No evidence of coronaviruses or other potentially zoonotic viruses in Sunda pangolins (Manis javanica) entering the wildlife trade via Malaysia

Our take —

In this study, available as a preprint and thus not yet peer reviewed, testing of 334 pangolins entering the wildlife trade in Malaysia showed animals were negative for five viral families, including coronaviruses. These results suggest that coronaviruses are not circulating naturally in pangolins and that exposure to viruses likely occurs “downstream” in the wildlife trade through close contact with humans and other animals.

Study design

Ecological

Study population and setting

Throat and rectal swabs were collected from 334 live Sunda pangolins (Manis javanica) confiscated or rescued from the wild in Peninsular Malaysia (n = 286 confiscated, n = 3 wild-rescued) and Sabah state (n = 40 confiscated, n = 5 wild-rescued) between August 2009 and March 2019. Samples were tested by PCR for the presence of genetic material of five viral families (Coronaviridae, Filoviridae, Flaviviridae, Orthomyxoviridae, and Paramyxoviridae).

Summary of Main Findings

None of the collected swab samples tested positive for genetic material for any of the viral families. Genetic analysis of pangolins suggests that the confiscated pangolins originated from Malaysia, Brunei, or Indonesia.

Study Strengths

The study had a moderately large population size collected over ten years, which is substantial given the critically endangered status of Sunda pangolins. Targeting animals entering the “upstream” section of the wildlife trade provides important context for understanding where pangolins are exposed to viruses.

Limitations

The researchers only assessed the presence of viral genetic material via PCR, which would indicate active infection. Additional serological analysis could have provided information on animals’ past exposure to these viruses. Sampling was sporadic across regions and years, so these results cannot confirm the absence of viruses among pangolins.

Value added

These results indicate that pangolins entering the market chain are not carrying viruses, suggesting that exposure of pangolins to viruses (including reports of coronaviruses similar to SARS-CoV-2) may have occurred later in the wildlife trade network from infected humans or other animals within markets or during transportation to their final destination.

This review was posted on: 10 August 2020