Surveillance for PRRS Virus, PCV2 and Influenza A Viruses among Smallholder Swine Farms in Viet Nam

Virological and serological analyses confirm endemic co-circulation of porcine reproductive and respiratory syndrome virus (PRRSV), porcine circovirus type 2 (PCV2) and influenza A virus (IAV) within one province in south Viet Nam. The researchers there also found oral-fluids collection shows promise for future field research on respiratory porcine viruses.
calendar icon 7 October 2014
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Researchers based in Viet Nam have evaluated the feasibility and utility of oral-fluids collection for surveillance of porcine viruses in the Mekong Delta and to establish baseline serological and virological prevalence estimates for PRRSV, PCV2 and IAV among smallholder farms.

In the Journal of Swine Health & Production, Dr Juliet E. Bryant of the Hospital for Tropical Diseases in Ho Chi Minh City and co-authors there and at Oxford University in the UK explain that paired serum and oral-fluids samples from 68 farms (sows, boars, weaners and growers) were tested during 2011 by reverse transcriptase polymerase chain reaction and enzyme-linked immunosorbent assay for PRRSV, PCV2 and IAV.

The researchers found low numbers of PRRSV-positive and IAV-positive pigs were detected (1.6 per cent PRRSV viraemic, two of 124; 0.8 per cent IAV in oral fluids, one of 124). However, PCV2 detection rates were high in both serum and oral fluids (54.8 per cent and 61.3 per cent, respectively).

Overall proportions of pigs sero-positive for IAV and PRRSV were 37.9 and 33.9 per cent, respectively.

Proportions of pigs sero-positive for PRRSV were 48.6 per cent (17 of 35) and 12.1 per cent (four of 33) on vaccinated and unvaccinated farms, respectively.

Oral fluids and serum samples yielded comparable prevalence estimates for molecular detection of PCV2, and detected one sample PCR-positive for haemagglutinin of influenza A/H1N1/pdm09. There was no evidence of PRRSV shedding in oral fluids.

Bryant and co-authors concluded that antibody prevalence estimates based on testing oral fluids may provide an acceptable and useful surrogate for testing serum in future field studies if optimised assays are employed.


Cuong N.V., J. Carrique-Mas, H.T.V. Thu, N.D. Hien, N.T. Hoa, L.A. Nguyet, P.H. Anh and J.E. Bryant. 2014. Serological and virological surveillance for porcine reproductive and respiratory syndrome virus, porcine circovirus type 2 and influenza A viruses among smallholder swine farms of the Mekong Delta, Vietnam. J Swine Health Prod. 22(5):224–231.

Further Reading

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October 2014

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