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Emergence of Highly Pathogenic PRRS in Medium-scale Swine Farms in Cambodia

10 February 2015

In the first investigation of its type, researchers have found that there is a high incidence of highly pathogenic porcine reproductive and respiratory syndrome (PRRS) in medium-scale pig farms in south-eastern Cambodia and that the first infections were on farms near a main road from Viet Nam.

Since 2006, reports from China and Viet Nam have alerted of an emergent highly pathogenic variant of porcine reproductive and respiratory syndrome virus (HP-PRRSV) in that region, reports B. Tornimbene of the Royal Veterinary College in the UK and co-authors there, with the Animal Health and Veterinary Laboratories Agency (AHVLA) and at the National Institute of Veterinary Research (NaVRI) in Phnom Penh, Cambodia.

They explain in their paper in the journal, Preventive Veterinary Medicine, that frequent occurrence of outbreaks in these countries puts Cambodian pig farms at high risk of infection but no study had been conducted to investigate the presence of HP-PRRS in Cambodian farms.

This group investigated the presence of HP-PRRS in medium-scale (semi-commercial) pig farms in the Cambodian southeastern region. Specifically, one province bordering Viet Nam (Takeo) was selected due to the concentration of most semi-commercial farms in that province.

A cross-sectional study was carried out, between July and September 2010 to assess whether the prevalence of infection in these farms was indicative of recent spread of PPRSV and to identify risk factors for infection. The number of farms to be sampled was established using methods for Lot Quality Assurance Surveys (LQAS), in order to achieve a pre-established ability to discriminate between two different prevalence settings.

The target population comprised all semi-commercial farms in Takeo province from which a random sample of 35 farms was selected. Selected farms were visited and questionnaires administered to gather information on farm characteristics and husbandry practices. Blood samples from individual pigs were collected in each of the study farms and tested for PRRSV, along with a number of other swine respiratory pathogens in order to investigate potential interactions.

The researchers found showed that the virus was already present in Takeo semi-commercial pig population (LQAS herd prevalence more than 85 per cent) at the time of sampling.

The presence of sows in the farm and farm density were significantly associated with the introduction and the presence of PRRS – but this was an unadjusted association as small sample size precluded multivariate analysis.

Spatiotemporal description of the supposed pattern of infection revealed that the first farms infected were closely located to major national and provincial roads that connect the Cambodian capital, Phnom Penh, to Viet Nam.


Tornimbene B., J.-P. Frossard, V. Chhim, S. Sorn, J. Guitian and T.W. Drew. 2015. Emergence of highly pathogenic porcine reproductive and respiratory syndrome (HP-PRRS) in medium-scale swine farms in southeastern Cambodia. Preventive Veterinary Medicine. 118:93-103.

Further Reading

You can view the full report by clicking here.
Find out more information on PRRS by clicking here.

February 2015

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