THAILAND - Looking into the incidence of porcine reproductive and respiratory syndrome (PRRS) in different districts, scientists concluded that breeding sows should be the focus of targeted surveillance and control. They were unable to identify the highly pathogenic form of the virus, which is thought to be circulating in the country.
Following a study of PRRS in Thailand, researchers concluded that breeding sows may be an important group for targeted surveillance and control of the disease.
The spatial epidemiology of PRRS in the country was investigated by Weerapong Thanapongtharm of the Department of Livestock Development (DLD) in Bangkok and other scientists in Thailand and Belgium.
In BMC Veterinary Research recently, they reported that PRRS has become a worldwide endemic disease of pigs. In 2006, an atypical and more virulent PRRS (HP-PRRS) emerged in China and spread to many countries, including Thailand.
Their study aimed to provide a first description of the spatio-temporal pattern of PRRS in Thailand and to quantify the statistical relationship between the presence of PRRS at the sub-district level and a set of risk factors. This should provide a basis for improving disease surveillance and control of PRRS in Thailand.
Spatial scan statistics were used to detect clusters of outbreaks and allowed the identification of six spatial clusters covering 15 provinces of Thailand.
Two modelling approaches were used to relate the presence or absence of PRRS outbreaks at the sub-district level to demographic characteristics of pig farming and other epidemiological spatial variables: autologistic multiple regressions and boosted regression trees (BRT). The variables showing a statistically significant association with PRRS presence in the autologistic multiple regression model were the sub-district human population and number of farms with breeding sows.
The predictive power of the model, as measured by the area under the curve (AUC) of the receiver operating characteristics (ROC) plots was moderate. BRT models had higher goodness of fit the metrics and identified the sub-district human population and density of farms with breeding sows as important predictor variables.
Thanapongtharm and co-authors concluded that farms with breeding sows may be an important group for targeted surveillance and control. However, these findings obtained at the sub-district level should be complemented by farm-level epidemiological investigations in order to obtain a more comprehensive view of the factors affecting PRRS presence.
In this study, the outbreaks of PRRS could not be differentiated from the potential novel HP-PPRS form, which was recently discovered in the country.
Thanapongtharm W., C. Linard, N. Pamaranon, S. Kawkalong, T. Noimoh, K. Chanachai, T. Parakgamawongsa and M. Gilbert. 2014. Spatial epidemiology of porcine reproductive and respiratory syndrome in Thailand. BMC Veterinary Research. 10:174 doi:10.1186/s12917-014-0174-y
ThePigSite News Desk
Top image via Shutterstock