Punnaporn Netrabukkana is a PhD student at Murdoch University, Western Australia. Her PhD project has been started since 29th March 2010 through collaborations with the GREASE network, Institut Pasteur in Cambodia, Food and Agriculture Organization of the United Nations, Kasetsart University, the Department of Livestock Development, Thailand, Zoonotic Disease Collaborating Center, and National Institute of Animal Health, Thailand and Japan. The project aimed to study the epidemiology of influenza A viruses in pigs in Thailand and Cambodia.

Summary

Student’s name: Punnaporn Netrabukkana

Topic: Epidemiology of Swine influenza in Cambodia and Thailand

Started in: March 2010

Objective: To study the epidemiology of influenza A viruses in pigs in Thailand and Cambodia

Study sites: Thailand (Mukdahan, Chonburi and Chachoengsao provinces) and Cambodia

Background

In the 2009 pandemic, genes of the causative virus (A(H1N1)pdm09) originated from two different lineages of contemporary swine influenza viruses (SIV), suggesting that the virus potentially emerged from pigs. That has emphasized the role of pigs as a “mixing vessel” for influenza viruses of different sources, facilitating genetic reassortment between viruses and avian-to-human virus adaptation.

Project summary

In Thailand, pig production systems of smallholders and trading activities in Mukdahan province were examined in order to qualitatively evaluate the potential risks that may contribute to the spread of Influenza A viruses. The study on knowledge, attitudes, and practices (KAP) towards influenza A viruses among rural pig farmers were developed in order to refine current control strategies adapted to the local context. Serological and virological surveys of influenza A viruses in pigs in Mukdahan were conducted. Additionally, studies on influenza A viruses in pigs from commercial farms were carried out in Chonburi and Chachoengsao provinces, Thailand.

In Cambodia, serological surveillance for influenza viruses was conducted in pigs for the detection of antibodies against human H1N1, human H3N2, human A(H1N1)pdm09, and avian H5N1 viruses. The data of seroprevalence to human influenza viruses in pigs in Cambodia were further analyzed in order to improve the understanding of factors underlying the spread of human influenza viruses in Cambodian pigs.

Main findings

These studies provided a better understanding of farmers’ and traders’ practices that may constitute substantial risks for interspecies influenza virus transmission in small farms of rural Thailand. Data showed that a high number of respondents had no detailed understanding of swine influenza and did not know that A(H1N1)pdm09 virus can be transmitted to pigs. This has substantial implications for public health educators and planners in implementing pandemic preparedness plans. There were no positive samples from pigs in Mukdahan, whereas 8 influenza viruses were isolated from weaning pigs in Chonburi and Chachoengsao. The study in Cambodia provided evidence of sustained human influenza virus circulation within pig populations. It demonstrated that seasonal H1, H3, and A(H1N1)pdm09 subtypes were common in Cambodian pigs, while infection with the H5 subtype was not detected.