Enhancing global health security in Thailand: Strengths and challenges of initiating a One Health approach to avian influenza surveillance.

Infectious disease surveillance systems support early warning, promote preparedness, and inform public health response. Pathogens that have human, animal, and environmental reservoirs should be monitored through systems that incorporate a One Health approach. In 2016, Thailand's federal government piloted an avian influenza (AI) surveillance system that integrates stakeholders from human, animal, and environmental sectors, at the central level and in four provinces to monitor influenza A viruses within human, waterfowl, and poultry populations. This research aims to describe and evaluate Thailand's piloted AI surveillance system to inform strategies for strengthening and building surveillance systems relevant to One Health. We assessed this surveillance system using the United States Centers for Disease Control and Prevention's (U.S. CDC) "Guidelines for Evaluating Public Health Surveillance Systems" and added three novel metrics: transparency, interoperability, and security. In-depth key informant interviews were conducted with representatives among six Thai federal agencies and departments, the One Health coordinating unit, a corporate poultry producer, and the Thai Ministry of Public Health-U.S. CDC Collaborating Unit. Thailand's AI surveillance system demonstrated strengths in acceptability, simplicity, representativeness, and flexibility, and exhibited challenges in data quality, stability, security, interoperability, and transparency. System efforts may be strengthened through increasing laboratory integration, improving pathogen detection capabilities, implementing interoperable systems, and incorporating sustainable capacity building mechanisms. This innovative piloted surveillance system provides a strategic framework that can be used to develop, integrate, and bolster One Health surveillance approaches to combat emerging global pathogen threats and enhance global health security.

Serologic evidence of human influenza virus infections in swine populations, Cambodia.

BACKGROUND: This study was conducted from 2006 to 2010 and investigated the seroprevalence of influenza A viruses in Cambodian pigs, including human H1N1, H3N2, 2009 pandemic H1N1 (A(H1N1)pdm09), and highly pathogenic avian H5N1 influenza A viruses. METHODS: A total of 1147 sera obtained from pigs in Cambodia were tested by haemagglutination inhibition (HI) assays for antibody to human influenza A viruses along with both HI and microneutralization (MN) tests to assess immunological responses to H5N1 virus. The results were compared by year, age, and province. RESULTS: Antibodies against a human influenza A virus were detected in 14·9% of samples. A(H1N1)pdm09 virus were dominant over the study period (23·1%), followed by those to human H1N1 (17·3%) and H3N2 subtypes (9·9%). No pigs were serologically positive for avian H5 influenza viruses. The seroprevalence of human H1N1 and H3N2 influenza viruses peaked in 2008, while that of A(H1N1)pdm09 reached a peak in 2010. No significant differences in seroprevalence to human influenza subtypes were observed in different age groups. CONCLUSIONS: Cambodian pigs were exposed to human strains of influenza A viruses either prior to or during this study. The implications of these high prevalence rates imply human-to-swine influenza virus transmission in Cambodia. Although pigs are mostly raised in small non-commercial farms, our preliminary results provide evidence of sustained human influenza virus circulation in pig populations in Cambodia.

Isolation of the pandemic (H1N1) 2009 virus and its reassortant with an H3N2 swine influenza virus from healthy weaning pigs in Thailand in 2011.

A total of 300 nasal swabs were collected from 5 pig farms in two provinces in the Eastern part of Thailand in February 2011 and were subjected to viral isolation of influenza A viruses. Two H3N2 and 6 H1N1 influenza A viruses were isolated from swabs collected from clinically healthy weaning pigs on farms in Chonburi and Chachoengsao provinces, respectively. The H3N2 isolates consisted of the hemagglutinin (HA) and neuraminidase (NA) genes closely related to Thai SIVs and derived from a cluster of human seasonal H3N2 strains circulating around 1996-1997. The remaining gene segments of the isolates originated from the Pandemic (H1N1) 2009 (A (H1N1) pdm09) virus. Antigenicity of the H3N2 isolates was distinguishable from a human seasonal vaccine strain in the 1996-1998 seasons that represented antigenicity of the seasonal strains around 1996-1998. Nasal swabs from a Chachoengsao farm yielded A (H1N1) pdm09 viruses in chicken embryonated eggs and MDCK cells. A (H1N1) pdm09 viruses isolated in this study grew poorly in MDCK cells. Deduced amino acid sequences of the HA1 region of the HA protein of egg isolated viruses were identical to the sequences directly amplified from original swab samples. Our result demonstrated that the A (H1N1) pdm09 virus has been established in the Thai pig population and this has resulted in genetic reassortment with Thai SIV that previously circulated among pigs.