Influenza A(H5N1) Virus Surveillance at Live Poultry Markets, Cambodia, 2011

Horm, Srey Viseth; Sorn, San; Allal, Lotfi; Buchy, Philippe

doi:10.3201/eid1902.121201

Cited by 28 publications

(41 citation statements)

References 13 publications

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“…Seasonal influenza A cases in humans peak in Cambodia during the rainy season, from June to December, whereas the majority of other influenza A cases (mainly H5N1) in humans and poultry occur during the mid/end of the dry season, from January to May (Mardy et al., ; Horm et al., ). The temporal peaks in H5N1 outbreaks in poultry and humans coincide with the releases of ducklings into rice fields in South Cambodia and the Chinese/Vietnamese and Cambodian New Year celebrations, when trading in livestock increases markedly (Burgos et al., ; Van Kerkhove et al., ; Sieng et al., ; Horm et al., , ). To enhance the possibility of detecting IAV, samples in this study were collected at the end of the dry season or beginning of the rainy season, in provinces exposed to repeated outbreaks of H5N1 in poultry and humans (OIE (World Health Organization For Animal Health), , World Health Organization, ,b).…”

Section: Discussionmentioning

confidence: 99%

“…Since 2004, Cambodia has reported 44 poultry outbreaks and 56 human cases of HP H5N1, which has led to increased active and passive influenza surveillance (World Health Organization, , OIE (World Health Organization For Animal Health, ). The active surveillance in livestock has mainly targeted detection of HP H5N1 in poultry and the surrounding environment in live bird markets (Fournié et al., ; Horm et al., , ) and serological detection of human H1N1 and H2N3 antibodies in pigs (Rith et al., ; Netrabukkana et al., ). The surveillance methods used are applicable in Cambodia since influenza vaccination is prohibited in poultry and negligible in pigs (Theary et al., ; Netrabukkana et al., ).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Influenza A Virus in Backyard Pigs and Poultry in Rural Cambodia

Osbjer

Berg

Seng

et al. 2016

Transbound Emerg Dis

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Surveillance of influenza virus in humans and livestock is critical, given the worldwide public health threats and livestock production losses. Livestock farming involving close proximity between humans, pigs and poultry is often practised by smallholders in low-income countries and is considered an important driver of influenza virus evolution. This study determined the prevalence and genetic characteristics of influenza A virus (IAV) in backyard pigs and poultry in Cambodia. A total of 751 animals were tested by matrix gene-based rRT-PCR, and influenza virus was detected in 1.5% of sampled pigs, 1.4% of chickens and 1.0% of ducks, but not in pigeons. Full-length genome sequencing confirmed triple reassortant H3N2 in all IAV-positive pigs and various low pathogenic avian influenza subtypes in poultry. Phylogenetic analysis of the swine influenza viruses revealed that these had haemagglutinin and neuraminidase genes originating from human H3N2 viruses previously isolated in South-East Asia. Phylogenetic analysis also revealed that several of the avian influenza subtypes detected were closely related to internal viral genes from highly pathogenic H5N1 and H9N2 formerly sequenced in the region. High sequence homology was likewise found with influenza A viruses circulating in pigs, poultry and wild birds in China and Vietnam, suggesting transboundary introduction and cocirculation of the various influenza subtypes. In conclusion, highly pathogenic subtypes of influenza virus seem rare in backyard poultry, but virus reassortment, involving potentially zoonotic and pandemic subtypes, appears to occur frequently in smallholder pigs and poultry. Increased targeted surveillance and monitoring of influenza circulation on smallholdings would further improve understanding of the transmission dynamics and evolution of influenza viruses in humans, pigs and poultry in the Mekong subregion and could contribute to limit the influenza burden.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Influenza A Virus in Backyard Pigs and Poultry in Rural Cambodia

Osbjer

Berg

Seng

et al. 2016

Transbound Emerg Dis

View full text Add to dashboard Cite

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“…267, 24 December 2012). Serum samples were collected, after obtaining informed consent, from LBM workers at the start of the study (January 2013) to form a baseline, and 8 weeks after the three major national festivals shown by previous work to be associated with increased A/H5N1 circulation in markets: 25 Lunar New Year, week 6; Khmer New Year, week 15; Pchum Ben, week 40. All adult-age LBM sellers or workers were exhaustively recruited in the four targeted livepoultry markets.…”

Section: Human Samplesmentioning

confidence: 99%

“…AIVs were detected throughout the year ( Figure 5), with a distinct peak of activity during January − March, perhaps mostly due to the increased circulation of A/H5N1 during major Cambodian festivals, as previously reported. 25 Longitudinal human serosurvey Successive serological surveys in the poultry worker cohort provided evidence of seroconversions and some prior exposure ( Table 2). At baseline sampling (January 2013), 125 participants were enrolled in the study, with one person testing positive to A/H5N1 antibodies and another testing positive to A/H9N2 antibodies.…”

Section: Animal and Environmental Surveillance Of A/h5n1mentioning

confidence: 99%

Intense circulation of A/H5N1 and other avian influenza viruses in Cambodian live-bird markets with serological evidence of sub-clinical human infections

Horm

Tarantola

Rith

et al. 2016

Emerging Microbes & Infections

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Surveillance for avian influenza viruses (AIVs) in poultry and environmental samples was conducted in four live-bird markets in Cambodia from January through November 2013. Through real-time RT-PCR testing, AIVs were detected in 45% of 1048 samples collected throughout the year. Detection rates ranged from 32% and 18% in duck and chicken swabs, respectively, to 75% in carcass wash water samples. Influenza A/H5N1 virus was detected in 79% of samples positive for influenza A virus and 35% of all samples collected. Sequence analysis of full-length haemagglutinin (HA) and neuraminidase (NA) genes from A/H5N1 viruses, and full-genome analysis of six representative isolates, revealed that the clade 1.1.2 reassortant virus associated with Cambodian human cases during 2013 was the only A/H5N1 virus detected during the year. However, multiplex reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of HA and NA genes revealed co-circulation of at least nine low pathogenic AIVs from HA1, HA2, HA3, HA4, HA6, HA7, HA9, HA10 and HA11 subtypes. Four repeated serological surveys were conducted throughout the year in a cohort of 125 poultry workers. Serological testing found an overall prevalence of 4.5% and 1.8% for antibodies to A/H5N1 and A/H9N2, respectively. Seroconversion rates of 3.7 and 0.9 cases per 1000 person-months participation were detected for A/H5N1 and A/H9N2, respectively. Peak AIV circulation was associated with the Lunar New Year festival. Knowledge of periods of increased circulation of avian influenza in markets should inform intervention measures such as market cleaning and closures to reduce risk of human infections and emergence of novel AIVs.

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“…Recent studies, however, have shown a >2.5-fold increase in the circulation of avian H5N1 virus in live bird markets in Cambodia during 2013 compared with 2011 ( 10 , 11 ). The peak in confirmed human infections with H5N1 reassortant virus during 2013-2014 may therefore be linked to this increased circulation of H5N1 reassortant virus among poultry, but it may also reflect improved surveillance in the public health sector because our 2014 seroprevalence study does not suggest increased transmissibility of the virus to humans.…”

Section: Discussionmentioning

confidence: 98%