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

Horm, Srey Viseth, Tarantola, Arnaud, Rith, Sareth, Ly, Sowath, Gambaretti, Juliette, Duong, Veasna, Y, Phalla, Sorn, San, Holl, Davun, Allal, Lotfi, Kalpravidh, Wantanee, Dussart, Philippe, Horwood, Paul F., and Buchy, Philippe (2016) Intense circulation of A/H5N1 and other avian influenza viruses in Cambodian live-bird markets with serological evidence of sub-clinical human infections. Emerging Microbes & Infections, 5. e70. pp. 1-9.

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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.

Item ID: 46929
Item Type: Article (Research - C1)
ISSN: 2222-1751
Keywords: A/H5N1; A/H9N2; avian; Cambodia; influenza; live-bird markets; poultry; seroprevalence
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Funders: Food and Agriculture Organization in Cambodia (FAOC), US Department of Health and Human Services (US DHHS), World Health Organisation, Cambodia
Projects and Grants: FAOC Grant No SRO/INT/902/USA, FAOC Grant No OSRO/RAS/901/EC, US DHHS IDSEP 110011-01-00, WHO Grant No KHM-13-ESR-000137
Date Deposited: 25 Jan 2017 01:32
FoR Codes: 32 BIOMEDICAL AND CLINICAL SCIENCES > 3202 Clinical sciences > 320211 Infectious diseases @ 100%
SEO Codes: 92 HEALTH > 9201 Clinical Health (Organs, Diseases and Abnormal Conditions) > 920109 Infectious Diseases @ 100%
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