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ObjectivesInterpreting real-time reverse transcription-polymerase chain reaction (rRT-PCR) results for human avian influenza A virus (AIV) detection in contaminated settings like live bird markets (LBMs) without serology or viral culture poses a challenge.MethodsDuring February-March 2012 and November 2012-February 2013, we screened workers at nine LBMs in Dhaka, Bangladesh, to confirm molecular detections of AIV RNA in respiratory specimens with serology. We tested nasopharyngeal (NP) and throat swabs from workers with influenza-like illness (ILI) and NP, throat, and arm swabs from asymptomatic workers for influenza virus by rRT-PCR and sera for seroconversion and antibodies against HPAI A(H5N1) and A(H9N2) viruses.ResultsAmong 1273 ILI cases, 34 (2.6%) had A(H5), 56 (4%) had A(H9), and six (0.4%) had both A(H5) and A(H9) detected by rRT-PCR. Of 192 asymptomatic workers, A(H5) was detected in eight (4%) NP and 38 (20%) arm swabs. Of 28 ILI cases with A(H5) or A(H9) detected, none had evidence of seroconversion, but one (3.5%) and 12 (43%) were seropositive for A(H5) and A(H9), respectively.ConclusionDetection of AIV RNA in respiratory specimens from symptomatic and asymptomatic LBM workers without evidence of seroconversion or virus isolation suggests environmental contamination, emphasizing caution in interpreting rRT-PCR results in high viral load settings.

Original publication

DOI

10.1016/j.ijid.2023.08.020

Type

Journal article

Journal

International journal of infectious diseases : IJID : official publication of the International Society for Infectious Diseases

Publication Date

11/2023

Volume

136

Pages

22 - 28

Addresses

International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh. Electronic address: zhassan@icddrb.org.

Keywords

Animals, Chickens, Humans, RNA, Bangladesh, Influenza A Virus, H5N1 Subtype, Influenza in Birds, Influenza A Virus, H9N2 Subtype