Seroprevalence and Transmission of Human Influenza A(H5N1) Virus before and after Virus Reassortment, Cambodia, 2006–2014

Ly, Sowath; Horwood, Paul F.; Chan, Malen; Rith, Sareth; Sorn, Sopheak; Oeung, Kunthea; Nguon, Kunthy; Chan, Siam; Phalla, Y; Parry, Amy Elizabeth; Tsuyuoka, Reiko; Ly, Sovann; Richner, Beat; Laurent, Denis; Vong, Sirenda; Dussart, Philippe; Buchy, Philippe; Tarantola, Arnaud

doi:10.3201/eid2302.161232

Cited by 14 publications

(8 citation statements)

References 12 publications

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“…35 For instance, there are reports of the emergence of the new clade 1.1.2 and 2.3.2.1 reassortant A(H5N1) virus and clade 3c.2a and 3c.3a A(H3N2) virus between 2012-2015. 15,17 Within this same period, other new reassortant clades were detected for influenza A (H3N2) and B viruses in Laos PDR, Taiwan, Malaysia, Myanmar, Thailand, Japan, China and Vietnam. 35,36 The finding implies that there is the need for a sustained approach in the regions periodic update of information provided to the WHO global influenza surveillance response (GISRS) system which is a mechanism designed by the WHO for deciding the antigenic and genetic composition of influenza vaccines used in the different hemispheric zones.…”

Section: Epidemiology Seasonal Patterns and Viral Types/subtypesmentioning

confidence: 87%

“…Ever since the first influenza pandemic was reported in the 1580s, two of the three recent pandemics including the 1918 Spanish flu have originated from Asia which houses 60% of the world's population. 1,3,4,12,[14][15][16] The most recent pandemic caused by the novel influenza A virus strain A(H1N1) pdm09 which started in 2009 originated from Mexico and America and later spread to over 214 countries including South-East and East Asia causing over 18,449 deaths globally. 1,3,4,16,17 Surveillance data has shown influenza rates of 11-26% in out-patient and 6-14% in hospitalized patients in both regions.…”

Section: Epidemiology Seasonal Patterns and Viral Types/subtypesmentioning

confidence: 99%

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Human influenza viruses in South-East and East Asia: a systematic review of seasonal patterns, viral types/subtypes, and antiviral susceptibility pattern in the past two decades

Iribhogbe

Samuel

Ohaju-Obodo

2020

Int J Basic Clin Pharmacol

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The study aims to evaluate influenza seasonality pattern and identify influenza viral types/subtype as well as their antiviral susceptibility pattern in South-East (SE) and East Asia (E-Asia) with the view of providing useful information for public health action. The study is a systematic review of existing literature involving the use of search engines such as Google Scholar, PubMed and EBSCOHOST. The search was conducted using a multi-stage approach which yielded 66 articles after screening for relevance to the subject using specific inclusion and exclusion criteria. A total of 60 articles were eventually analyzed and the findings were presented in tables and bar charts. The study showed that the influenza virus was more prevalent in the 6-20 years age group (SE: 53.3% and E-Asia: 44.8%) and also occurred commonly in the age of 61-90 years age group (SE: 15.6% and E-Asia: 24.1%). Seasonal peaks were reported more in the winter period with influenza A (H1N1) pdm09 (22.37%; 24.14%), seasonal influenza A (H1N1) (6.58%; 17.24%), A (H3N2) (11.84%; 17.24%), and influenza B Victoria/Yamagata (5.26%; 20.69%) being the predominant viral type/subtypes. The pathogenic avian influenza strains; AH5N1 (7.89%) and A (H7N9) (6.90%) was also reported in SE and E-Asia respectively. Oseltamivir (37.5%) and peramivir (37.04%) were the most frequently used anti-influenza agents in SE and E-Asia respectively. However, an H55Y+I436N combined mutation 4 (12.5%) and an H274Y amino acid substitution 5 (18.5%) in the neuraminidase gene of influenza A (H1N1) pdm09 was associated with decreased sensitivity to neuraminidase inhibitors. The study has shown that influenza A (H1N1) pandemic and seasonal strain, A (H3N2), and B Victoria/Yamagata remains the predominant circulating virus in SE and E-Asia. However, the dynamic antigenic and genetic evolution of the virus calls for more frequent surveillance in the region.

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Section: Epidemiology Seasonal Patterns and Viral Types/subtypesmentioning

confidence: 87%

Section: Epidemiology Seasonal Patterns and Viral Types/subtypesmentioning

confidence: 99%

Human influenza viruses in South-East and East Asia: a systematic review of seasonal patterns, viral types/subtypes, and antiviral susceptibility pattern in the past two decades

Iribhogbe

Samuel

Ohaju-Obodo

2020

Int J Basic Clin Pharmacol

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“…This novel reassortant caused outbreaks in poultry as well as several human cases in both countries. In Cambodia the emergence of this virus was associated with a dramatic increase in human cases during 2013 and early 2014 [26].…”

Section: Gene; Viruses In Southern China With An A(h5n1) Pb1 Gene; Anmentioning

confidence: 99%

Influenza A(H5N1) viruses with A(H9N2) single gene (matrix or PB1) reassortment isolated from Cambodian live bird markets

et al. 2018

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Live bird market surveillance for avian influenza viruses in Cambodia in 2015 has led to the detection of two 7:1 reassortant influenza A(H5N1) clade 2.3.2.1c viruses. These reassortant strains, designated A/duck/Cambodia/Z564W35M1/2015 and A/chicken/Cambodia/Z850W49M1/2015, both contained a single gene (PB1 and matrix gene, respectively) from concurrently circulating A(H9N2) influenza viruses. All other viral genes from both isolates clustered with A(H5N1) clade 2.3.2.1 viruses. Continued and prolonged co-circulation of influenza A(H5N1) and A(H9N2) viruses in Cambodian live bird markets may present a risk for the emergence of novel influenza reassortant viruses with negative agricultural and/or public health implications.

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“…This virus contained the HA and neuraminidase (NA) genes from the previously circulating subclade 1.1.2 viruses and internal genes from clade 2.3.2.1a virus [10]. A dramatic increase in cases of A/H5N1 in humans in Cambodia coincided with the emergence of this reassortant strain, resulting in 26 cases in humans during 2013 and a further 8 cases in the first 3 months of 2014 [12]. The reassortant virus was subsequently replaced by clade 2.3.2.1c viruses in March 2014 and has not been detected since.…”

Section: Introductionmentioning

confidence: 99%

Transmission experiments support clade-level differences in the transmission and pathogenicity of Cambodian influenza A/H5N1 viruses

Horwood

Fabrizio

Horm

et al. 2020

Emerging Microbes & Infections

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Influenza A/H5N1 has circulated in Asia since 2003 and is now enzootic in many countries in that region. In Cambodia, the virus has circulated since 2004 and has intermittently infected humans. During this period, we have noted differences in the rate of infections in humans, potentially associated with the circulation of different viral clades. In particular, a reassortant clade 1.1.2 virus emerged in early 2013 and was associated with a dramatic increase in infections of humans (34 cases) until it was replaced by a clade 2.3.2.1c virus in early 2014. In contrast, only one infection of a human has been reported in the 6 years since the clade 2.3.2.1c virus became the dominant circulating virus. We selected three viruses to represent the main viral clades that have circulated in Cambodia (clade 1.1.2, clade 1.1.2 reassortant, and clade 2.3.2.1c), and we conducted experiments to assess the virulence and transmissibility of these viruses in avian (chicken, duck) and mammalian (ferret) models. Our results suggest that the clade 2.3.2.1c virus is more "avian-like," with high virulence in both ducks and chickens, but there is no evidence of aerosol transmission of the virus from ducks to ferrets. In contrast, the two clade 1 viruses were less virulent in experimentally infected and contact ducks. However, evidence of chicken-to-ferret aerosol transmission was observed for both clade 1 viruses. The transmission experiments provide insights into clade-level differences that might explain the variation in A/H5N1 infections of humans observed in Cambodia and other settings.

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Seroprevalence and Transmission of Human Influenza A(H5N1) Virus before and after Virus Reassortment, Cambodia, 2006–2014

Cited by 14 publications

References 12 publications

Human influenza viruses in South-East and East Asia: a systematic review of seasonal patterns, viral types/subtypes, and antiviral susceptibility pattern in the past two decades

Human influenza viruses in South-East and East Asia: a systematic review of seasonal patterns, viral types/subtypes, and antiviral susceptibility pattern in the past two decades

Influenza A(H5N1) viruses with A(H9N2) single gene (matrix or PB1) reassortment isolated from Cambodian live bird markets

Transmission experiments support clade-level differences in the transmission and pathogenicity of Cambodian influenza A/H5N1 viruses

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