title: Human Sentinel Surveillance of Influenza and Other Respiratory Viral Pathogens in Border Areas of Western Cambodia.
abstract: Little is known about circulation of influenza and other respiratory viruses in remote populations along the Thai-Cambodia border in western Cambodia. We screened 586 outpatients (median age 5, range 1-77) presenting with influenza-like-illness (ILI) at 4 sentinel sites in western Cambodia between May 2010 and December 2012. Real-time reverse transcriptase (rRT) PCR for influenza was performed on combined nasal and throat specimens followed by viral culture, antigenic analysis, antiviral susceptibility testing and full genome sequencing for phylogenetic analysis. ILI-specimens negative for influenza were cultured, followed by rRT-PCR for enterovirus and rhinovirus (EV/RV) and EV71. Influenza was found in 168 cases (29%) and occurred almost exclusively in the rainy season from June to November. Isolated influenza strains had close antigenic and phylogenetic relationships, matching vaccine and circulating strains found elsewhere in Cambodia. Influenza vaccination coverage was low (<20%). Western Cambodian H1N1(2009) isolate genomes were more closely related to 10 earlier Cambodia isolates (94.4% genome conservation) than to 13 Thai isolates (75.9% genome conservation), despite sharing the majority of the amino acid changes with the Thai references. Most genes showed signatures of purifying selection. Viral culture detected only adenovirus (5.7%) and parainfluenza virus (3.8%), while non-polio enteroviruses (10.3%) were detected among 164 culture-negative samples including coxsackievirus A4, A6, A8, A9, A12, B3, B4 and echovirus E6 and E9 using nested RT-PCR methods. A single specimen of EV71 was found. Despite proximity to Thailand, influenza epidemiology of these western Cambodian isolates followed patterns observed elsewhere in Cambodia, continuing to support current vaccine and treatment recommendations from the Cambodian National Influenza Center. Amino acid mutations at non-epitope sites, particularly hemagglutinin genes, require further investigation in light of an increasingly important role of permissive mutations in influenza virus evolution. Further research about the burden of adenovirus and non-polio enteroviruses as etiologic agents in acute respiratory infections in Cambodia is also needed.
authors.affiliation: Department of Immunology, US Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand.
authors.forename: Ans
authors.initials: A
authors.lastname: Timmermans
authors.affiliation: Viral Diseases Branch, Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America.
authors.forename: Melanie C
authors.initials: MC
authors.lastname: Melendrez
authors.affiliation: Department of Immunology, Armed Forces Research Institute of Medical Sciences, Battambang, Cambodia.
authors.forename: Youry
authors.initials: Y
authors.lastname: Se
authors.affiliation: Department of Immunology, US Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand.
authors.forename: Ilin
authors.initials: I
authors.lastname: Chuang
authors.affiliation: Department of Immunology, Armed Forces Research Institute of Medical Sciences, Battambang, Cambodia.
authors.forename: Nou
authors.initials: N
authors.lastname: Samon
authors.affiliation: Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand.
authors.forename: Nichapat
authors.initials: N
authors.lastname: Uthaimongkol
authors.affiliation: Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand.
authors.forename: Chonticha
authors.initials: C
authors.lastname: Klungthong
authors.affiliation: Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand.
authors.forename: Wudtichai
authors.initials: W
authors.lastname: Manasatienkij
authors.affiliation: Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand.
authors.forename: Butsaya
authors.initials: B
authors.lastname: Thaisomboonsuk
authors.affiliation: Department of Immunology, US Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand.
authors.forename: Stuart D
authors.initials: SD
authors.lastname: Tyner
authors.affiliation: Virology Department, Institut Pasteur du Cambodge, Phnom Penh, Cambodia.
authors.forename: Sareth
authors.initials: S
authors.lastname: Rith
authors.affiliation: Virology Department, Institut Pasteur du Cambodge, Phnom Penh, Cambodia.
authors.forename: Viseth Srey
authors.initials: VS
authors.lastname: Horm
authors.affiliation: Viral Diseases Branch, Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America.
authors.forename: Richard G
authors.initials: RG
authors.lastname: Jarman
authors.affiliation: Department of Immunology, US Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand.
authors.forename: Delia
authors.initials: D
authors.lastname: Bethell
authors.affiliation: Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand.
authors.forename: Nitima
authors.initials: N
authors.lastname: Chanarat
authors.affiliation: Deputy Director, Armed Forces Health Surveillance Center, Silver Spring, Maryland, United States of America.
authors.forename: Julie
authors.initials: J
authors.lastname: Pavlin
authors.affiliation: Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand.
authors.forename: Tippa
authors.initials: T
authors.lastname: Wongstitwilairoong
authors.affiliation: Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand.
authors.forename: Piyaporn
authors.initials: P
authors.lastname: Saingam
authors.affiliation: Department of Immunology, Armed Forces Research Institute of Medical Sciences, Battambang, Cambodia.
authors.forename: But Sam
authors.initials: BS
authors.lastname: El
authors.affiliation: Department of Immunology, US Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand.
authors.forename: Mark M
authors.initials: MM
authors.lastname: Fukuda
authors.affiliation: Communicable Disease Control Department, Ministry of Health, Phnom Penh, Cambodia.
authors.forename: Sok
authors.initials: S
authors.lastname: Touch
authors.affiliation: Communicable Disease Control Department, Ministry of Health, Phnom Penh, Cambodia.
authors.forename: Ly
authors.initials: L
authors.lastname: Sovann
authors.affiliation: Department of Immunology, US Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand.
authors.forename: Stefan
authors.initials: S
authors.lastname: Fernandez
authors.affiliation: Virology Department, Institut Pasteur du Cambodge, Phnom Penh, Cambodia.
authors.forename: Philippe
authors.initials: P
authors.lastname: Buchy
authors.affiliation: Department of Immunology, Armed Forces Research Institute of Medical Sciences, Phnom Penh, Cambodia.
authors.forename: Lon
authors.initials: L
authors.lastname: Chanthap
authors.affiliation: Department of Immunology, US Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand.
authors.forename: David
authors.initials: D
authors.lastname: Saunders
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002160:Cambodia; D002648:Child; D002675:Child, Preschool; D004770:Enterovirus / Q000235:genetics*; D004769:Enterovirus Infections / Q000453:epidemiology / Q000235:genetics; D006801:Humans; D007223:Infant; D053118:Influenza A Virus, H1N1 Subtype / Q000235:genetics*; D007251:Influenza, Human / Q000453:epidemiology / Q000235:genetics; D008875:Middle Aged; D010850:Picornaviridae Infections / Q000453:epidemiology / Q000235:genetics; D012229:Rhinovirus / Q000235:genetics*; D018571:Sentinel Surveillance