title: Phylogenetic Exploration of Nosocomial Transmission Chains of 2009 Influenza A/H1N1 among Children Admitted at Red Cross War Memorial Children's Hospital, Cape Town, South Africa in 2011.
abstract: Traditional modes of investigating influenza nosocomial transmission have entailed a combination of confirmatory molecular diagnostic testing and epidemiological investigation. Common hospital-acquired infections like influenza require a discerning ability to distinguish between viral isolates to accurately identify patient transmission chains. We assessed whether influenza hemagglutinin sequence phylogenies can be used to enrich epidemiological data when investigating the extent of nosocomial transmission over a four-month period within a paediatric Hospital in Cape Town South Africa. Possible transmission chains/channels were initially determined through basic patient admission data combined with Maximum likelihood and time-scaled Bayesian phylogenetic analyses. These analyses suggested that most instances of potential hospital-acquired infections resulted from multiple introductions of Influenza A into the hospital, which included instances where virus hemagglutinin sequences were identical between different patients. Furthermore, a general inability to establish epidemiological transmission linkage of patients/viral isolates implied that identified isolates could have originated from asymptomatic hospital patients, visitors or hospital staff. In contrast, a traditional epidemiological investigation that used no viral phylogenetic analyses, based on patient co-admission into specific wards during a particular time-frame, suggested that multiple hospital acquired infection instances may have stemmed from a limited number of identifiable index viral isolates/patients. This traditional epidemiological analysis by itself could incorrectly suggest linkage between unrelated cases, underestimate the number of unique infections and may overlook the possible diffuse nature of hospital transmission, which was suggested by sequencing data to be caused by multiple unique introductions of influenza A isolates into individual hospital wards. We have demonstrated a functional role for viral sequence data in nosocomial transmission investigation through its ability to enrich traditional, non-molecular observational epidemiological investigation by teasing out possible transmission pathways and working toward more accurately enumerating the number of possible transmission events.
authors.affiliation: Centre for Respiratory Diseases and Meningitis, Virology, National Institute for Communicable Diseases, Sandringham, Johannesburg, South Africa.|University of Cape Town, Faculty of Health Sciences, Department of Clinical Laboratory Sciences Medical Virology, Observatory, Cape Town, South Africa.
authors.forename: Ziyaad
authors.initials: Z
authors.lastname: Valley-Omar
authors.affiliation: University of Cape Town, Faculty of Health Sciences, Institute of Infectious Disease and Molecular Medicine, Computational Biology Group, Observatory, Cape Town, South Africa.
authors.forename: Fredrick
authors.initials: F
authors.lastname: Nindo
authors.affiliation: Centre for Tuberculosis, National Institute for Communicable Diseases, Sandringham, Johannesburg, South Africa.
authors.forename: Maanda
authors.initials: M
authors.lastname: Mudau
authors.affiliation: University of Cape Town, Faculty of Health Sciences, Department of Clinical Laboratory Sciences Medical Virology, Observatory, Cape Town, South Africa.|National Health Laboratory Service, Groote Schuur Complex, Department of Clinical Virology, Observatory, Cape Town, South Africa.
authors.forename: Marvin
authors.initials: M
authors.lastname: Hsiao
authors.affiliation: University of Cape Town, Faculty of Health Sciences, Institute of Infectious Disease and Molecular Medicine, Computational Biology Group, Observatory, Cape Town, South Africa.
authors.forename: Darren Patrick
authors.initials: DP
authors.lastname: Martin
mesh_terms: D001483:Base Sequence; D001499:Bayes Theorem; D002648:Child; D003428:Cross Infection / Q000453:epidemiology / Q000635:transmission* / Q000821:virology*; D006776:Hospitals, Pediatric; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000235:genetics* / Q000302:isolation & purification; D007251:Influenza, Human / Q000453:epidemiology / Q000635:transmission* / Q000821:virology*; D008969:Molecular Sequence Data; D010802:Phylogeny; D013019:South Africa / Q000453:epidemiology