Molecular and serological investigations of the Influenza A(H1N1) 2009 pandemic virus in Turkey.

Intense research has been conducted on influenza A(H1N1)pdm09 virus to determine the virulence markers. Limited information on characteristics of pandemic virus has become available in Turkey since the pandemic. In this first report from Turkey, we investigated the molecular markers that have been associated with increased virulence and oseltamivir resistance. We also conducted serological studies in people after infection, vaccination, exposure, and no-exposure controls to determine the level of protection against the pandemic H1N1 influenza virus. Thirteen rRT-PCR positive samples were analyzed for presence of mutations that have been associated with host range, virulence, and antiviral resistance: substitution D222G in the HA, E627K in the PB2, and H275Y in the neuraminidase (NA). In addition, 135 serum samples from vaccinated, recovered, asymptomatic contacts, and control individuals were tested using hemagglutination inhibition (HI) assay. D222G was detected in nasal samples from two severe cases. No specified mutations in the PB2 and NA were identified. Additional substitutions, I216V, V321I, E374K, S203T in HA, V655I in PB2, and I163V in NA, were detected. HI testing from vaccinated individuals, recovered patients, asymptomatic contacts, and control individuals showed that 97.9, 99.7, 88.2, and 44.2 % had HI titers ≥40, respectively. Molecular markers promoting influenza A(H1N1)pdm09 to become a pandemic virus are still under investigation. Serological results confirm that younger, un-exposed individuals are at increased risk of pandemic virus infections. Influenza A(H1N1)pdm09 viruses are still in circulation around the globe. Therefore, these viruses need to be monitored closely for development of new markers including antiviral resistance mutations.

Clinical and epidemiological characteristics of pandemic influenza A/(H1N1) in hospitalized pediatric patients at a university hospital, Istanbul, Turkey.

BACKGROUND: The aim of this study was to describe the clinical and epidemiological characteristics of pandemic influenza in hospitalized children. METHODS: A total of 114 patients with suspected H1N1 virus infection were hospitalized, and nasal swabs were sent to National Influenza Reference Laboratory for confirmation of pandemic influenza A (H1N1) virus infection by rRT-PCR assay. RESULTS: Forty-six female and 68 male patients were included in the study. Age of the patients ranged from 40 days to 16 years. Clinical and/or radiological pneumonia were detected in 96% of all. Sixteen patients required mechanical ventilation due to hypoxemia. Previously healthy children required mechanical ventilation and oxygen therapy more than patients with chronic diseases. Elevated levels of CRP and LDH in patients with respiratory distress and patients who required mechanical ventilation were statistically significant. CONCLUSION: Our study showed that progress of pandemic influenza infection in previously healthy children is as severe as their counterparts with chronic underlying diseases.

Sensitivity of rapid influenza antigen tests in the diagnosis of pandemic (H1N1)2009 compared with the standard rRT-PCR technique during the 2009 pandemic in Turkey.

The real-time reverse transcription polymerase chain reaction (rRT-PCR) technique has been used as the reference technique for the diagnosis of pandemic (H1N1)2009 virus infections. However, rapid influenza diagnostics tests (RIDTs) have been considered in the diagnosis of pandemic (H1N1)2009 by some healthcare institutions in Turkey due to their ease of use and generation of fast results. Nevertheless, their low sensitivity has caused concern during the control of the pandemic. This study aimed to determine the sensitivity of 4 different rapid tests available on the market in Turkey in the diagnosis of pandemic (H1N1)2009 infections compared to the reference rRT-PCR technique. One hundred and four patient samples that tested positive and 88 samples that tested negative for pandemic (H1N1)2009 by rRT-PCR were tested with RIDTs available on the market. The sensitivity of the rapid tests ranged from 31.7% to 50% depending on the brand of RIDT. Specificity ranged from 97.7% to 100%. Currently available RIDTs are not sensitive enough and could lead physicians to delay the treatment of patients, adversely affecting control efforts to mitigate the pandemic. Therefore, these tests should only be used for screening, and negative results should not rule out influenza. More sensitive and rapid point-of-care techniques are needed to meet the demands of point-of-care testing.