Viral Shedding in University Students Infected by Influenza A (H1N1) pdm09, Nakhon Ratchasima Province, Thailand, June 2011
Keywords:
Influenza A (H1N1) pdm09, viral shedding, outbreak, university, ThailandAbstract
Background: Since June 2009, a numerous school outbreaks of Influenza A (H1N1) pdm09 in Thailand had been reported. Nevertheless, the knowledge of the viral shedding of Influenza A (H1N1) pdm09 among young adult and received antivirals treatment patients remains limited. On May 30, 2011, Influenza A (H1N1) pdm09 outbreak was detected in University S, Nakhon Ratchasima Province. An investigation was conducted to describe characteristics of H1N1 viral shedding and immunologic response in the infected students during epidemic in the university, and to identify factors affecting viral shedding.
Methods: A descriptive study was performed. We enrolled acute respiratory illness (ARI) patients who went to a medical center at University S and had laboratory-confirmed influenza A (H1N1) pdm09 infection by realtime RT-PCR during June 3 – 7, 2011. Throat swabs were collected and tested by real-time RT-PCR daily after the first specimen performed until the result became negative for 2 consecutive days. Moreover, serum samples for hemagglutination inhibition (HI) test were collected on enrollment day (day 0), day 7, 14, 28 and 90, respectively. This study was approved by the Ethics Committee of Ministry of Public Health in Thailand.
Results: Of 29 enrolled patients, all were university students. The female: male was 1.2:1 and median age was 20 years (IQR: 19-21 years). All were prescribed Oseltamivir and nobody was hospitalized. Median duration of viral shedding detected by real-time RT-PCR was 5 days (range: 3-9 days). More than 80% of the patients had 4-fold rise of HI titer within 2-3 weeks after symptoms onset. Those who had BMI ≥ 23 kg/m2, underlying allergy or got fever tend to have longer duration of viral shedding; however, statistically insignificant.
Conclusions: Influenza A (H1N1) pdm09 viral shedding duration among patients treated with Oseltamivir in this university was approximately 5 days and compatible with findings of other studies reported 4-6 days in adult populations. This study demonstrated the benefit of early antiviral treatment in preventing severe outcome of influenza A (H1N1) pdm09 infections and shorten the viral shedding time.
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