Clinical manifestations of influenza caused by A/H1N1v virus among children and teenagers consulted in general practice

BACKGROUND: Children and young adults are more susceptible to pandemic A/H1N1v infection than older people. There are some publications concerning the course of the pandemic influenza among pediatric population but mostly from hospital or from emergency units. There are very few observations of the course of pandemic influenza from primary care settings. OBJECTIVE: The aim of the study was to describe clinical manifestations of influenza caused by a pandemic strain A/H1N1v among children and teenagers younger than 14 years who were observed, diagnosed, and treated in general practice. MATERIAL AND METHODS: The observations were conducted among patients with symptoms of an acute respiratory tract infection in an urban area of Warsaw, Poland in November 2009. The inclusion criteria for performing a rapid influenza diagnostic test (RIDT) were established using the CDC definition of 'influenza-like illness' (ILI): fever > 38.7°C plus cough and/or sore throat in the absence of another known cause of illness. In patients who met ILI criteria, nasopharyngeal swabs were taken for RIDT and RT-PCR. RESULTS: 433 patients were consulted by a general practitioner and reported symptoms of an acute respiratory tract infection, 128 (30%) of them met inclusion criteria for ILI and were tested with RIDT: 31 children younger than 14 years and 97 adults. All 31 children suspected of ILI also were tested by RT-PCR. 20 children had a positive result of the rapid influenza test. For all children tested negative, RT-PCR was also negative, and out of 20 children with the presumptive diagnosis of influenza established after rapid influenza test, the diagnosis was confirmed by RT-PCR in 18; their median age was 6.6 years and ranged from13 months to 14 years. The most common symptoms of influenza A/H1N1v were: high fever (> 39°C) -96% of patients, dry cough - 86% of patients, malaise - 78% of patients, headache - 66% of patients, and diarrhea or vomiting - 28% of patients. Two children received treatment with oseltamivir (one boy with congenital heart defect and Down's syndrome and another with severe bronchial asthma). The duration of symptoms ranged from 1 to 13 days (mean of 6.6 days). No patients required hospitalization either due to primary influenza infection or secondary complications. CONCLUSIONS: The course of influenza caused by virus A/H1N1v in children younger than 14 years observed in a primary care setting was mild and self-limited without the necessity of antiviral treatment in most cases. A rapid influenza diagnostic test is helpful in diagnosing pandemic influenza.