[The 2009 pandemic influenza A (H1N1) virus infection: experience of a paediatric service at a third-level hospital in Lisbon, Portugal]

INTRODUCTION

The 2009 pandemic influenza A (H1N1) (i.e., Pandemic Influenza) is an acute, infectious illness caused by the influenza A (H1N1) 2009 virus. This disease involves respiratory, gastrointestinal and systemic symptoms along with a high incidence occurring at a paediatric age.

OBJECTIVE

To study the epidemiology, approach and complications of Pandemic Influenza in the paediatric population of a third-level hospital in Lisbon, Portugal, between September and December 2009.

MATERIALS AND METHODS

A retrospective study of children who had received the influenza A (H1N1) 2009 virus test by real time reverse transcriptase-polymerase chain reaction (RT-PCR) were included. The following parameters were analysed: number of tests, days of illness, sex, outcome, age, symptoms, hospitalisation and reason for testing. The distribution and test results were compared with the Pandemic Influenza activity in Portugal. Moreover, among the confirmed cases of infection, the need for hospitalisation, risk factors, severity, chest radiography, treatment and complications were also examined.

RESULTS

A total of 351 tests were performed, on average, 2.6 days after initial symptoms, which included 71.8% outpatients and 30% children younger than three years of age. Overall, 54.4% of the tests were positive for the influenza A (H1N1) 2009 virus and the main comorbidities were respiratory and cardiovascular in nature. One hundred ninety-one cases were confirmed by laboratory studies, and 13.6% required hospitalisation, which lasted an average of 2.7 days. In 82.2% of the cases, the severity was mild, with fever and cough as the most frequent symptoms at 91.9% and 93.7%, respectively. Therapy with the antiviral drug, oseltamivir, was implemented in 35.6% of the cases. Additionally, oseltamivir was used in twelve infants younger than one year in age, including a one-month-old infant with no observed side effects.

DISCUSSION

The epidemiological data obtained are consistent with the published national and international studies. The scientific information available and the recommendations of the irectorate-General for Health contributed to the uniformity of the approaches and the successful outcome.

Clinical characteristics and outcomes among pediatric patients hospitalized with pandemic influenza A/H1N1 2009 infection

Purpose

The purpose of this article is to describe the clinical and epidemiologic features and outcomes among children hospitalized with pandemic influenza A/H1N1 2009 infection.

Methods

We retrospectively reviewed the charts of hospitalized pediatric patients (<18 years) diagnosed with pandemic influenza A/H1N1 2009 infection by reverse-transcriptase polymerase chain reaction at a tertiary hospital in Seoul, Korea, between September 2009 and February 2010.

Results

A total of 72 children were hospitalized with pandemic influenza A/H1N1 2009 infection (median age, 6.0 years; range, 2 months to 18 years). A total of 40% had at least 1 underlying medical condition, including asthma (17%), malignancies (19%), and heart diseases (17%). Of the 72 patients, 54 (76%) children admitted with H1N1 infection showed radiographic alterations compatible with pneumonia. There was no significant difference in pre-existing conditions between pandemic influenza A/H1N1 infected patients with or without pneumonia. Children with pandemic influenza A/H1N1 pneumonia were more likely to have a lower lymphocyte ratio (P=0.02), higher platelet count (P=0.02), and higher level of serum glucose (P=0.003), and more commonly presented with dyspnea than did those without pneumonia (P=0.04).

Conclusion

No significant differences in age, sex, or presence of preexisting conditions were found between children hospitalized with pandemic influenza A/H1N1 H1N1 influenza infection with pneumonia and those without pneumonia. Higher leukocyte count, higher glucose level, and a lower lymphocyte ratio were associated with the development of pandemic A/H1N1 2009 influenza pneumonia.