Clinical presentation of patients with seasonal influenza and pandemic influenza A (H1N1-2009) requiring hospitalisation.

BACKGROUND

A sudden increase in the number of novel influenza A virus (pH1N1-2009) infection prompted us to compare the clinical presentation and outcomes of patients infected with pH1N1-2009 and seasonal influenza A virus during the post-pandemic phase.

METHODS

During the period August 13 to September 27, 2010, case records of 106 patients with severe influenza like illness (ILI) and respiratory complications who underwent diagnostic testing by real-time polymerase chain reaction (RT-PCR) for confirmation of pH1N1-2009 were retrospectively studied.

RESULTS

Nineteen (17.9%) patients were tested positive for pH1N1-2009 and 78 (73.6%) were tested positive for seasonal influenza A virus. The mean age of patients infected with pH1N1-2009 was 45.2 +/- 15.3 years (range of 22 to 80 years). Common presenting symptoms included fever in 17 (89.4%), cough in 16 (84.2%), myalgia in 15 (78.9%) and breathlessness in 10 (52.6%) patients. The most common comorbidities included bronchial asthma/bronchitis/chronic obstructive pulmonary disease (COPD) in 4 (21%); followed by hypertension in 3 (15.8%) and diabetes in 3 (15.8%) patients. Overall, of the 97 influenza infected patients, 9 (9.3%) needed hospitalisation to the intensive care unit (ICU); one patient with COPD died due to multi-organ failure.

CONCLUSIONS

Both the pandemic and seasonal strains were found to be co-circulating in the community. Patients with severe hypoxia, hypertension, acute respiratory distress syndrome and shock required ICU care.