History and current trends in influenza virus infections with special reference to Sri Lanka.

The World Health Organization (WHO) estimates that approximately one billion people are infected and up to 500,000 people die from influenza each year in the world. Influenza is considered to be the greatest killer of the human populations, due to the 1918 Spanish flu, which killed millions around the world. Despite the effective treatment available against influenza, it still contributes to significant morbidity and mortality. Currently circulating influenza strains in humans include influenza A (H1N1)pdm09, influenza A (H3N2) and influenza B viruses, (B/Victoria and B/Yamagata). Influenza has been prevalent in Sri Lanka from 1969, since then it continued to cause morbidity and mortality in children and adults. The current global influenza surveillance network monitors the global influenza activity through WHO collaborating centres. The Medical Research Institute monitors and diagnoses influenza cases in the country as part of the WHO network laboratories. Vaccinations to high risk groups and antiviral therapy for the successful prevention of influenza have been practiced in Sri Lanka. This review highlights the impact of influenza on public health in Sri Lanka including the historical aspects, current diagnostic practices and prevention approaches in high risk individuals in the country.