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

Abstract

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.

Human influenza viruses in South-East and East Asia: a systematic review of seasonal patterns, viral types/subtypes, and antiviral susceptibility pattern in the past two decades

“…1,3 Research has shown that nineteen of the genetically distinct types have shown reassortment since the 1918 Spanish flu which ravaged the world and claimed over 20-50 million lives globally. 1,4 Additionally, six strains of the genetically distinct subtypes are known to have human-to-human transmission, ten are zoonotic avian influenza viruses while three are zoonotic swine influenza viruses. 1,3,4 However, in the past five years, four novel influenza subtypes and three novel strains of the virus have emerged in humans.…”

“…1,4 Additionally, six strains of the genetically distinct subtypes are known to have human-to-human transmission, ten are zoonotic avian influenza viruses while three are zoonotic swine influenza viruses. 1,3,4 However, in the past five years, four novel influenza subtypes and three novel strains of the virus have emerged in humans. [1][2][3][4] Although fourteen different HA-NA combinations are known to cause human infections, studies have shown that Influenza H1N1, H1N2, and H3N2 HA-NA combinations have emerged multiple times since the Spanish flu pandemic that ravaged the world in 1918.…”

“…1,3,4 However, in the past five years, four novel influenza subtypes and three novel strains of the virus have emerged in humans. [1][2][3][4] Although fourteen different HA-NA combinations are known to cause human infections, studies have shown that Influenza H1N1, H1N2, and H3N2 HA-NA combinations have emerged multiple times since the Spanish flu pandemic that ravaged the world in 1918. [1][2][3] Influenza has continued to be a major cause of morbidity and mortality that is difficult to ignore despite the current global COVID-19 pandemic.…”

“…The World Health Organization estimates that it is responsible for over 500,000 deaths annually and over 1 billion people are infected with the virus. 1,4,5 Influenza viruses that are commonly implicated in humans include; influenza A (H1N1) pdm 09, influenza A (H3N2), and influenza B which has two strains Victoria and Yamagata. [1][2][3][6][7][8] The virus causes an acute respiratory tract infection (flu) and has an incubation period that ranges from 1-4 days.…”

Influenza H1 Mosaic Hemagglutinin Vaccine Induces Broad Immunity and Protection in Mice

“…Annually, influenza A virus (IAV) infects~5-10% of adults and 20-30% of children worldwide, resulting in up to 650,000 deaths each year [1][2][3]. The ability of IAV to mutate, reassort, and infect multiple hosts results in a diverse viral population that causes annual epidemics and occasionally pandemic outbreaks.…”