About Seasonal Influenza:
- What is it? Seasonal influenza is an acute respiratory infection caused by influenza viruses which circulate in all parts of the world.
- Cause: There are 4 types of seasonal influenza viruses, types A, B, C and D. Influenza A and B viruses circulate and cause seasonal epidemics of disease.
- Signs and symptoms: Seasonal influenza is characterized by a sudden onset of fever, cough (usually dry), headache, muscle and joint pain, severe malaise (feeling unwell), sore throat and a runny nose. But influenza can cause severe illness or death especially in people at high risk (see below).
- Timing of epidemics:
- In temperate climates, seasonal epidemics occur mainly during winter.
- In tropical regions, influenza may occur throughout the year, causing outbreaks more irregularly.
- Global scenario: WHO describes Influenza epidemics as one of the world’s greatest public health challenges. Influenza epidemics, largely seasonal, affect around one billion people and kill hundreds of thousands annually.
- List of influenza pandemics: A pandemic can arise when a new influenza virus that hasn't affected humans before emerges, spreads and causes illness in humans.
- The world has suffered through a number of devastating influenzas pandemics, including the Spanish Flu, which in 1918 killed tens of millions of people globally.
- Three pandemics have occurred since—in 1957, 1968 and in 2009—when the H1N1 swine flu pandemic claimed around 18,500 lives in 214 countries.
- According to WHO’s recent report, another influenza pandemic is inevitable, the question is when?
- In 2018, the world observed the centenary of the start of the 1918–1919 influenza pandemic.
