Influenza

Influenza
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Influenza virus
Synonyms	flu, grippe (French for flu)
Specialty	Infectious disease
Symptoms	Fever, runny nose, sore throat, muscle pain, headache, coughing, fatigue
Usual onset	1–4 days after exposure
Duration	2–8 days
Causes	Influenza viruses
Prevention	Hand washing, flu vaccines
Medication	Antiviral drugs such as oseltamivir
Frequency	3–5 million severe cases per year
Deaths	>290,000–650,000 deaths per year

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Influenza, colloquially known as the flu, is an infectious disease caused by the influenza virus. It spreads around the world in yearly outbreaks, resulting in about three to five million cases of severe illness and about 290,000 to 650,000 deaths

Introduction

Influenza viruses circulate in every part of the world. Type A influenza virus is the most dangerous, as it can cause severe disease and trigger pandemics. Influenza B can cause outbreaks but is usually less severe than type A. Influenza C typically causes mild illness in children.

Symptoms

Influenza is characterized by sudden onset of high fever, cough (usually dry), headache, muscle and joint pain, severe malaise (feeling unwell), sore throat, and a runny nose. Most people recover from fever and other symptoms within a week without requiring medical attention. But influenza can cause severe illness or death in people at high risk.

Transmission

The virus is transmitted easily from person to person via droplets and small particles produced when infected people cough or sneeze. Influenza virus may also be spread by direct or indirect contact with respiratory droplets from infected individuals.

Prevention

Immunization with a yearly influenza vaccination is the most effective way to prevent the flu. Antiviral drugs are also available and can reduce severe outcomes, but they are not a substitute for vaccination.

Treatment

Antiviral drugs can treat influenza and are a second line of defense against complications. But these drugs need to be administered early (within 48 hours after symptom onset) and they may not be effective against all types of influenza virus.

Impact

Influenza epidemics can severely affect the economy due to lost workforce productivity, extra healthcare costs, and strained healthcare services. In addition, pandemics can cause widespread illness and death, such as the 1918 Spanish flu pandemic, which is estimated to have caused 20-50 million deaths worldwide.

See also

• Glossary of Influenza related terms
• Influenza vaccine
• Influenza pandemic
• Avian influenza
• Swine influenza