Influenza

Lore & Background

Influenza is caused by four types of virus: A, B, C, and D. Influenza A virus, primarily from aquatic birds, is widespread in mammals and responsible for most severe illness and pandemics. Influenza B virus mainly infects humans and contributes to seasonal epidemics, while influenza C virus causes mild infections, mostly in children. Influenza D virus is found in cattle and pigs and can infect humans without causing illness. Transmission occurs through respiratory droplets, aerosols, and contaminated surfaces. Symptoms include fever, cough, sore throat, muscle pain, and fatigue, with gastrointestinal symptoms possible in children. The incubation period is one to four days, and symptoms last two to eight days. Complications include pneumonia, acute respiratory distress syndrome, meningitis, and encephalitis.

Reader's Guide

High-risk groups include young children, the elderly, and those with chronic health conditions. Prevention relies on frequent hand washing, mask-wearing, and annual vaccination, which is updated regularly due to the virus's rapid evolution, particularly influenza A virus. Vaccines target subtypes H1N1 and H3N2 and one or two influenza B virus subtypes. Diagnosis uses antibody or antigen tests and PCR. Treatment is supportive, with antiviral drugs like oseltamivir for severe cases. Influenza's ability to evolve and cause recurrent outbreaks underscores the need for ongoing surveillance and vaccine development.

Did You Know?

• Influenza viruses are classified into four types: A, B, C, and D.
• Aquatic birds are the primary source of influenza A virus.
• The incubation period for influenza is one to four days, most commonly one to two days.