Spanish Flu (1918–1920): Causes, Symptoms, and Impact

Overview

The 1918 influenza pandemic (Spanish Flu) infected ~1/3 of the global population, killing 50–100 million. One of the deadliest pandemics in history.

Origins

Likely emerged spring 1918 in the U.S.; spread rapidly through WWI military camps.

Characteristics

Caused by virulent H1N1 influenza A. Unusually targeted healthy adults 20–40 years old.

Symptoms and Complications

Fever, chills, muscle aches, severe headaches, pneumonia, respiratory distress. Bacterial pneumonia often led to death.

Spread

Global troop movements, lack of vaccines, poor hygiene, crowded cities fueled transmission.

Impact

Overwhelmed healthcare, disrupted public services, severe economic damage.

End and Lessons

Declined by mid-1919; milder wave later. Spurred advances in public health, surveillance, vaccines. Lessons guide current pandemic responses.