First Pandemic (1817–1824)

Transmission routes: Trade routes across India, Southeast Asia, Middle East.

Key developments: First global expansion beyond South Asia.

Second Pandemic (1829–1837)

Key developments: Arrival in Europe (1831–32).

Third Pandemic (1846–1860)

Key developments: Peak global mortality; John Snow's investigations.

Fourth Pandemic (1863–1875)

Key developments: Steamship expansion accelerates spread.