European Diseases That Devastated the Americas: Smallpox, Measles, and More

Columbian Exchange: Pathogen Transfer

Post-1492, immunologically naïve Native American populations encountered Old World pathogens. Mortality estimates: 50–90% in some regions.

Major Introduced Diseases

Disease	Agent	Transmission	Impact
Smallpox	Variola virus	Respiratory, fomites	High mortality (30%+); recurrent epidemics; facilitated conquest
Measles	Measles virus	Airborne	High attack rate; pneumonia, encephalitis; synergized with malnutrition
Influenza	Influenza viruses	Respiratory	Recurrent pandemics; high mortality in naïve groups
Typhus	Rickettsia prowazekii	Body lice	Crowded conditions (mines, missions, armies)
Yellow fever	Flavivirus	Aedes mosquitoes	Caribbean, coastal cities; slave trade vector
Malaria	Plasmodium spp.	Anopheles mosquitoes	Endemic in South; shaped settlement, slavery economy
Diphtheria, pertussis, varicella	Bacteria/virus	Respiratory	High child mortality

Consequences

• Demographic collapse → labor shortage → African slave trade intensification.
• Cultural disruption, loss of traditional knowledge.
• Geopolitical reshaping (e.g., Aztec/Inca fall).

Historical Note

Intentional use (e.g., Fort Pitt blankets) documented but limited; vast majority spread unintentionally.