80 year ago in 1938, the average life expectancy for men was 61, and women lived an average 65 years. Today, the average life expectancy is 77 years for men and 81 years for women. What led to this huge increase? The credit goes to several factors, with one being scientific research and development of medication and vaccines for diseases that once wiped humans out in huge numbers. These infectious diseases changed civilization, prompted medical breakthroughs & led to scientific advancements. They also killed millions. Click To Tweet
How can something so small the naked eye can’t see it cause so much devastation? Pathogens have caused plagues and disease so widespread that the effects are felt for generations. Here are 5 terrible infectious diseases that changed the world:
- The Black Death
- 1918 Spanish Flu
1) The Black Death
The Black Death was an epidemic of bubonic plague, a disease caused by the bacterium Yersinia pestis that circulates among wild rodents where they live in high numbers. The bubonic plague demonstrated how human advancements in travel and trade could fatally spread a pathogen, carrying infected individuals, rats, and fleas via ships across the Mediterranean.
2) 1918 Spanish Flu
The H1N1 pandemic appeared in multiple countries around the world, but didn’t originate Spain. The disease spread rapidly, thanks in part to the close living quarters of troops fighting in World War I. It killed around 50 million worldwide with about 675,000 deaths occurring in the United States. The pandemic was so severe that from 1917 to 1918, life expectancy in the United States fell by about 12 years for both men and women. By 1919 it had all but disappeared, although other flu pandemics have occurred since, but none as deadly.
TB is a deadly respiratory infection caused by the organism Mycobacterium tuberculosis, It can take two forms: latent TB and active TB. Latent TB isn’t contagious, and one’s immune system can often fight it off. In fact, one-third of the world’s population has latent TB. Throughout the 1600-1800s in Europe and the United States, TB caused 25% of all deaths.
Polio is caused by one of three types of poliovirus, spread through contact between people, by nasal and oral secretions, and by contact with contaminated feces. Polio reached epidemic proportions in the early 1900s in countries with relatively high standards of living, at a time when other diseases such as diphtheria, typhoid, and tuberculosis were declining. In 1916, New York City experienced the first large epidemic of polio, with over 9,000 cases and 2,343 deaths. The 1916 toll nationwide was 27,000 cases and 6,000 deaths. Many who survived were permanently disabled or paralyzed.
Smallpox was caused by the variola virus, which plagued humanity for centuries and had a lasting impact on civilization. As late as the 1960s, smallpox was still endemic in Asia and Africa, with an estimated two million deaths occurring annually. Smallpox was spread easily between people by sneezing or shared contact, leading to disfiguring pustular lesions on the skin. The disease was severe, with 30% of affected people dying, while the rest were left with complications associated with infection.
All of these devastating diseases played a part in shaping human behavior. With scientific advancements came the knowledge of how infections were spread and what measures could prevent their reach. Acts as simple as hand washing can be attributed to insights into how infections are spread.
Microbiological research and testing is part of the reason that smallpox has been eradicated. Testing determines where and what pathogens are present, preventing people from being exposed to them.