This lesson introduces germ theory and contrasts it with the older miasma theory. Understanding the difference helps explain how ideas about infection changed and why identifying the actual cause of disease matters.
The germ theory of disease is the accepted scientific explanation that infectious diseases can be caused by microorganisms known as pathogens or germs. These organisms are generally too small to see without magnification. They can enter a host, grow or reproduce there, and cause disease.
All flashcards
What did Thucydides observe about the plague of Athens?
He noted that disease could spread from an infected person to others.
What intervention did Semmelweis introduce to reduce puerperal fever?
He required doctors and medical students to wash their hands with chlorinated lime water before examining patients.
How did John Snow investigate cholera transmission in London?
He compared deaths among people supplied by different water companies and linked higher mortality to sewage-polluted water.
What do Koch’s postulates outline?
Criteria for testing whether a microorganism is causally linked to a disease.
What is an asymptomatic carrier?
A person who harbors a pathogen without showing symptoms of the disease.
Quiz questions
What term did Girolamo Fracastoro use for contaminated objects that can transmit disease?Answer: Fomites
What did Agostino Bassi conclude about muscardine in silkworms?Answer: Fungal spores transmitted the disease between caterpillars.
What did Pasteur’s swan-neck flask experiment support?Answer: Microorganisms came from external contamination rather than arising spontaneously in broth.
How did Joseph Lister apply germ-based ideas to surgery?Answer: He used carbolic acid as an antiseptic at injury sites.
Why can viruses not be grown in pure culture independently of host cells?Answer: They are obligate intracellular parasites that require host cells.