definitions

1. A few important definition for
Public Health related courses
Provided by Dr. Claudia Madampage

2. Epidemic and Pandemic
• Epidemic: Occurrence of a disease clearly in excess of normal expectancy.
Examples: The cholera epidemic in 1854 in London.
The measles outbreak in 2019 in New Zealand
The Kivu Ebola epidemic in the Democratic Republic of the
Congo and Uganda in 2018-2020
• Pandemic: An epidemic that spans a wide geographic area.
Examples: The 1918 influenza pandemic ('Spanish flu’)
The current Covid-19 worldwide pandemic
2
Robert H. Friis and Thomas A. Sellers. Epidemiology for public health practice, Fifth edition (2014)

3. Zoonotic
• Zoonotic means infectious diseases of
animals that are spread to humans by ticks,
mosquitoes, or fleas or contact with
animals.
• These diseases include:
• Lyme disease (spread by ticks).
• West Nile virus disease
(spread by mosquitoes).
• Rabies (spread by raccoons, skunks,
bats, and other mammals).
Emerging and Zoonotic Infectious Diseases. Centers for Disease controls and prevention. National center for emerging and zoonotic infectious diseases.
https://www.cdc.gov/ncezid/pdf/ncezid_brochure_2012.pdf
Figure: Petersen E, Petrosillo N, Koopmans M; ESCMID Emerging Infections Task Force Expert Panel. Emerging infections-an increasingly important topic: review by the Emerging
Infections Task Force. Clin Microbiol Infect. 2018 Apr;24(4):369-375. doi: 10.1016/j.cmi.2017.10.035. Epub 2017 Nov 15. PMID: 29155018; PMCID: PMC7129920.
Figure : Illustration of five stages through which pathogens of animals
evolve to cause diseases confined to humans

4. Infectious Diseases (ID)
• Pathogens have been a significant cause of human illness. These
illnesses known as infectious diseases (ID) caused by pathogens
(bacteria, viruses, fungi etc.) first enter the human host (the body),
multiply, and cause an infection.

5. Sanitary Idea
• Epidemics are a major cause of death
• Cholera and Typhoid
• Competing theories
• Miasma theory: Disease is caused by inhaling bad smells from filth
• Germ theory: Pathogens in the air or water cause disease

6. Contagion
• Fracastoro defined a contagion as a "corruption which develops in the
substance of a combination, passes from one thing to another, and is
originally caused by infection of the imperceptible particles"
(Fracastorius, 1930, p. 5.).
• He called the particles the seminaria (seeds or seedlets) of contagion.
(I translate Fracastoro's "seminaria" as "seeds" rather than the
customary but anachronistic "germs".)
Taken word-to word from: Paul Thagard. http://cogsci.uwaterloo.ca/Articles/Pages/Concept.html

7. John Snow
• Cholera epidemic in Soho, London
• Father of epidemiology
• Counted exposure to water and cases of disease
• Removed the handle on the broad street pump: Intervention
• Cholera: Discovered after the removal of the pump (by Robert Koch)