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Epidemiology The study of the distribution of diseases.

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Presentation on theme: "Epidemiology The study of the distribution of diseases."— Presentation transcript:


2 Epidemiology The study of the distribution of diseases

3 Medical Geography The study of health from a spatial perspective Medical geography includes: The study of overall health and nutrition patterns Locational analysis (where hospitals should be built, emergency planning, GPS systems) Epidemiology "Health is a state of complete physical, mental, and social well-being, and not merely the absence of disease or infirmity." --The World Health Organization

4 Epidemiology epi = upon dem = people ology = the study of The Greek “god” of medicine was Asclepius and his staff, the caduceus, is now known as a symbol for medicine. Hippocrates, a member of the Guild of Asclepius, is known as the “Father of Medicine.”

5 Types of epidemics An epidemic is when a disease strikes many people in a population at the same time An endemic is an epidemic limited to a certain region A pandemic is a worldwide epidemic

6 Epidemiology is the study of the distribution of diseases in an attempt to: Determine the cause of the disease Determine how the disease spreads Halt the spread of disease


8 John Snow 1854 London Cholera Epidemic




12 How Diseases Spread Infectious diseases are spread by agents, disease-causing organisms Infected people or animals are called hosts If a population contains many hosts, it becomes a reservoir for the disease When a disease is spread through an intermediate host, it is called a vectored disease Non-biological vectors are called vehicles Diseases spread directly from host to host are non-vectored diseases

13 Cholera Bacterial disease (mapped by John Snow) Water and food are the vehicles Originally endemic to India until early 1800s The main reservoir for this disease is marine shellfish and plankton Causes diarrhea and dehydration Re-emerging disease that can be halted through proper sewage treatment, safe food handling, and clean water supplies 250,000+ cases in 1999 with 9,000+ deaths

14 Epidemiology is the study of the distribution of diseases in an attempt to: Determine the cause of the disease Determine how the disease spreads Halt the spread of disease

15 Environmental Impact on Disease Many diseases live only part of life-cycle within humans These diseases must be able to survive outside the human body Warm, humid environments are more conducive to disease survival As people push into tropics, they increase their risk of encountering diseases


17 Human Habits Many disease organisms spread through fecal-oral mode of transmission Sexually transmitted diseases (STDs) can be reduced or eliminated Person-to-Person contact is often transmitted through coughing or sneezing

18 E. coli Bacterium found in human and cattle excrement (and deer, goats, and sheep) Early E. coli outbreaks associated with contaminated ground meat Now associated with farm workers not having adequate bathroom facilities 60,000 yearly infections in the U.S. with a death rate of 1/1,000

19 Reduce Diffusion of Disease Cover your mouth when you cough or sneeze Wash your hands regularly when ill

20 Human Habits for Health Eat right Get exercise Avoid smoking Get enough sleep Take time to relax

21 The Bubonic Plague The Plague is a contagious disease caused by the agent bacillus, a rod-shaped bacteria, that resides in the intestines of fleas.

22 The Plague’s Hosts The primary hosts of the plague are fleas, but rodents, cats, dogs, and humans can also become intermediary hosts.

23 The Plague The plague is a vectored disease because it is spread through intermediate hosts, such as rats. The plague can become a non-vectored disease when the plague gets into the lungs.

24 Symptoms of the Plague Headaches Weakness Chills Pustules Swollen lymph nodes Bleeding under skin

25 Plague Pandemics There have been 3 pandemics, or global epidemics, during historical times.

26 The First Pandemic Resulted in people flocking to the Church Church gained power

27 The Second Pandemic Killed 1/3- 1/2 of Europe’s population, and about that same amount in the Middle East People became disenchanted with the church’s inability to halt the plague Survivors could ask for, and receive, high wages, thus ending the feudal manorial economic system

28 The Third Pandemic Began in 1855 Truly global Plague bacillus identified in 1894 Discovered in 1898 that fleas transmitted disease Cure found in the 1930s Reservoirs established in the Americas

29 World Distribution of Plague

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