EpidemiologyThe study of

the distribution of diseases

Medical Geography

The study of health from a spatial perspectiveMedical geography includes:

The study of overall health and nutrition patternsLocational 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

Epidemiologyepi = upon

dem = peopleology = 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.”

Types of epidemics

An epidemic is when a disease strikes many people in a population at the same timeAn endemic is an epidemic limited to a certain regionA pandemic is a worldwide epidemic

Epidemiology is the study of the distribution of

diseases in an attempt to:

Determine the cause of the diseaseDetermine how the disease spreadsHalt the spread of disease

John Snow1854 London

Cholera Epidemic

How Diseases SpreadInfectious diseases are spread by agents, disease-causing organismsInfected people or animals are called hostsIf a population contains many hosts, it becomes a reservoir for the diseaseWhen a disease is spread through an intermediate host, it is called a vectored diseaseNon-biological vectors are called vehiclesDiseases spread directly from host to host are non-vectored diseases

CholeraBacterial disease (mapped by John Snow)Water and food are the vehiclesOriginally endemic to India until early 1800sThe main reservoir for this disease is marine shellfish and planktonCauses diarrhea and dehydrationRe-emerging disease that can be halted through proper sewage treatment, safe food handling, and clean water supplies250,000+ cases in 1999 with 9,000+ deaths

Epidemiology is the study of the distribution of

diseases in an attempt to:

Determine the cause of the diseaseDetermine how the disease spreadsHalt the spread of disease

Environmental Impact on Disease

Many diseases live only part of life-cycle within humansThese diseases must be able to survive outside the human bodyWarm, humid environments are more conducive to disease survivalAs people push into tropics, they increase their risk of encountering diseases

Human Habits

Many disease organisms spread through fecal-oral mode of transmissionSexually transmitted diseases (STDs) can be reduced or eliminatedPerson-to-Person contact is often transmitted through coughing or sneezing

E. coliBacterium found in human and cattle excrement (and deer, goats, and sheep)Early E. coli outbreaks associated with contaminated ground meatNow associated with farm workers not having adequate bathroom facilities60,000 yearly infections in the U.S. with a death rate of 1/1,000

Reduce Diffusion of Disease

Cover your mouth when you cough or sneezeWash your hands regularly when ill

Human Habits for Health

Eat rightGet exerciseAvoid smokingGet enough sleepTake time to relax

The Bubonic PlagueThe Plague is a contagious disease caused by

the agent bacillus, a rod-shaped bacteria, that resides in the intestines of fleas.

The Plague’s Hosts

The primary hosts of the plague are fleas, but rodents, cats, dogs, and humanscan also become intermediary hosts.

The PlagueThe 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.

Symptoms of the PlagueHeadachesWeaknessChills

PustulesSwollen lymph nodesBleeding under skin

Plague Pandemics

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

The First Pandemic

Resulted in people flocking to the ChurchChurch gained power

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

The Third PandemicBegan in 1855Truly globalPlague bacillus identified in 1894Discovered in 1898 that fleas transmitted diseaseCure found in the 1930sReservoirs established in the Americas

World Distribution of Plague