Chapter 2 Key Issue 4

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epidemiologic transition


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epidemiologic transition

the branch of medical science conerned with the incidence, distribution, and control of diseases that are prevalent among a population at a special time and are produced by some special causes not generally present in the affected locality

Stage 1: Pestilence and Famine

-high CDR -Malthus calls these deaths "natural checks"

What were the main causes of human deaths in stage 1?

infectious diseases, parasitc diseases, and accidents and attacks from animals and other humans

What was history's most violent stage 1 epidemic?

the Black Plague

How many people died from the Black Plague?

25 million Europeans and 13 million Chinese

Stage 2: Receding Pandemics

rapidly declining CDR

What reduced the spread of infectious diseases?

-improved sanitation, nutrition, and medicine

What disease caused an epidemic during the Industrial Revolution?


What eradicated cholera?

the construction of water and sewer systems

In what areas did cholera persist and why?

developing regions (sub-Saharan Africa, South Asia, Southeast Asia, Hispaniola etc.); people lacked access to clean drinking water

What system helped to explain and battle stage 2 pandemics?

Geographic Information System (GIS)

Why were the poor more likely to be affected by cholera?

they were more likely to use contaminated water

Stage 3: Degenerative Diseases

moderately declining CDR

How is stage 3 characterized?

a decrease in deaths from infectious disases and an increase in chronic disorders associated with aging (cardiovascular diseases, cancer, etc.)

Why do sub-Saharan Africa and South Asia have the lowest incidence of cancer?

they have a low life expectancy

Stage 4: Delayed Degernative Diseases

low but increasing CDR

How is stage 4 characterized?

the major degenerative causes of death linger, but the life expectancy of older people is extended through medical advances, as well as better diets and excerise; bad diets result in obesity

Possible Stage 5: Infectious Diseases

a reemergence of infectious and parasitic diseases, resulting in a high CDR

What are the 3 reasons for stage 5?

evolution, poverty, and increased connections

Reason: Evolution

-infectious diseases are evolving and adapting to drugs and insecticides -antibiotics and genetic engineering add to the emergence of new strains of viruses and bacteria

How was malaria first eradicated? Why is it back?

DDT was sprayed in areas infested with mosquitos; the evolution of DDT-resistant mosquitoes

Reason: Poverty

-poorer areas have unsanitary conditions -people can't afford drugs for treatment

Why is tuberculosis still prevalent in poor areas?

patients are too poor to continue with the treatment, and stop taking the drugs

Reason: Increased Connections

-new pandemics are emerging because of relocation diffusion -motor vehicles, airplanes, etc. allow people to travel around much faster, able to spread a disease quicker

What are some of the most lethal pandemics?


Why did the number of cases of AIDS rapidly drop?

the expansion diffusion of medicines like AZT

infant mortality rate (IMR)

the annual number of deaths of infants under one year of age, compared with the total live births

What do low IMRs show about a country?

a good healthcare system; well-trained doctors and nurses, modern hospitals, and large supplies of medicine

What is the IMR in developed countries?


What is the IMR in sub-Saharan Africa?


life expectancy

the average number of years a newborn infant can expect to live at current mortality levels

Where is life expectancy high? What is it?

wealthy countries in Europe; 80

Where is life expectancy low? What is it?

poor countries of sub-Saharan Africa; 60

What do developed countries offer to people who are unable to work?

public assistance and healthcare

How much do government programs pay for healthcare costs? Individuals? (in developed countries)

more than 70%; less than 30% EXCEPTION: the US (individuals pay over 55%, similar to developing countries)

What are things that do NOT indicate overpopulation?

density, size, clustering in of a population

What is overpopultion indicated by?

the relationship between population and a region's level of resources

What is happening in overpopulated sub-Saharan Africa?

-inability of the land to sustain life -land declines in quality, causing more effort to be needed to yield the same amount of crops (extending the working day) -women have more children for help with work