EPIDEMIOLOGIC TRANSITION

What is epidemiology? Epidemiology,  branch of medical SCIENCE that studies the distribution of DISEASE in human populations and the factors determining that distribution, chiefly by the use of STATISTICS.

THE EPIDEMIOLOGIC TRANSITION The Epidemiologic transition is that process by which the pattern of mortality and disease is transformed from one of high mortality among infants and children and episodic famine and epidemic affecting all age groups to one of degenerative and man- made diseases (such as those attributed to smoking) affecting principally the elderly.

Disease Vocab Epidemic – disease prevails over a large area Endemic – disease prevails over a small area Pandemic – disease is global in scope. Vectored Disease – Disease transmitted by an intermediary (IE. mosquito) Non-Vectored Disease – Disease transmitted by direct contact between host and victim (IE. The Flu) Disease Vocab

The theory of Abdel Omran In 1971, Abdel Omran published a seminal paper: To characterize population change.   The epidemiologic transition is a stage of development characterized by a shift in population growth, life expectancy and disease patterns.  

Stages of Epidemiologic Transition

Stage I: Epidemics/Pandemics Infectious and parasite diseases were principle causes of death along with accidents and attacks by animals and other humans. Thomas Malthus called these caused of death “natural checks” Most violent Stage I epidemic was the Black Plague (bubonic plague or black death) probably transferred to humans by fleas from infected rats

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Stage II: Receding Pandemics Improved sanitation, nutrition, and medicine during the Industrial Revolution reduced the spread of infectious diseases. Isolated infectious diseases Death rates did not improve immediately and universally during the early years of the Industrial Revolution. Poor people who crowded into Industrial Cities had high death rates due to cholera, an acute case of diarrhea and vomiting that can kill within hours if left untreated. Cholera, TB, Malaria, Meningitis, AIDS

Tuberculosis Death Rates, 2000 The tuberculosis death rate is a good indicator of a country’s ability to invest in health care. TB is still one of the world’s largest infectious-disease killers.

HIV/AIDS prevalence rates, 2002 The highest HIV infection rates are in sub-Saharan Africa. India and China have large numbers of cases, but lower infection rates at present.

Cholera in London, 1854 By mapping the distribution of cholera cases and water pumps in Soho, London, Dr. John Snow identified the source of the waterborne epidemic.

Stage III: Degenerative Diseases/Human created? Associated with the chronic diseases of aging decrease in deaths from infectious diseases and an increase in chronic disorders associated with aging Heart disease and cancer Sub-Saharan Africa and South Asia have low incidences of cancer primarily because of low life expectancy.

Stage IV: Delayed Degenerative Life expectancy of older people is extended through medical advances. Cancer medicines, bypass surgery, better diet, reduced use of tobacco, and alcohol However, consumption of non-nutritious food and sedentary behavior have resulted in an increase in obesity in this stage. Longer life expectancy Stage IV: Delayed Degenerative

Heart Attack Grill QUESTIONS: What kind of impact does a nation’s eating habits have on overall population? What kind of impact does geography and culture have on what people eat? Nationally? Internationally? https://www.youtube.com/watch?v=hqf_SIQ3JAk

Possible – Stage 5 Some medical analysts argue that the world is moving into stage 5 with a reemergence of infectious and parasitic diseases Thought to have been eradicated or controlled, some infectious diseases have emerged

3 Possible Reasons for Stage 5 Evolution – new strains due to drug resistance (malaria) Poverty- more infections due to unsanitary conditions, expensive (TB/ “consumption”) Increased connections – spread through relocation diffusion (H1N1/swine, severe acute respiratory syndrome (SARS) – entered U.S. through NY, CA, and FL.

The World’s deadliest infectious diseases

Bio-Terrorism Some fear that terrorists may also be responsible for spreading infectious diseases.

What impacts the ability of diseases to diffuse? Population density and urbanization—high density equates to high rate of diffusion. Over 50% of the global population live sin urban areas. With more people living in dense conditions, there is more frequent contact between more individuals, allowing disease transmission to easily occur (Contagious Diffusion) Migration and global travel—Relocation diffusion Environmental degradation—especially common in vector borne diseases (Zika) All of the above factors will influence the rate of diffusion also known as R-Nought Avg. number of people who will contract the disease from one contagious person. Does not include vaccinated people. Any R Nought greater than 1 could potentially lead to an epidemic 1918 Swine Flu (R Nought of 2.6—killed 50 million people