Plagues Exam 1

A harmful deviation from the normal structural or functional state of an organism

Infectious disease moves from person to person to person - it's communicable (or animal to animal or plant to plant). non-infectious disease does not move from host to host. Transmission is a formal term and understanding how a disease is transmitted is crucial to its management

Diseases and pathogens are similar, but not the same. Pathogens cause disease in the appropriate environment. ex. pneumonia is a general description for severe lung congestion, a disease and may be caused by a number of bacteria or viruses (pathogens)

Disease is hte result of several factors coming together in a dynamic system. Can be simplified to 3 basic components: host, pathogen and environment. With one component missing, no idsease. Can also be used to manage disease

People died very young. For example, in the 17th century there were gravestones of people 17 and 20 years old. in 6000 BC in Turkey the mean (50% dead) life expectancy was 20-25. This was the same life expectancy for london in 1728 and in 1830 it increased a bit, but not by much. in 1861 the mean life expectancy was early 50's (70% still living at age 20). In the U.S. in 1985 the mean life expectancy was much higher and at age 20 almost 100% of people were still living

Tuberculosis, pneumonia, diarrhea 30%. Diptheria, bronchitis, 5%. Heart disease, cancer, stroke, 16%. Injuries 5%.

Heart Disease, cancer, stroke 62% (increased from 16% in 1900). Injuries 4%. TB, flu, pneumonia, diarrhea 4%. Diptheria, bronchitis not significant

Diptheria, pertissis, measles and polio rates all bottomed out by 2000. Diptheria was very high in 1900 and then dropped quickly to nothing by 2000.

Dropped drastically with a peak around 1920. Why the differences in mortality?: vaccines, antibiotics, antiseptics, drugs, clean water (sewage treatment), "cleaner" food - pasteurization, refrigeration. research and education, pesticides

1962: Australian Nobel laureate said that mid 20th century had seen "the virtual elimination of the infectious disease as a significant factor in social life
1967: U.S. Surgeon General announced "time to close the books on infectious disease and shift all national efforts to chronic diseases
1990s: Resurgence of infectious diseases

Emerging diseases: new diseases (like AIDs emergence)
Re-emerging diseases: Diseases that were once a problem, receded, but are making a comeback (like tuberculosis in Russia)

Although mortality stayed relatively stable, morbidity spiked after the collapse of the Soviet Union in the 90s because access to healthcare was more difficult and jails are overloaded. also a resistant strain of tuberculosis was selected for. Tuberculosis was a re-emerging disease

1. Living things evolve and develop offensive mechanisms (pathogens have virulence - relative ability of a microorganism to cause disease)
2. Microbes evolve quickly (in a matter of hours) and reproduce rapidly (can change with each generation)
3. They adapt to antibiotics. For example: tuberculosis bacteria have become resistant to antibiotics

In much of the world infectious disease never decreased. in 2001 7/10 leading causes of death in poor countries were infectious diseases, whereas in rich countries only 1/10 (tuberculosis)