History of Epidemics.

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Influenza Lipid bilayer has H spikes (hemagglutinin) and N spikes (neuraminidase), i.e. H5N1 Influenza, 80 nm diameter

Transcript of History of Epidemics.

History of Epidemics Influenza Lipid bilayer has H spikes
(hemagglutinin) and N spikes (neuraminidase), i.e. H5N1 Influenza, 80 nm diameter 1918 1919 Pandemic The Spanish Flu 20 50 million deaths worldwide
Infections developed into pneumonia U.S. soldiers brought it to the world during WWI Preceded by mild epidemic in spring/summer. H1 strain Other Epidemics 1957: 2M dead; H2 strain; Asian Flu
1968: 1M dead; H3 strain; Hong Kong Flu ~68 year cycles H5N1 Avian Flu [2013] 650 human cases confirmed by WHO.
386 deaths confirmed by WHO. 125/62 in Vietnam; 25/17 in Thailand; 195/163 in Indonesia; 45/30 in China; 47/33 in Cambodia; 173/63 in Egypt. Since Dec Human-to-human transmission???? Not yet detected. Origins of Influenza 412 BC Hippocrates records epidemic
1580 1st recorded pandemic 31 major pandemics since then (suspected) 1933 British scientists isolate virus Bubonic Plague Yersinia pestis
Carried by fleas (between rodents & humans) Respiratory transmission in later stages Bacteria reproduce in blood & lymph Very high mortality Pneumonic Plague Outbreak in Western China, Aug 09.
11 reported cases all fatal. Quarantine. Ziketan in Qinghai Province. Origins of the Plague 430 BC 1st epidemic recorded in Athens
Peloponnesian War Killed 300,000 1/3 of Greek population Several epidemics from 500s to 700s AD ranging from Mediterranean Europe to Central and Southern Asia Plague in Europe Returns to Europe in 1300s after 600 years with few signs Now known as the Black Death Up to 28M Europeans killed (~40% of population) Smaller epidemics over next 400 years Plague 1300s 1/3 of Asian population is killed
By late 1800s new epidemics in China, Africa and elsewhere 1894 epidemic in Hong Kong; bacterium (the etiological agent) is isolated 1994 Possible epidemics in India, Malawi, and Mozambique Confusing the Plague Historical records may not be accurately interpreted Can be confused with other diseases, such as typhoid fever Small Pox (Variola) Virus infects internal organs
Later stage can result in lesions on skin Some forms can have a mortality rate >20%; others have a low rate Respiratory transmission Origins of Smallpox Probably in Africa thousands of years ago
1350 BC 1st recorded epidemic in Egypt 5th Century reached Europe Many major epidemics in Europe until 1400s Building immunity in population Small Pox in the Western Hemisphere
Native Americans had little or no exposure to the virus Little immunity in the population Killed a large portion of Native Americans as Europeans colonized the West Unintentional and intentional! Vaccination ~1050 A.D. Buddhist nun in China practices variolation
Grinds up smallpox scabs into powder Blows the powder up nostrils of uninfected patient Mild disease results (~97%) Practiced in much of Asia by 1700s Vaccination in Europe 1790s Edward Jenner uses cow pox scabs to stimulate immunity Experiments with an 8 year old boy 1800 100,000 people are vaccinated 1967 WHO begins eradication effort 1972 last vaccinations in US general population 1977 last reported case in Somalia 1980 World declared free of smallpox Except for two labs (U.S. and U.S.S.R.) War & Infectious Disease
Treatment of soldiers Wounds, extreme physical conditions, trenches, chemical exposure, etc. Uprooted civilians Crowded refugee camps, reduced healthcare. Destruction of infrastructure Water & sewage treatment, food distribution, etc. E.g. cholera, typhus, malaria. Poverty & Infectious Disease
Little access to healthcare. Poor nutrition. Hazardous jobs. Proximity to toxic environments. Less education. E.g. HIV/AIDS, TB, malaria, cholera, and more. The Big Three HIV/AIDS TB Malaria Diarrheal diseases Pneumonia How Do We Know About Microorganisms? First Microscopes 17th Century Robert Hooke the cell theory
observed cork Antoni van Leeuwenhoek animalcules observed living samples Hooke van Leeuwenhoek (fig. 1.2) Biogenesis 1861 Louis Pasteur uses flasks with S-shaped neck
Boils the nutrient broth, air can get into flask, but nothing grows This is considered the definitive proof of Biogenesis! Fig. 1.3 Microbiologys Golden Age
1857 1914 Pasteur demonstrates that yeasts ferment sugars beer & wine Bacteria can cause food spoilage Pasteurization! Can Microbes Cause Disease?
Germ Theory of Disease says, YES! 1860s Joseph Lister uses phenol to disinfect surgical wounds 1860s US Civil War: lots of battlefield surgery led to gangrene, until bromine was introduced as disinfectant Also, better sanitation was needed to prevent cholera and dysentery Ignaz Semmelweis Kochs Postulates Method of proving that a particular microbe causes a disease Isolate an organism from the diseased tissue (from human patient) Grow them in pure culture Inject them into animal to cause the disease Re-isolate the bug/germ/microbe from the animal Fig. 14.3 Robert Koch, 1870s & 1880s Used his postulates to discover:
Bacillus anthracis Mycobacterium tuberculosis Vibrio cholerae Staphylococcus aureus Never done for Treponema pallidum Kochs Postulates in Modern Microbiology
Still the standard procedure Used in 2004 for SARS Never done for Treponema pallidum