history of epidemics
DESCRIPTION
Influenza Lipid bilayer has H spikes (hemagglutinin) and N spikes (neuraminidase), i.e. H5N1 Influenza, 80 nm diameterTRANSCRIPT
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. 2003.• Human-to-human transmission????
– Not yet detected.
http://www.who.int/influenza/human_animal_interface/EN_GIP_20140124CumulativeNumberH5N1cases.pdf?ua=1
Origins of Influenza
• 412 BC – Hippocrates records epidemic• 1580 – 1st recorded pandemic• 31 major pandemics since then
(suspected)• 1933 – British scientists isolate virus
http://www.stanford.edu/group/virus/1999/rahul23/timeline.htmlhttp://www.althealth.co.uk/services/info/misc/influenza4.php
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
http://www.macalester.edu/~cuffel/molecularplague.htm
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.)
http://dermatology.about.com/cs/smallpox/a/smallpoxhx.htm
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
Microbiology’s “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
Koch’s 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 anthracisMycobacterium tuberculosisVibrio choleraeStaphylococcus aureus
• Never done for Treponema pallidum
Koch’s Postulates in Modern Microbiology
• Still the standard procedure
• Used in 2004 for SARS
• Never done for Treponema pallidum