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Pandemics Throughout History

Pandemics Throughout History. A pandemic is defined as an unusually high outbreak of a new infectious disease that is spreading through the human population across a large region “pan” – all, “demos” – people.

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Pandemics Throughout History

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  1. Pandemics Throughout History

  2. A pandemic is defined as an unusually high outbreak of a new infectious disease that is spreading through the human population across a large region • “pan” – all, “demos” – people

  3. According to the World Health Organization (WHO), a pandemic can start when three conditions have been met: • emergence of a disease new to a population; • agents infect humans, causing serious illness; and • agents spread easily and sustainably among humans.

  4. Throughout human history there have been numerous pandemics, including the bubonic plague, smallpox, cholera, the Spanish influenza, and more recently HIV • In 2009, we were faced with another pandemic - with the novel strain of influenza A, H1N1 – otherwise known as swine flu

  5. The Bubonic Plague (1347-1352) • Also known as the “Black Death” • Caused by a bacteria (Yersinia pestis) carried by rats and spread by fleas • Infectious agent: Yersinia pestis • Reservoir: rats • Vector: fleas • Kills within 3-7 days if untreated • Killed tens of millions across Europe (between ¼ and ½ of the total population)

  6. Cholera Pandemic (1817-1823) • A water-borne bacteria, Vibrio cholerae causes severe diarrhea leading to dehydration and death • The first pandemic was characterized by the unprecedented spread of the bacteria throughout Asia, starting at the Lower Ganges River in India • Total estimated deaths: 30 000

  7. SmallPox (18th Century onwards…) In total, smallpox killed more than 300-500 million people around the world in the 20th century A very contagious disease caused by viruses, Variola major (killed 30 to 30 percent of its victims) and Variola minor (killed about 1 percent) Smallpox localizes in the small blood vessels in the skin, mouth and throat – causes a rash and then, fluid-filled blisters Can leaves scars, blindness, limb deformities in survivors

  8. Smallpox….continued • Smallpox has been around since 10,000 BC • Killed an estimated 400,000 Europeans in the 18th century • Smallpox devastated Aboriginal populations in North and South America (90 to 95 percent died) • As recently as 1967, around 15 million people contracted the disease and 2 million of those died • The disease is the only human infectious disease that has been eradicated (1979 – due to vaccination campaigns)

  9. Spanish Influenza (1918-1920) • A very virulent influenza A subtype H1N1 strain • Approximately 1/3 of the world’s population became infected, and anywhere from 50 to 100 million people died worldwide (10-20% of those infected)

  10. WW I killed 15 mill., WWII 12 mill., Spanish flu 50 mill.

  11. HIV (human immunodeficiency virus) is a retrovirus (RNA virus that produces DNA ,which is incorporated into the host DNA) • HIV can cause AIDS (acquired immunodeficiency syndrome) • It is thought to have originated in sub-Saharan Africa • HIV is passed through sexual relations, blood or blood products, and mother-to-child transmission

  12. HIV and AIDS • 2.6 million new people were infected with HIV in 2009 • 1.8 million people died in 2009 • The number of new infections and AIDS-related deaths are declining steadily due to antiretroviral therapy

  13. People living with HIV (2008) • In 1990, 8 million people were living with HIV, in 2009 it was 33 million (the population of Canada)

  14. The “swine flu”: H1N1 (April 2009 - ?) • Caused by a strain of influenza A, H1N1 • Originated as a mixture of swine, avian, and human influenzas • The genetic change that allows a virus to “jump species” is called antigenic shift

  15. Influenza is mainly a disease of water fowl H1-16\N1-9

  16. H3N8 H2N2 H2N2 H1N1 PandemicH1N1 H3N2 2015 2010 1915 1925 1955 1965 1975 1985 1995 2005 1895 1905 H1N1 H9* Recorded new avian influenzas 1999 H5 1997 2003 H7 1980 1996 2002 1955 1965 1975 1985 1995 2005 Pandemics of influenza Recorded human pandemic influenza(early sub-types inferred) 2009 Pandemic influenza H1N1 1889 Russian influenza H2N2 1968 Hong Kong influenza H3N2 1918 Spanish influenza H1N1 1900 Old Hong Kong influenza H3N8 1957 Asian influenza H2N2 Animated slide: Press space bar Reproduced and adapted (2009) with permission of Dr Masato Tashiro, Director, Center for Influenza Virus Research, National Institute of Infectious Diseases (NIID), Japan.

  17. Antigenic Drift Mutation in haemagglutinin RNA Haemagglutinin Neuraminidase Antibodies bind to haemagglutinin; inhibit infection Antibodies can no longer bind to haemagglutinin; infection and disease results

  18. Antigenic Shift Human and avian flu viruses infect same host cell (eg. swine); exchange of segments occurs New subtype of influenza with potential to cause a pandemic may be produced

  19. PB2 PB1 PB2 PA PB1 HA PA NP HA NA NP MP NA NS MP NS PB2 PB1 PA HA NP NA MP NS Genetic origins of the pandemic (H1N1) 2009 virus: viral reassortment N. American H1N1 (swine/avian/human) Eurasian swine H1N1 Pandemic (H1N1) 2009, combining swine, avian and human viral components Classical swine, N. American lineage Avian, N. American lineage Human seasonal H3N2 Eurasian swine lineage

  20. Clinicalsymptoms Asymptomatic Seasonal influenza compared to pandemic — proportions of types of cases Deaths Requiring hospitalisation Clinicalsymptoms Deaths Requiring hospitalisation Asymptomatic Seasonal influenza Pandemic

  21. What we know so far ABOUT 2009 H1N1 • Infection rate for probable and confirmed cases highest in 5−24 year age group. • Hospitalisation rate highest in 0−4 year age group, followed by 5−24 year age group. • Pregnant women seem particularly at risk • Most deaths in 25−64 year age group in people with chronic underlying disease. • Adults, especially 60 years and old, may have some degree of preexisting protection • There are some predictions that up to 1/3 of the population could become infected…

  22. Swine Reality Video

  23. What can we do to prepare ourselves for a pandemic?

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