Download - 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
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.
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
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)
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
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
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)
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)
WW I killed 15 mill., WWII 12 mill., Spanish flu 50 mill.
HIV (human immunodeficiency
virus) is a retrovirus (RNA virus that produces DNA ,which is incorporated into the host DNA)
o 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
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
PEOPLE LIVING WITH HIV (2008)
In 1990, 8 million people were living with HIV, in 2009 it was 33 million (the population of Canada)
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
Influenza is mainly a disease of water fowl
H1-16\N1-9
PANDEMICS OF INFLUENZA
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H7
H5
H9*
1980
1997
Recorded new avian influenzas
1996 2002
1999
2003
1955 1965 1975 1985 1995 2005
H1N1
H2N2
1889RussianinfluenzaH2N2
H2N2
1957AsianinfluenzaH2N2
H3N2
1968Hong KonginfluenzaH3N2
H3N8
1900Old Hong Kong influenzaH3N8
1918SpanishinfluenzaH1N1
1915 1925 1955 1965 1975 1985 1995 20051895 1905 2010 2015
2009PandemicinfluenzaH1N1
Recorded human pandemic influenza(early sub-types inferred)
Reproduced and adapted (2009) with permission of Dr Masato Tashiro, Director, Center for Influenza Virus Research, National Institute of Infectious Diseases (NIID), Japan. Animated slide: Press space bar
H1N1Pandemic
H1N1
RNA
Haemagglutinin
Neuraminidase
Antibodies bind to haemagglutinin; inhibit infection
Antigenic Drift
Mutation in haemagglutinin
Antibodies can no longer bind to haemagglutinin; infection and disease results
Antigenic ShiftAntigenic 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
GENETIC ORIGINS OF THE PANDEMIC (H1N1) 2009 VIRUS: VIRAL REASSORTMENT
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PB2PB1PAHANPNAMPNS
PB2PB1PAHANPNAMPNS
PB2PB1PAHANPNAMPNS
Classical swine, N. American lineageAvian, N. American lineageHuman seasonal H3N2Eurasian swine lineage
Eurasian swine H1N1
N. American H1N1(swine/avian/human)
Pandemic (H1N1) 2009, combining swine, avian and human viral components
SEASONAL INFLUENZA COMPARED TO PANDEMIC — PROPORTIONS OF TYPES OF CASES
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Asymptomatic
Clinicalsymptoms
Deaths
Requiring hospitalisation
Seasonal influenza Pandemic
Asymptomatic
ClinicalsymptomsDeaths
Requiring hospitalisation
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…
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Swine Reality Video
What can we do to prepare ourselves for a pandemic?