Transcript Pandemics 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, fluidfilled 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
mill.
I killed 15 mill., WWII 12 mill., Spanish flu 50
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 (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
SEASONAL INFLUENZA COMPARED TO PANDEMIC —
PROPORTIONS OF TYPES OF CASES
Deaths
Requiring
hospitalisation
Clinical
symptoms
Deaths Requiring
hospitalisation
Clinical
symptoms
Asymptomatic
Seasonal influenza
Asymptomatic
Pandemic
22
EVERYONE
IS WORRYING
ABOUT
INFLUENZA
(KIDS,
PARENTS,
TEACHERS...)