Lecture 26: Spanish Flu, Bird Flu and Swine Flu
Lecture 26: Spanish Flu, Bird Flu and Swine Flu
The last 4 major Influenza pandemics
Date
Deaths
Subtype involved
Asiatic Flu
1889–1890
1 million
H2N2 ?
Spanish Flu
1918–1920
40 to 100 million
H1N1
Asian Flu
1957–1958
1 to 1.5 million
H2N2
Hong Kong Flu
1968–1969
0.75 to 1 million
H3N2
Name of pandemic
What causes antigen shift? Why do influenza pandemics have Asian names? What’s with ‘Spanish’ flu then?
Reassortment A mixing of the genetic material of two similar viruses that are infecting the same cell.
Human influenza strains Low virulence to humans, highly infectious to humans Bird influenza strains High virulence to humans, low infectiousness to humans
Reassortment in a pig coinfected with both strains could lead to: High virulence to humans AND Highly infectious to humans
Avian Flu H5N1
Year
Deaths Cases
Mortality
2003
4
4
100%
2004
32
46
70%
2005
43
98
44%
2006
79
115
69%
2007
59
88
67%
2008
33
44
75%
2009
32
73
44%
(2010)
5
18
28%
Overall
287
486
59%
(WHO data as of 7/1/2009
Mortality of ‘normal’ seasonal flu ~ 0.2% Mortality of Spanish Flu ~2%
1918 Influenza pandemic aka Spanish flu 50-100 million dead (mortality)
20% of world infected (morbidity)
AIDS killed 25 million people in 25 years Spanish Flu killed 25 million people in 25 weeks
1918 Influenza pandemic aka Spanish flu 50-100 million dead (mortality)
20% of world infected (morbidity) Morbidity The state of being diseased.
Name of pandemic
Date
Morbidity Mortality
Deaths
Spanish Flu H1N1
1918–1920
High
Medium
40 to 100 million
Hong Kong Flu H3N2
1968–1969
High
Low
0.75 to 1 million
(2003-)
Very Low
High
486
2009-
High
(Bird flu H5N1) Swine Flu H1N1
Very Low
14,000 so far
Preventing Influenza Deaths •Antibiotics •Ventilators and steroid drugs •Prevent heart attack deaths •Antiviral drugs such as Tamiflu
Influenza age specific mortality rates
Influenza age specific mortality rates
Mortality rates Regular seasonal flu Spanish flu
0.2% 2%
The last 4 major Influenza pandemics
Date
Deaths
Subtype involved
Asiatic Flu
1889–1890
1 million
H2N2 ?
Spanish Flu
1918–1920
40 to 100 million
H1N1
Asian Flu
1957–1958
1 to 1.5 million
H2N2
Hong Kong Flu
1968–1969
0.75 to 1 million
H3N2
Name of pandemic
What causes antigen shift? Why do influenza pandemics have Asian names? What’s with ‘Spanish’ flu then?
Reassortment A mixing of the genetic material of two similar viruses that are infecting the same cell.
Human influenza strains Low virulence to humans, highly infectious to humans Bird influenza strains High virulence to humans, low infectiousness to humans
Reassortment in a pig coinfected with both strains could lead to: High virulence to humans AND Highly infectious to humans
Avian Flu H5N1
Year
Deaths Cases
Mortality
2003
4
4
100%
2004
32
46
70%
2005
43
98
44%
2006
79
115
69%
2007
59
88
67%
2008
33
44
75%
2009
32
73
44%
(2010)
5
18
28%
Overall
287
486
59%
(WHO data as of 7/1/2009
Mortality of ‘normal’ seasonal flu ~ 0.2% Mortality of Spanish Flu ~2%
1918 Influenza pandemic aka Spanish flu 50-100 million dead (mortality)
20% of world infected (morbidity)
AIDS killed 25 million people in 25 years Spanish Flu killed 25 million people in 25 weeks
1918 Influenza pandemic aka Spanish flu 50-100 million dead (mortality)
20% of world infected (morbidity) Morbidity The state of being diseased.
Name of pandemic
Date
Morbidity Mortality
Deaths
Spanish Flu H1N1
1918–1920
High
Medium
40 to 100 million
Hong Kong Flu H3N2
1968–1969
High
Low
0.75 to 1 million
(2003-)
Very Low
High
486
2009-
High
(Bird flu H5N1) Swine Flu H1N1
Very Low
14,000 so far
Preventing Influenza Deaths •Antibiotics •Ventilators and steroid drugs •Prevent heart attack deaths •Antiviral drugs such as Tamiflu
Influenza age specific mortality rates
Influenza age specific mortality rates
Mortality rates Regular seasonal flu Spanish flu
0.2% 2%
