Transcript History of Influenza

History of Influenza
Etymology of “Influenza”
• Greek “influentia”
– “Flow of liquid” or “influence”
– Used to express belief in
the impact of the stars on
appearance of epidemics
Oxford-English Dictionary.
Online Etymology Dictionary.
www.fluvirustoday.info
Etymology of “Influenza”
• Adopted by England as common name “influenza”
– After a 1743 flu outbreak which started in Italy
and spread throughout Europe
Oxford-English Dictionary.
Online Etymology Dictionary.
www.fluvirustoday.info
Hippocrates’s “Epidemic”
• “Epidemios” – residing in a place
• 5th century BC
• Cough of Perinthus
– Cough, sore throat, muscle aches,
voice problems, difficulty breathing
• Influenza?
Martin P & Martin-Granel E. Emerg Infect Dis. 2006;12.
http://www.cdc.gov/ncidod/EID/vol12no06/05-1263.htm
Richards DW. J Am Med Assoc. 1968;204:1049-56.
Epidemic vs. Pandemic
• Epidemic
– Sudden onset of infection
– Large percentage of people
– Disappears in approximately
3 months
• Pandemic
– Appear suddenly in
–
–
an isolated area
Spread is worldwide
and infects millions
Large number of deaths
Potter CW. J Appl Microbiol. 2001;91:572–9.
Epidemic Rates Over 7-Year Periods
Influenza cases
Deaths from influenza
Winter deaths in non-flu year
8
Thousands x 103
7
6
5
4
3
2
1
0
Year 1
Virus Serotype
2
A
3
A
4
B
5
6
C
7
D
E
Adapted from Potter CW. J Appl Microbiol. 2001;91:572–9.
1580 Influenza Pandemic
• First record of influenza pandemic
– Classified as pandemic by physicians and historians
• Origins in Russia and crossed several major continents
–
–
–
–
Africa
Asia
Rome: Over 8,000 deaths
Spain: Several cities were depopulated
Potter CW. J Appl Microbiol. 2001;91:572–9.
1830-1833 Influenza Pandemic
• Widespread
• Infected ¼ of those exposed
• Began in China, to the Philippines, India, Russia,
Deaths (Millions)
and then Europe
2
1.5
1
0.5
1700
1800
1900
2000
Year
Adapted from Potter CW. J Appl Microbiol. 2001;91:572–9.
Spanish Flu: Severity
• “Greatest medical holocaust in history” (Waring, 1971)
• “Deaths in the hospital exceeded 25% per night in the peak”
(Starr, 1976)
Potter CW. J Appl Microbiol. 2001;91:572–9.
Spanish Flu: The Spread
• First outbreaks in 1918
– Detroit
– South Carolina
– San Quentin Prison
– Kansas
• Infection spread seen normal in spring
– American Expeditionary Force to British Expeditionary Force
– War in Europe
• Fall of 1918: more virulent form emerged
– 10-fold increase in deaths
• Estimated to have infected 50% of world’s population
• Total mortality: 40-50 million from 1918-1920
Potter CW. J Appl Microbiol. 2001;91:572–9.
Spanish Flu: Second Wave
• Increase in virulence between first and second wave
of Spanish Flu
– Possible rapid mutation of proteins on virus surface
– Possible mutation of viral RNA
– Novel subtype with no previous immunity in humans
under the age of 65
– Increased virulence correlated with ability to infect swine
• Later became known as the “swine flu”
Taubenberger JK. Proc Am Philos Soc. 2006;150:86-112.
Spanish Flu: Outbreak Map
Outbreak / Focal Point
First Wave (1918)
Second Wave (1920)
Adapted from Potter CW. J Appl Microbiol. 2001;91:572–9.
Asian Flu: Severity and Spread
•
•
•
•
•
Started in Yunnan Province, China
Disease then spread worldwide
New virus subtype
1957-1958; 40-50% of population infected
Total mortality: 1 in 4,000
Potter CW. J Appl Microbiol. 2001;91:572–9.
Asian Flu: Outbreak Map
Adapted from Potter CW. J Appl Microbiol. 2001;91:572–9.
2009 Flu Pandemic
• Not true “swine flu”
• Did not transmit from pigs
• Separate H1N1 strains common to humans, pigs, and birds
Zampaglione M. WHO. April 2009.
“Swine” H1N1 Influenza Virus
• United States: April 15, 2009 to July 24, 2009
– 43,771 confirmed and probable cases of novel Influenza A
Hospitalizations/100,000
in Age Group
–
–
(H1N1) infection
5,011 people were hospitalized
302 deaths
5
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0
0-4
5-24
25-49
50-64
Age Group in 2009
(Years)
≥ 65
Adapted from Novel H1N1 Flu: Facts and Figures. CDC. 2009.
“Swine” H1N1 Influenza Virus
• 2009 flu has a target infection age similar to Spanish Flu
30
Rate/100,000
in Age Group
25
20
15
10
5
0
0-4
5-24
25-49
50-64
≥ 65
Age Group in 2009
(Years)
Adapted from Novel H1N1 Flu: Facts and Figures. CDC. 2009.