Today I will continue what I started with yesterday's post, using quotes from this book to answer questions about the influenza pandemic of 1918-1919. From this information, I think we can get more knowledge about the predicted upcoming bird flu pandemic. (These page numbers came from the hardbound copy of the book.)
How do scientists name the various strains of influenza virus?
p. 109 The chief antigens of the influenza virus are the hemagglutinin and neuraminidase protruding from its surface...those two parts mutate the fastest.
p. 111 Hemagglutinin occurs in 15 known shapes, neuraminidase in nine, and they occur in different combinations with subtypes. Virologists use these antigens to identify what particular virus they are discussing..."H1N1", for example, is the name given the 1918 virus...An "H3N2" virus is circulating among people today. (written in 2004). (The Reuters story in my post "Bird Flu Pandemic" lists today's strain as "H5N1".)
p. 115 The 1957 pandemic, "Asian Flu", was caused by H2N2. The 1968 pandemic, "Hong Kong Flu", H3N2, made many sick, but killed few.
The influenza virus is constantly mutating. What will be the results of that?
p. 110. "Antigen shift", these are the mutations that occur which change the virus to different forms.
p. 111 When antigen shift occurs, the immune system cannot recognize the antigen at all. Few people in the world will have antibodies that can protect them against this new virus, so the virus can spread through a population at an explosive rate...
Have there ever been influenza pandemics before or after the one in 1918-1919?
p. 113-114 There is no dispute, though, that other pandemics in the past were influenza. In 1688...influenza struck England, Ireland, and Virginia...as a plague...Five years later, influenza spread again across Europe...At least three and possibly six pandemics struck Europe in the eighteenth century, and at least four struck in the nineteenth century. In 1847 and 1848 in London, more people died from influenza than died of cholera during the great cholera epidemic of 1832. And in 1889 and 1890 a great worldwide ...pandemic struck again. In the twentieth century, three pandemics struck. Each was caused by an antigen shift...
How many people got sick in 1918-1919? How many people died?
p. 232 Generally in the Western world, the virus demonstrated extreme virulence or led to pneumonia in from 10-20 percent of all cases. In the United States, this translated into two or three million cases. In other parts of world, chiefly in isolated areas where people had rarely been exposed to influenza viruses...the virus demonstrated extreme virulence in far more than 20 percent of cases. These numbers most likely translate into several million severe cases around the world in a world with a population less than one-third that of today.
p. 363-364 In Chiapas, Mexico, 10% of the entire population died. In Guam, 5% of entire native population died. In Brazil, Rio de Janeiro suffered an attack rate of 33%. In Buenos Aires, Argentina, the virus attacked nearly 55% of the population. In the Fiji Islands, 14% of the population would die in the sixteen days between Nov. 25 and Dec. 10, 1918. In the very few isolated locations around the world, where it was possible to impose a rigid quarantine, they were able to escape the disease entirely. American Samoa had not one single death from influenza. In Western Samoa, 22% of the population died. In the Indian subcontinent, it is likely that close to 20 million died.
(I will post more quotes from this book on March 22.)
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