The 1918 Spanish flu pandemic killed some 500,000 Americans and 20 million to 50 million people worldwide. Photo shows a crowded emergency hospital at Fort Riley, Kan.
Will some teenage Thai cockfighter who swaps spit with his rooster cause the next great flu pandemic?
Recently the Thailand Department of Disease Control reported on the flu death of an 18-year-old male. They said that the boy had ''had very close contact to . . . fighting cocks by carrying and helping to clear up the mucous secretion from the throat of the cock during the fighting game by using his mouth.''
That is, the young man -- in a move not uncommon in cockfighting circles -- had cleared the cock's airway by sucking his rooster's beak and then swallowing the spit and mucus. Is this the pathway that allows avaian or "bird flu" to jump to humans? The NY Times reports:
Between January and the end of October, 32 people have died from avian influenza in Vietnam and Thailand. Tens of millions of chickens have succumbed. Millions of others have been slaughtered. More nations have admitted to outbreaks among birds in more provinces than would have been conceivable even 18 months ago. All of this, Fukuda says, ''certainly increases the possibility'' of a much larger outbreak of avian flu among people...
Influenza viruses are divided into three types: A, B or C, depending on the virus structure. Humans can be infected with all three, although C-class flus are uncommon and influenza B doesn't usually cause severe illness except among children.
Influenza A is the monster, in both animals and people, causing, by and large, the most virulent illness. Type A influenzas (unlike B's or C's) have multiple subtypes, identified with maddeningly cryptic names: H3N2, H1N1, H7N2. The ''H'' is for hemagglutinin, a spiky protein on the surface of the influenza molecule. In human flu viruses, the spikes of hemagglutinin connect, like sinister Legos, with matching receptors on the outside of healthy respiratory-system cells. The virus then melds with the healthy cell and begins replicating. Neuraminidase, the ''N'' in the flu name, another protein, uncouples the virus from its host, tearing the cell membrane and allowing the progeny to escape, killing the cell. Loosed, they start repeating the process deeper and deeper into the respiratory tract...
To cause a pandemic, an entirely new human influenza subtype must emerge, one that most people would never have been exposed to and would not have immunities to. This flu also must be able to be transmitted efficiently from person to person. In recent history, three main types of influenza A have circulated freely in humans. (Many more exist in birds.) Each of these strains caused a pandemic when they were introduced into the human race. The catastrophic 1918 Spanish flu pandemic was caused by H1N1. The 1957 Asian flu pandemic, which killed 70,000 in the United States, was brought about by H2N2. And the 1968 pandemic of Hong Kong flu introduced H3N2. That outbreak killed about 34,000 people in the United States.
Science doesn't quite understand how a nonhuman flu virus adapts and becomes a human flu, and why more, in fact, don't. But they do suspect that it is a process of gene swapping. If an avian flu infects a person who, coincidentally, suffers from a human flu, the two bugs might exchange genetic material. The resulting virus could be essentially avian, but possessing genetic components of the human flu that would allow it to be easily transmitted from person to person. This is how the Asian flu and the Hong Kong flu pandemics began.
The Flu Hunters [NY Times]
Flu Coverage [NY Times]
Bird Flu Is Back, Raising Fear of Spread Among Humans [NY Times]
Bird Flu Deaths in Thailand Raise New Fears [NY Times]
Thais Suspect Human Spread of Bird Flu [NY Times]
Weekly Flu Report [CDC]
Flu Activity-Reports & Surveillance [CDC]
Wednesday, November 10, 2004