February, 2005:
Although any new pandemic would be costly and dangerous, there are good reasons to think that avian flu would be unlikely to morph into a strain that is both virulent and highly transmissible among humans. As Ewald has pointed out, the 1918 flu may have developed its unique virulence, and its unique focus on young adults, precisely because of the terrible conditions in wartime Europe. The disease first appeared as a relatively mild outbreak in the United States in the spring of 1918. A far deadlier form incubated among soldiers on the Western Front. It stalked the trenches, the hospitals stacked with wounded, sick, and dying soldiers, the trucks that carted sick and wounded from one crowded hospital to another, the trains on which the immobilized sick lay face-to-face with the helpless wounded, and the boats that returned ill soldiers to the United States.
Only comparable conditions, Ewald says, would allow the development of a highly virulent and transmissible human flu. As the conditions that created the 1918 flu abated, so did the virulence of the disease and its specificity for healthy people in the prime of life. But it did not disappear. For decades after 1918, H1N1 wandered around the planet, a commonplace flu, no more virulent than any ordinary strain, a killer of the very old and the very young. It spread the way human flu strains always do—coughs and sneezes. Precisely because people have to be healthy enough to walk around and cough into other people’s faces, ordinary human flu strains must be relatively mild to spread. Lethal flu requires the sort of conditions found in the animal markets of Guangdong or the trenches of World War I.
No comments:
Post a Comment