In seeking to understand the remarkably deadly 1918 flu pandemic
which killed at least 20 million people around the planet
scientists have focused on the influenza virus, combing its
genes for clues to its malevolence. But demographer Andrew
Noymer of the University of California at Berkeley thinks people
are overlooking a second culprit: Mycobacterium tuberculosis,
the tuberculosis bacterium. Noymer reached his iconoclastic
conclusion after poring over acres of data on 20th-century death
rates in the United States. One statistic stood out. The rate of
deaths from TB plunged from 157 per 100,000 in 1918 to 103 per
100,000 in 1921, right after the flu pandemic. He found no
similar decrease in mortality from other chronic ailments such
as cancer. That pattern implies that many of those who died from
the flu were already infected by TB. And he notes that M.
tuberculosis carves out cavities in the lung. Those cavities
would have been perfect breeding grounds for pneumonia, which
finished off most flu victims in 1