cover image Biography of a Germ

Biography of a Germ

Arno Karlen. Pantheon Books, $22 (178pp) ISBN 978-0-375-40199-2

The germ is Borrelia burgdorferi, Bb for short, and causes Lyme disease in the people it infects: before it hits a human, Bb has to reside in three other animals--a mouse, a tick and a deer, in that order. This odd property, and the germ's wide distribution, means that Bb has been affected by changes in human land use--factories, clear-cuts, the growth of the suburbs and the environmental movement all had to happen for Lyme to become something Americans think about. And think about it we do: Bb is now so interesting that in 1997 scientists mapped its genome. All these facets make Bb the ideal candidate for what Karlen (Man and Microbes, etc.) claims is the first history of a pathogen written from that pathogen's perspective. Fascinating in their own right, Bb and its relatives also demonstrate larger patterns and questions in the study and history of microbes and molecular biology, of zoology and ecology, of medicine, public health policy and disease. In 22 brief chapters, Karlen lays out and answers some of those questions. He tells of Bb's sibling spirochetes, which cause syphilis and tropical diseases. He explains how ticks' adaptations let them parasitize ""a chipmunk or a human,"" ""a wren or a raccoon,"" and how Bb's adaptations let it jump between ticks and their hosts. Karlen has created a vigorous, compact account of Bb's life and times. And beyond the zoology and disease control, Karlen even offers a message: ""Pathogens... are just trying to survive, and sometimes they must do so at other creatures' expense."" The same could be said of humans."" (June)