Jointed threads: Joseph Leidy was the first to describe symbiotic bacteria growing together in long strings in animal intestines. Microbiological analyses now link the bacteria with anthrax.(NATURALIST AT LARGE)

Publication: Natural History

Publication Date: 01-JUN-05

Bookmark this article Print this article Link to this article Email this article Digg It! Add to del.icio.us RSS

COPYRIGHT 2005 Natural History Magazine, Inc.

Anthrax, once upon a time, was a marginal disease in people, afflicting sheepshearers and few others. Most people who contracted it at all got the cutaneous form of the disease, which forms black scabs on the skin that look like anthracite coal (hence the name "anthrax"). But in autumn 2001, around the time of the terrorist attacks on New York and Washington, deadly anthrax spores began to be spread in letters mailed to news organizations and prominent government officials. Several people inhaled the spores and died from the much more deadly pulmonary form of the disease. Fear of the anthrax contagion was rampant. The very idea that small quantities of white powder in envelopes could be anthrax spores has changed Post office practices to such a degree that they have adversely affected many citizens' daily routines, including my own.

Anthrax spores became infamous as a potential weapon during the Second World War, when the British test-fired anthrax bombs on the Scottish island of Gruinard. The bacterium's infectious spores spread across the island's 520 acres and left Gruinard uninhabitable for nearly fifty years. Not until the late 1980s was the island decontaminated. The cleanup required four years of effort by a large crew; wielding almost 300 tons of formaldehyde--a sobering testament to the durability, both temporal and chemical, of anthrax spores.

What is still unknown, even after the island's cleanup, is the bacterium's ecology. Is anthrax just a kind of bacterial sit-and-wait predator, which bides its time until a sheepshearer cuts himself or a letter handler inhales a cloud of spore-laden dust? The anthrax bacterium is readily grown in laboratory culture. But where is it in nature?

Our eclectic reading habits have helped my students and me disentangle one strand of the anthrax story. We recently discovered that a common laboratory bacterium, identical in all but the most trifling ways with the organism that causes anthrax, lives deep inside the intestines of many healthy animals. But the scientific story of anthrax does not begin with our work, or with the terrorist attacks of 2001, or even with the episode on Gruinard. It begins in the field, on the ties of railroad tracks in the part of New Jersey that borders Pennsylvania, in middle of the nineteenth century. The central figure of the story is a Philadelphia naturalist named Joseph Leidy, once famous but now largely forgotten. Leidy was the first to observe our laboratory bacterium in its natural habitat, living in the intestines of animals.

Leidy's scientific legacy affects everyone, yet he enjoys almost no posthumous reputation. A nineteenth-century polymath, who was initially trained as a physician, Leidy became one of his era's greatest naturalists. He identified the nematode in undercooked pork that is responsible for trichinosis, a debilitating and sometimes deadly muscle disease. He...

Read the full article for free courtesy of your local library.