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Spotlight   |  Spring 2006

The up side of lice

Image: The Grand Old Man book cover

Insect geneticist Barry Pittendrigh leads a research project to sequence the body louse genome in an effort to develop better methods to control the pest. (Photo by Tom Campbell)

Head lice often are the bane of parents, but it's another variety of the insect—body lice—that carries some of the most infamous and deadly diseases that have plagued people for centuries.

A team of researchers led by Purdue Agriculture insect geneticist Barry Pittendrigh is taking the first step toward sequencing the complete body louse genome. The goal of the National Institutes of Health-funded genome project is to invent new pest control methods to prevent the spread of diseases, such as relapsing fever, trench fever and typhus. The Centers for Disease Control and Prevention classifies typhus as a bioterrorism agent.

Information gained from the sequencing project also will provide clues to how the grain-of-rice-sized insects pass on infection-causing organisms to people and other animals. “If we have a relatively complete louse genome, we can do experiments necessary to discover how lice can digest human blood and transmit disease,” says Pittendrigh. “The more we learn about the biochemical workings of these tiny creatures, the greater our chance of influencing issues associated with human health.”

Body lice spread epidemic typhus by transmitting an organism called “Rickettsia prowazekii.” The disease usually occurs in areas where people have poor hygiene, especially in developing countries or in crowded places, such as jails. The disease has a 10-percent to 60-percent fatality rate, and experts say that the disease-causing organism could be used as a biological weapon.

“Currently there are no complete genomes of this type of insect, mainly because most disease-carrying species have such large genomes,” Pittendrigh says. “Body lice have the smallest insect genome known to date.”


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