Typhus is characterized by a skin rash and high fever and has caused epidemics that killed tens of thousands in Europe from the 16th to the 19th century.
The disease is carried by type A lice, but not all type A's carry it, Reed explained.
"This might be one of the few diseases that went against the grain of colonization and spread from the New World back to the Old World," he said.
(Read related story: "Did Columbus Bring Syphilis to Europe?" [January 16, 2008].)
In future research, Reed and colleagues will examine lice found on mummies from various cultures for DNA of the bacteria that causes typhus.
"That would be the smoking gun," Reed said. "If we were able to find evidence of the disease in the Americas prior to Columbus, then we would know for sure that the origin of the disease was here."
Vince Smith is a louse expert at the Natural History Museum in London who was not involved in the new study.
He said the research "opens up a lot of possibilities for doing ancient epidemiology and epidemiological studies on the transmission of louse-borne disease."
"It's not something that we've been able to do a great deal of before, simply because it's extremely difficult to extract DNA from louse specimens that are this old. The DNA in lice tends to degrade very quickly," he added.
Reed and his colleagues also plan more studies on louse genetics to glean insights into human migration patterns.
In particular, they will look for fast-evolving genes that are likely to differ from one population to the next and use population genetics to infer when each population moved.
"We're hoping that we can sample more lice in Siberia and Mongolia, for example, and lice from mummies, especially from the Americas," he said.
Genetic connections between ancient lice in these various populations would solidify theories that the first Americans originated in Siberia and Mongolia, he noted.
"So we're scouring museum collections, looking at mummies, and trying to collect lice from them," he said.
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