The Black Death that ravaged 14th Century Europe was almost certainly not the Bubonic Plague as originally thought, new research from a group of Penn State and University of Washington anthropologists suggests.

Relying on bishop's records from several English dioceses and the expertise of medical geographer Stephen Matthews, associate professor of demography, the team mapped the spread of the Black Death and noted several anomalies.

James Wood, professor of anthropology and demography, explained that if the Black Death was a zoonosis -- a disease originating in animals -- it would not have spread as rapidly. Since the vectors for the Bubonic Plague are rats carrying infected fleas, the pathogen would first affect the rat population of an area, then move to humans.

Based on the maps Matthews created, the researchers found that barriers that would normally disrupt the migration of rats, such as rivers or mountains, did not disrupt the spread of Black Death.

"The disease spread across England like wildfire," said Sharon DeWitte-Avina (graduate-biological anthropology). In comparison, she added, the Bubonic Plague spreads slowly.

The diocesan records also indicated that the mortality of the disease was many times greater then the plague.

"We looked at the dioceses of Lincoln [England] and monthly mortality rates were 35 to 45 times higher than Bubonic Plague," DeWitte-Avina said.

The researchers are not sure what caused the deaths of more than two million people in the years between 1347 and 1350. However, they maintain the symptoms described for the Black Death are too nonspecific.

Rebecca Ferrell, a post-doctoral candidate in biological anthropology, said in comparing historic accounts of symptoms from the Black Death and modern descriptions of the Bubonic Plague, the main symptom the two share is buboes, which are huge, grotesque growths caused by lymphatic swelling. She added that there are many different diseases that cause the lymph glands to swell.

There are several other symptoms of Black Death found in historical documents that are not common with Bubonic Plague, Ferrell said, including subcutaneous hemorrhaging, fetid breath, foul body odor and coughing and vomiting blood.

The next step for the team in its research is to obtain a Black Death skeleton, Wood said. The team hopes to recover DNA for molecular analysis of the pathogen in the anthropology department's genetics laboratory, used for analysis of ancient DNA.

To do this, Wood said the team needed a methodology for identifying the pathogen. He said normally, biologists have a primer, or specific bacteria, to base their study on. Since the team is trying not to rule out any possibilities as to what caused the Black Death, it needs a more generalized way to conduct their investigation.

"The techniques that are being used in the lab are improving rapidly," DeWitte-Avina said.

Information obtained from the molecular analysis will give the group clues as to how pathogens evolve.

Ferrell said bacteria changes much faster then humans do over time, and admits to the possibility that the disease they find might be radically different from any pathogen that exists today.

The group's research on the Black Death began in a seminar on infectious diseases that Wood taught in the spring of 1998.

They relied mainly on bishop's registers that document, among other things, the replacement of local priests, for reasons including death.

The group compiled information of the location and date of deaths that appeared to be Black Death in spreadsheets. This information was then given to Matthews who mapped the spread of the epidemic month by month.

Matthews said the process of mapping the epidemic is continuous, as the team finds more data on deaths, he integrates it and creates a new map.

It was not until last year, when they obtained an unpublished register from a historian in England, that they were able to really get moving, Wood said.

"The unpublished register is the only surviving bishop's register that had date of death," he said.

The researchers used the registers because they were some of the most systematic records kept at the time, due to widespread illiteracy.

"There is some question as to how priest mortality represents all mortality," Ferrell said. However, she added that because priests were most likely in contact with the peasants of the time, their death rates would probably correlate to them.

"It's not a bad proxy for what was happening in the whole population," Ferrell said.

Wood agreed, adding that priests were probably living in the same conditions as peasants.

The group, which also includes Mark Shriver, associate professor of demography, and Darryl Holman, assistant professor of anthropology at the University of Washington, will publish their research in a book in 2004.

"The Black Death significantly altered human history," Ferrell said. She added later that it was fun to go back and reanalyze records in order to make a meaningful statement about an interesting event in history.

With the concern about bioterrorism and infectious diseases in general, Matthews said that the group's research is relevant to society as a whole.

"I think it is very important in general, because we don't know enough about infectious diseases," Matthews said.