From Plague to Leprosy: 7 Diseases We'd Forgotten About


The bubonic plague, leprosy and polio are thought of as diseases of the past -- things that might have had a part in history, but aren't around to infect us any longer.

But a recent incident in China, where a town was quarantined for 10 days after three people died of a variant of bubonic plague, was just one of many reminders that these diseases have not vanished from the face of the earth.

While many think of these diseases as completely eradicated -- and they occur far less frequently than they used to in the United States -- they have managed to hang on.

"The microbes have hopes, dreams and aspirations just like human beings. In their case, it's to infect other people," said Dr. Howard Markel, a pediatrician and medical historian at the University of Michigan.

Smallpox was the first disease for which a vaccine was developed. While the British doctor Edward Jenner gave the first injection in 1796, the World Health Organization did not declare the disease eradicated until 1980.

But replicating the success of the smallpox effort with any other disease has yet to happen.

"There are a number of diseases about which we hear very little in this country but prospects for actually eliminating/eradicating any of them are slim," said Dr. D. A. Henderson, author of "Smallpox: the Death of a Disease," who led the WHO's initiative to eradicate the virus.

Other diseases, he said, present challenges not faced with smallpox.

"Why not the others?" Henderson said. "Some, because there is an animal reservoir, like plague, or long-term carriers of the disease who can excrete the organism -- tuberculosis and leprosy -- or diseases for which the vaccine is inadequate to accomplish what we would like to achieve -- diphtheria and, to some degree, polio. It is not a simple subject to address."

For some of these diseases, treatment is difficult to administer because of the economic conditions of people suffering from the disease.

Emerging infections -- such as bird flu and SARS -- command headlines, but many other diseases still plague humans around the world, if not generally the United States.

"There's a group of infections that have been with us forever," said Dr. Peter Hotez, professor and chair of the department of microbiology, immunology and tropical medicine at George Washington University, who calls them neglected infections -- because they are often ignored, or biblical diseases, because ancient accounts describe their presence.

"Most of these neglected infections or biblical diseases occur more in rural settings than in urban settings," he said. "You will always find these diseases wherever you find extreme poverty, and that is the most common determinant."

In the following pages, we present seven infections from the past that still plague us today.

Pneumonic/Bubonic Plague

The pneumonic and bubonic plagues are caused by the bacterium Yersinia pestis, the difference being that pneumonic plague can spread from person to person -- without infected fleas.

While the pneumonic form struck China earlier this month, bubonic plague still persists in the United States, in the Southwest. Wild rats and fleas carry the disease, and when in proximity to humans, fleas will spread it to them rather than simply among rats.

"The U.S. reports around a dozen cases a year," Hotez said.

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