For the last week and a half, the same plague which cut Northern Europe's population to nearly a half in the 14th century has ravaged a large India industrial center, raising questions on how apparently vanquished diseases reappear.

On September 22, the bubonic plague took its first confirmed death in Surat.

Within two days, the "black death" had claimed 24 more victims and put 137 others in the hospital. By the 24th, about 200,000 had fled Surat to New Delhi or surrounding cities. In total, the plague may have killed about 300 people.

To those living far from Surat, however, bubonic plague connotes history rather than reality. Most have heard of the Black Death which afflicted Europe in the 13th and 14th centuries. Public health officials thought the final epidemic hit in the late '60s. In fact, a prominent biologist stated with pride in 1975, "During the last 150 years the Western world has virtually eliminated death due to infectious disease."

Biologists based their optimism on the effectiveness of antibiotics. According to an article in the American Scientist, smallpox, tuberculosis, polio and all other major infectious diseases were considered nearly eradicated by 1975.

That same year, however, saw the first of the diseases to come--with the outbreak of Lyme disease. Legionnaire's disease emerged in 1978, toxic-shock syndrome in 1978, AIDS in 1983, and chronic-fatigue syndrome in 1985, to name a few. Malaria re-emerged. Today, dengue and yellow are spreading. Instead of improving, the virulence of disease seems only to have entered a new stage.

Public health officials in the '90s are looking to understand low these new diseases emerge, and how long-deal pestilences like the plague come back.

They find a complex picture. On the one hand, the modern world fights disease with better treatment than ever before. On the other, byproducts of modernization, like rapid transportation, can spread epidemics world-wide.

The current outbreak in India demonstrates a combination of old and new factors. Surat shares at least one condition with Medieval Europe--lots of garbage.

The proper method of garbage disposal in the Middle Ages was throwing it out of the open window. Outside, the communal pigs fed in the streets. In fact, the tradition of a male accompanying a female arm in arm down the street was to protect her from flying bones and slops.

In Surat roughly one half of the 12.5 million population lives in shantytowns outside city sanitation control. In addition, a ten foot monsoon flood in August strew sewage everywhere.

The bubonic plague comes from a bacterium called yersinia pestis which lives in rats. In a dense population of humans and rats, fleas can transfer the bacteria through their bites between the species.

It was this type of plague that initially broke out in India. Sufferers experienced the same swollen lymph nodes from which bubonic plague derives its name in Medieval French.

The disease soon changed to the pneumonic variety, by far the deadlier of the two. The bacteria which carry pneumonic plague can be transmitted through water droplets from the lungs of humans--that is, whenever people sneeze. This can bring the disease to epidemic proportions as the bacteria travel from person to person through the air, as happened in Surat.

These conditions can be improved with modern technology. The Indian government has sent hundreds of tons of DDT to kill the fleas. Workers are clearing the piles of garbage. The hospitals order by e-mail millions of tablets of antibiotics. Under treatment, the 50% survival rate of the plague increases to almost 100%.

"The situation," said Health Minister of State Harsh Vardhan, "can be controlled in two to three weeks."

But although modernization offers the means to control epidemics, disease springs from modernization gone awry. In Surat, for example, rapid industrialization and growth has created communities outside the control of the city administration.

Martha Chen, research associate at the Harvard Institute of International Development, said that the epidemic had been caused by "break down of infrastructure, especially due to urban population growth."

"What comes with all this growth is communities outside health and sanitation services," she said. "It's a case where the government is simply overstretched."

Disease seem always to spring from disruption in the accustomed order. Lyme disease, for example, was caused by the overpopulation of deer which followed a change in the habitat.

Modernization May Hurt

As the world undergoes the accelerated change of modernization, opportunities for disease may only increase. The disruptions caused by large movements of people and goods illustrates one way disease spreads.

Surat is one example of many people brought together hurriedly. Cholera arrived in South American in 1991 in the bilge water of a freighter. A more recent example of cholera attack appears in the migration of 20,000 Rwandans to Zaire two months ago. The result of a massive disruption in demography was an epidemic of cholera.

Although these diseases can be treated, as Warwick Anderson, assistant professor of the history of science, notes instead of just treating diseases, public health officials should aim to prevent the conditions that caused them in the first place.

In fact, excessive use of antibiotics could cause bacteria to become resistant, according to Dr. Lincoln Chen, professor of international health at the School of Public Health. For example, he says, a strain of malaria developed which was immune to the treatment.

Old diseases re-emerge because in general they lielatent in the animal population. In a sample of 247 infections, Will Kastens of the School of Public Health discovered that 180 were shared by animals. The bubonic plague is an example, and will probably prove impossible to eradicate.

Inhabitants of Boston may enjoy good sanitation and little contact with rats, but disease could arrive from anywhere in the world in less than twelve hours by airplane. In fact, a flight arrives from India twice a week in Logan airport. Airports in the Middle East have even prohibited all flights from India to prevent spread of the plague.

Nevertheless, it is unlikely that the plague would hit Boston, since it would probably surface during the nearly twenty-hour-long trip. In general air travelers have the wealth to afford the treatment necessary to control contagion, according to Lincoln Chen.

Researchers suggest instead that we look to the sea for epidemics. The city of Boston pours tons of pollution and sewage into the water, causing change to the ecosystems. Already algae bloom points to a very unbalanced environment. Perhaps some vicious bacteria is breeding in the sewage, waiting to spread infection by a carrier as apparently innocent as a flea.