Unlike AIDS, Says a Historian, Ancient Plagues Swept the World Scythelike and Suddenly

updated 10/12/1987 AT 01:00 AM EDT

originally published 10/12/1987 AT 01:00 AM EDT

As the nationwide death toll from AIDS creeps upward, fear has evoked the phrase "modern-day plague." William McNeill, author of Plagues and Peoples, a ground-breaking 1976 study of the impact of epidemics in history, believes the term is appropriate. Yet he feels there are some important distinctions to be made between AIDS and plagues of the past. A retired University of Chicago history professor, McNeill, 69, lives with his wife, Elizabeth, in Colebrook, Conn. He discussed pestilences past and present with Chicago bureau chief Giovanna Breu.

How does AIDS compare with the plagues of old?

In the epidemics of antiquity and early modern times it was not unusual for as much as a quarter of the local population to die in a bad year. Nothing close to that has yet happened with AIDS. If the doctors aren't able to stop it, conceivably such proportions would be reached, but not for at least another 15 or 20 years. So AIDS is different in that way.

Does it differ in other ways?

AIDS comes on much more slowly. The precariousness of life is much more obvious when you're well one day and dead 72 hours later. That is the way it used to be with cholera and bubonic plague. Our ancestors lived in a world in which they never knew from month to month or day to day whether some lethal disease would strike them tomorrow, and not infrequently it did. From 1300 to 1750, when epidemics probably crested in frequency, practically everybody in the course of his lifetime experienced an epidemic in which, three or four weeks after the outbreak, a quarter, a third or even half the population would be dead.

Do you think AIDS will reach that level?

The future is as hidden to me as it is to anyone else. The historical analogue for AIDS is, I think, syphilis, which appeared outside Naples, Italy, in 1494 and within 20 years spread throughout the civilized world. At first, syphilis had what is known as fulminating symptoms—people tended to die of it quite quickly. Over the next 200 years the organism and the human population became more nearly adapted, so that people didn't die right away. At that point, death from syphilis would take 15 to 20 years. That seems to be a general pattern with infections. It may take perhaps six generations for human resistance and the organism's own mutations to reach equilibrium.

How did syphilis affect society?

For one thing, it killed off a lot of royal families and had large political consequences. After 1566 the Ottoman sultans of Turkey were incapacitated by syphilis and became mere figureheads for their high officials. In France, at the same time, the ruling Valois family became syphilitic and infertile. Uncertainty about succession contributed to the civil wars of the period. The inability of royal and aristocratic families to give birth to healthy children accelerated social mobility, making more room at the top of society than there would have been otherwise.

How did syphilis change social mores?

It seems to me that the great upsurge of puritanical feeling in the 16th and 17th centuries, which occurred in the Catholic church as much as in the Protestant faiths, could hardly have occurred without the fear that syphilis brought to sexuality. The fear of infection and the religious reinforcement of monogamy retarded the propagation of the disease. People who behaved monogamously were less likely to get it and more likely to have children. If the doctors don't find a cure for AIDS, I suspect we'll get a similar resurgence of monogamous behavior, and as that happens exposure to AIDS will decrease.

When in history did plagues first occur?

Around 2,500 B.C. we begin to get references to sudden outbreaks of disease, though we don't know what they were. The most famous biblical reference is to when the Assyrians laid siege to Jerusalem, suffered some sort of disease and had to withdraw in 701 B.C.

Haven't there always been plagues?

Not always. Up to half a million or so people are necessary simply to keep these viruses going. Until you had societies in which that many people were in some kind of contact with one another, you could not have crowd diseases such as smallpox, bubonic plague, influenza and measles. Religious pilgrimages, the advance of armies across continents, the rise of commerce and transport are other factors that spread infections. Disease is one of the fundamental factors in the decay of the Roman Empire. After Roman soldiers returned from Mesopotamia, up to half the population of the empire died of epidemics, probably measles and smallpox, in 165 and 251 A.D. In the cities, as people died, commerce halted and record keeping faltered. The military was weakened, leaving the empire vulnerable to the barbarian invasions that began just before the second epidemic.

How did you become interested in plagues?

In writing a book of world history, I had gotten to the story of how Cortez and the remains of his army were driven out of Mexico City by the Aztecs in 1521. A week later the people ruled by the Aztecs offered to join Cortez. I couldn't understand that until I saw a passage mentioning that smallpox had broken out in Mexico City. Cortez and his men had some immunity to the virus, which they had brought with them from Spain. The natives had no resistance to it. At the time they would have assumed the lethal disease was a punishment from God for attacking Cortez. The Indians took it as proof of the superiority of the Spaniards, and that furthered the spread of Spanish culture, religion and government throughout the Amerindian world.

When was the last great epidemic?

The flu epidemic of 1918-19. Very few people realize that 20 million people died worldwide, nearly three times the battle casualties of World War I. Interestingly, it may have been the confluence of American, European and African troops in France at the end of World War I that provided the milieu for the emergence of a new and unusually destructive flu strain.

Have the old plague diseases all been eliminated?

For the most part. Vaccination has eliminated smallpox. Gamma globulin injections have made measles unimportant. Penicillin knocks out bubonic plague at once. Most diseases bred in water, such as cholera, were taken care of by modern sewage systems. Tuberculosis can't be fully mopped up because the organism is so good at adjusting to the antibiotics, but it's effectively under control.

Are there likely to be new plagues, apart from AIDS?

What is certain is that stability is not the norm in the relationship between humanity and diseases. A deadly new flu strain could conceivably arise. We are still, as we always have been, exposed to the possibility of a new infectious agent making an inroad upon human populations. Ingenuity, knowledge and organization can alter, but cannot cancel, humanity's vulnerability.

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