Germs, Genes, & Civilization: How Epidemics Shaped Who We Are Today

by David P. Clark

  Half a century later, the Australians deployed a virus. The first year, myxomatosis killed more than 99% of the rabbits it infected. Ten years later, it killed only 20%. The tiny proportion of resistant rabbits who survived the first onslaught did what rabbits do best—they produced lots more rabbits. In short, the Australians selected for the evolution of a myxomatosis-resistant rabbit. Today the rabbit population is booming again and the Australians are ready for another round of germ warfare. Rabbit calicivirus emerged in China in 1984 and spread from there to Europe, Africa, and America. It showed its virulence by killing 64 million rabbits on rabbit farms in Italy. The virus spreads among domestic rabbits and then escapes into local populations of wild rabbits. The virus is highly specific and affects only European rabbits (these are often found on other continents, like the rabbits that plague Australia). The fatality rate is about 95%.

  Coordinated release of the virus at 200 to 300 sites in Australia was arranged. The Australians hoped this would minimize the emergence of genetically resistant rabbits or of milder virus. Calicivirus release in the drier parts of Australia (Western Australia, Northern Territory, and South Australia) resulted in a 95% death toll within a few weeks, much as expected. In other areas, eradication has been more erratic. The Australians might gain a few years’ respite, but the 5% survivors will not take long to rebuild a rabbit population that will be resistant to calicivirus.

  Germ warfare is unreliable

  Perhaps one reason the major nations so readily agreed to outlaw germ warfare is that it is ineffective. In practice, bullets and bombs are easier to produce and handle than biological weapons. Another issue is that even the fastest diseases, such as pneumonic plague, take at least 24 hours to kill. And 24 hours is plenty of time for a retaliatory nuclear exchange. Another drawback is the problem of delivery. Spraying is the standard method of distributing germs. Unfortunately, this relies on the weather. First, a breeze is needed—and second, the wind must blow in the right direction!

  During the 1950s, the British government field-tested harmless bacteria. When the wind blew the germs over “healthy” farmland, most airborne bacteria survived and landed alive and well. In contrast, when the bacteria were blown over industrial areas, especially oil refineries, the airborne bacteria were wiped out. Many airborne industrial pollutants are lethal to bacteria and viruses. Even if the wind is favorable, most of the population of an industrial nation is found in cities, protected from airborne germs by air pollution!

  Genetic engineering of diseases

  Let’s take a harmless laboratory bacterium, such as Escherichia coli, and make it dangerous. We insert genes for invading human cells. We provide genes for tearing vital supplies of iron away from blood cells. We add genes for potent toxins that kill people in tiny doses. What have we made? An unstoppable disease that will wipe us from the face of the Earth? No, we just converted Escherichia coli into its near-relative, Yersinia pestis, the agent of bubonic plague. The reason we are not all dying of the Black Death today is not due to any lack of virulence by Yersinia pestis, but to modern hygiene. Improving diseases by genetic engineering is of minor significance. What we should really worry about is being in Mother Nature’s gun-sights. Any army that neglects hygiene is crying out for disease to thin its ranks. We don’t need “new and improved” diseases: Any of the old favorites could handle the mission, given favorable conditions.

  7. Venereal disease and sexual behavior

  “That depends, my lord, whether I embrace your mistress or your principles.”—John Wilkes (1727–1797), replying to Lord Sandwich, who had just told him that he would die either of the pox or on the gallows.

  Venereal disease is embarrassing

  In recent times, there has been a tendency to replace the ugly term VD (venereal disease) with the supposedly less embarrassing STD (sexually transmitted disease). Despite this, accurate data on the frequency of venereal disease is hard to obtain, even in advanced nations. The reason is obvious enough: embarrassment.

  The history of venereal disease suggests that, over the long term, periods of promiscuity might alternate with periods of puritanism. Diseases transmitted by direct personal contact tend to grow milder over time, as explained in Chapter 3, “Transmission, Overcrowding, and Virulence.” Venereal diseases clearly fall into this category, and syphilis is the classic example. When a new venereal disease emerges, there is often an initial highly virulent phase that affects the more promiscuous members of society. Many victims die or are crippled or disfigured. Sterility often results. Babies are born with congenital infections or deformities. Historically, these effects have been typically viewed as punishment for sin.

  This, in turn, incites a major response in social behavior, generally couched in religious terms. The religious authorities and moralizers of the day condemn and castigate sexual licentiousness. A variety of restrictions and regulations are often put into place in the name of God or moral purity. Such restrictions themselves probably have little effect, apart from driving forbidden sexual practices underground. During England’s Victorian era, respectable middle-class people suffered palpitations at the sight of an exposed female ankle, and some went to the absurdity of covering the exposed legs of wooden furniture with drapery. Yet estimates suggest that as many as 20% to 25% of the female population of Victorian London practiced prostitution at some time during their lives. Admittedly, most took part only for short spells, to tide themselves over during periods of economic hardship. According to W. O’ Daniel, Ins and Outs of London (1859), based on police and council records, some 55,000 to 80,000 women were engaged in prostitution at any given time. This was approximately 7% of the female population. (The total London population in those days was around two million.) Historical snippets such as this show that the “good old days” when “traditional morality” supposedly prevailed are largely based on superficial appearances.

  Eventually, most venereal diseases decline in virulence and, although they may continue to spread, provoke far less fear. Sermons are muted and regulations are relaxed. The last Puritan epoch was the age of syphilis. It began shortly after the discovery of the New World, when syphilis appeared in Europe and lasted until World War II, when penicillin provided a cure. The postwar sexual liberation boom was muted by the appearance of AIDS in the 1980s. This disease is incurable and lethal, and the possibility of an effective vaccine is remote. However, treatment with expensive antiviral drugs can keep AIDS under reasonable control, at least in advanced nations.

  This alternation of puritanism with complacency will presumably continue as long as our planet’s biodiversity provides a steady supply of novel sexually transmitted diseases. Of course, complications arise. Fluctuations from promiscuity to puritanism and back are characteristic of urban cultures in which sexual morality becomes interwoven with changing fashions in political ideology and religion. Rural cultures tend to fluctuate less in their moral outlook. Economic conditions also have major effects. Thus, the relative area of female body surface exposed to view in Western capitalist society follows the economic cycle. When the economy booms, more skin is exposed; when recessions come, female fashions become less revealing.

  Technological advances have also changed sexual behavior. Birth control pills have vastly reduced the risk of pregnancy following sex. The more recent RU486 (the “abortion pill”) has reduced the health risk and cost of dealing with unwanted pregnancies. Antibiotics have effectively cured the traditional venereal diseases, syphilis and gonorrhea. All these advances have tended to make sex less risky.

  Promiscuity, propaganda, and perception

  Have the last century’s medical advances really increased the frequency of casual sex? Or by reducing the damage caused, have they just reduced social disapproval? Does puritanism decrease promiscuity or merely drive it underground? Consider that, despite having much higher church attendance and more religious zealots, the United States has a vastly higher incidence of most sexually transmitted diseases than Western Europe.<
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  Recent studies suggest that rates of venereal disease in the United States are up to 50 to 100 times greater than in other industrial nations. Thus, around 150 in 100,000 Americans have gonorrhea, compared to 3 in 100,000 in Sweden and 19 per 100,000 in Canada. Such figures typically generate calls for education and moral leadership. Both gonorrhea and syphilis declined significantly in the United States during the 1990s. Sadly, this trend reversed from 2000 onward, and both infections have been slowly but steadily increasing in incidence.

  Is promiscuity really more common nowadays than, say, in Victorian times, or is it merely less stigmatized? In Victorian England, unmarried mothers routinely moved to a new town and explained their lack of a husband by posing as “war widows.” As long as infectious disease cooperated in killing off a steady proportion of the troops Britain sent overseas to control its Empire, this disguise was not only credible, but patriotic. Despite the stories our self-righteous age routinely tells of Victorian prudery and the unfeeling treatment of unmarried mothers, those who pursued the patriotic path often received plentiful help and charity. This scheme also allowed unmarried mothers to “remarry” without fuss. We should realize that most intelligent Victorians were well aware of the war-widow ploy. As long as moral convention was not publicly flouted, few cared about unmasking fakes.

  The great problem with studying sexual behavior, let alone its more squalid aspects such as the spread of venereal disease, is locating the reality beneath the veneer of social pretense. Both respectability and promiscuity have their pretensions. Men of the world boast of conquests they’ve never made, while respectable folk deny involvement in whatever current moral conventions disapprove of. Researchers attempting to draw attention (and funding) exaggerate sexual aberrations, and political activists inflate the numbers of homosexuals. Both traditional religious believers and feminists tend to exaggerate the number of child molesters, especially when novel phenomena such as Internet chat rooms are involved. So don’t take the information in this chapter overly seriously. Information on venereal disease is much less reliable than it is for less embarrassing diseases.

  The arrival of syphilis in Europe

  The writings of Hippocrates, a little before 400 B.C., suggest that herpes, chlamydia, and possibly gonorrhea were circulating in Greece and the Middle East at this time. Chlamydia can cause both venereal disease and trachoma, an eye infection often leading to blindness that was especially common in ancient Egypt. Other diseases can have symptoms similar to gonorrhea, so historical descriptions are mostly ambiguous. John of Ardenne gave the first unambiguous descriptions of gonorrhea in England in 1378. Cases were frequent from then on. The ancient world did not have AIDS, nor did it have syphilis, which was brought back from the New World by Columbus and other explorers.

  The “typical” cycle for the progress of a venereal disease is largely derived from the history of syphilis. Syphilis almost certainly came from the Americas. Its European debut was among French soldiers assaulting Naples in 1494, just two years after Columbus sailed. The returning French army took it back to France, where it spread rapidly among both rich and poor. The physicians of the day apparently did well out of it. A monk, seeing Thierry de Hery praying on his knees before the statue of Charles VIII of France, remarked that the king was not a saint. “Perhaps not, but I shall never be able to thank him enough for having introduced into France the sickness by which I have made my fortune,” replied the doctor. From France, syphilis spread throughout Europe, Asia, and Africa.

  Venereal diseases are typically named after a nearby nation that is disliked. Most Europeans called syphilis the “French pox.” When syphilis arrived in the Far East it was called Guangchuang (Canton ulcers) by people in other parts of China, and “Chinese pox” by the Japanese. The Bible mentions the “Egyptian botch,” and although we no longer know what this refers to, the racial slur suggests an ancient venereal disease. This tendency has caused considerable confusion. In the days before syphilis reached Europe, the term “French pox” was often used, at least in England, to refer to gonorrhea.

  When syphilis first appeared, it showed two notable characteristics. First, it was highly virulent. Second, its transmission was not limited to sexual means. In some ways, syphilis behaved in Europe like smallpox in America. The American Indians had no prior exposure to smallpox and were highly susceptible. The same was true of Old World inhabitants facing syphilis. Serious symptoms appeared rapidly after infection, and syphilis was often fatal or severely crippling. Note that the whole French army was forced to withdraw from Naples because of so many rapid casualties from syphilis! Over the centuries, syphilis became milder and the disease progressed more slowly. In many patients, it no longer reached its debilitating tertiary stage, and in those unlucky few, it took many years to do so. One of these was America’s most famous criminal, Al Capone, who died in jail of syphilis in 1947, aged 48.

  For 40 years, from 1932 to 1972 the U.S. Public Health Service carried out a long-term study of syphilis in black men in Tuskegee, Alabama. Although penicillin, which cures syphilis effectively, became available in the 1940s, the roughly 400 patients were denied treatment to observe the long-term effects of syphilis. It wasn’t just Hitler’s SS who carried out medical experiments on the racially despised. The relative mildness to which syphilis had sunk is illustrated by this trial that lasted for 40 years, longer than the average life expectancy in 1494.

  Similar declines into mildness can be seen in other venereal diseases, including gonorrhea and chlamydia. In 1475, Edward IV returned to England after a campaign in France. He noticed the damage caused to his army by gonorrhea. He complained that he “lost many a man that fell to the lust of women and were burned by them, and their penises rotted away and fell off and they died.” It is clear from this graphic description that gonorrhea was much nastier then than now. However, even then, gonorrhea was in decline. Although it still picked off promiscuous stragglers, it was no longer capable of determining the overall outcome of a military campaign.

  Relation between venereal and skin infections

  Syphilis is caused by the spirochete Treponema pallidum. Spirochetes are spiral bacteria often found in freshwater or in the intestines or on the skins of assorted animals, including man. Most are harmless. Treponema is a skin-dwelling spirochete that has learned how to invade the body and cause disease. Four types of infection are due to Treponema: yaws, pinta, bejel, and syphilis. All are passed along by physical contact. Yaws is a tropical skin disease that sometimes penetrates the internal organs, where it causes serious damage that can eventually be fatal. Bejel is a variant adapted to drier conditions and is frequent in the Middle East and North Africa. Pinta is a milder form seen largely in Central and South America.

  Precontact infections of Treponema in the Americas seem mostly to have been mild and nonvenereal. The form of Treponema that came to Europe in the 1490s was probably intermediate between yaws and syphilis. The earliest European cases were probably transmitted as often by nonsexual contact among dirty crowded soldiers as by sexual contact. Yaws has continued to infect skin surfaces where hot, moist conditions prevail. Syphilis adapted to the colder European climate by colonizing a hot, moist region of the body and so became specialized for sexual transmission.

  A similar relationship is seen between the skin disease trachoma and genital chlamydial infections, both caused by Chlamydia trachomatis. Trachoma is a disease of the body surface, notable for infecting the eyes and causing blindness in severe cases. It is spread by flies, as well as dirty hands. Chlamydia is the second most common cause of genital infections today (human papillomavirus, HPV, is the first). Although complications can occur, genital Chlamydia is usually mild and often symptomless. A 1997 survey of 10,000 sexually active American teenagers revealed that 8.6% of the girls and 5.4% of the boys had Chlamydia. More recent, but smaller, surveys suggest moderate improvement. Nearly all the males and 75% of the females had no noticeable symptoms. Cold sores on the skin and genital infect
ions caused by Herpes virus are another such pair of diseases caused by variants of the same infectious agent.

  Some early Indian texts from 100–200 A.D. mention a “kustha roga” disease that could well be leprosy. Interestingly, they suggest its spread was at least partly sexual. Some medieval European writings refer to lepers as being lecherous and depraved. The historical evidence by itself is unconvincing, but the tendency of skin diseases to generate venereal variants is quite marked. Was there once a venereal version of leprosy?

  AIDS is an atypical venereal disease

  Unlike the venereal diseases discussed already, AIDS (acquired immune deficiency syndrome) is not derived from a skin infection. HIV (human immunodeficiency virus), the agent that causes AIDS, is bloodborne and is transmitted both by sex and by dirty needles. Partly because of this, in advanced nations, AIDS is confined to a small sector of the population. The AIDS epidemic has probably peaked in the industrial nations but is now the biggest killer among infectious diseases in the Third World, especially in Africa, where it has overtaken both malaria and tuberculosis.

  AIDS is not the only bloodborne venereal disease. Several types of viruses cause hepatitis. About one-third of the cases are due to hepatitis B virus, which spreads by the same mechanisms as AIDS and is prevalent among the same high-risk groups. Many cases of hepatitis B are very mild, and natural recovery occurs after a week or two. Other patients suffer fatal liver failure or long-term liver damage. Several other viruses, some only recently observed, behave similarly. Luckily, hepatitis viruses do not damage the immune system or mutate as rapidly as AIDS. For some viral infections, including hepatitis B, effective vaccines are now available.