Perhaps the most serious current threat to our food supply is the wheat rust fungus (Puccinia graminis). A new and highly virulent strain emerged from Uganda in 1999 and was, therefore, named Ug99. It is presently in Africa and parts of Asia. Because the spores are airborne, this fungus will inevitably spread worldwide. Breeding resistant wheat varieties is in progress but takes several years.
Overpopulation and microbial evolution
Overpopulation does not merely threaten starvation; it sets the scene for the evolution of new infectious diseases. The more people there are—and the more crowded, unhygienic, and malnourished they are—the greater the opportunity for some new and virulent plague to emerge. So far, we have kept ahead.
A related issue is the growing number of humans with deficient immune systems. Some people are immunocompromised due to drugs used to suppress rejection of organ transplants or drugs used in cancer therapy, but the vast majority are AIDS victims who are infested with a growing variety of opportunistic diseases. Some of these diseases rarely infect healthy people, but others, such as tuberculosis, sometimes infect the healthy. AIDS patients have become evolutionary staging areas where previously harmless microorganisms can adapt to growth in humans without being promptly eradicated by the immune system. As drugs keep AIDS patients alive longer, opportunistic infections get more time to grow and evolve. Long-term antibiotic treatment provides ideal conditions for antibiotic resistance to arise and perhaps spread to other bacteria that are dangerous to people with healthy immune systems.
Predicting the future
“Clearly, the future is still to come.”
—Peter Brooke, member of U.K. Parliament, 1986
Clever prophets take care to make their pronouncements ambiguous. That way, they can claim to be right about whatever happens. Moreover, it doesn’t take much insight to realize that wars, earthquakes, famine, and pestilence will make continuing appearances on the world stage.
In his futuristic work The Shape of Things to Come, published in 1933, H. G. Wells relies on a novel plague to eliminate half the population of Earth in 1955–1956 and usher in a new era. Although this epidemic was largely modeled on the Black Death, Wells had his “maculated fever” waft around the world on the wind instead of spread by fleas. His fictitious disease emerged from captive baboons in the London Zoological Gardens. The Shape of Things to Come was written as a prediction of the future in an age when most scientists foresaw only the eventual eradication of infectious disease, not its resurgence.
So what should we predict? First, let’s consider the global situation. The British Empire was the last great civilization. Improved hygiene, originating from the industrialized West, led to worldwide decreased infant mortality. That, in turn, created a population boom that undermined the profitability of the European colonial empires. Despite poor hygiene and rampant disease relative to the industrial nations, the birth rate still outstrips infant mortality in Third World countries. The ongoing population explosion is the single most important biological trend in today’s world.
Denser populations, coupled with poverty, are promoting the spread of disease. Although tuberculosis is in the lead right now, most of those infected do not fall ill. As the remaining sensitive humans are weeded out, the incidence of TB in the Third World will begin to decline naturally, just as it did in Europe a century ago.
In the advanced nations, AIDS will affect homosexuals and intravenous drug users but have marginal impact on the mainstream. Its major effect, especially in the United States, will be to increase the cost of health care in the inner cities. This will help enlarge the growing gap between rich and poor. In Africa and, to a lesser extent, other third world regions, AIDS will thin out the promiscuous and malnourished, and favor the spread of religious puritanism, particularly, Islamic sects.
Still more serious, in my opinion, are malaria and other insect-borne infections that are spreading in the tropics. Rising world temperatures promote the spread of insects that transmit many tropical or subtropical diseases. Human construction and irrigation projects are helping, as is the steady increase in insecticide resistance among the insect carriers. An ugly long-term threat is the possible adaptation of tropical viruses to be carried by insects that survive in colder climates.
Future emerging diseases
The growing Third World cities are the true danger zones for emerging disease. The threat is not so much that Ebola or Lassa might break loose in a crowded slum. More dangerous is the prospect that some disease that already has the capacity to spread effectively might increase in virulence while circulating among the tightly packed masses. A rogue variant of flu or measles that killed a higher proportion of its victims could easily sweep through a crowded Third World city. The denser such populations grow, the greater is the likelihood of such a mutant emerging and spreading.
Such a virus could spread across the world by air travel. As urban decay continues, the cities of industrial nations are gradually becoming more susceptible to such infection. One paradoxical effect of advancing technology is on air pollution. Fumes from automobiles and oil refineries kill most airborne microbes. Clean, pure air allows them to live. Reducing air pollution makes the transmission of airborne infections much easier. Centralized air-conditioning recirculates air, along with any germs it carries, among all the rooms within a building—or an airport complex.
Gloom and doom or a happy ending?
“This is the way the world ends
Not with a bang but a whimper.”
—T. S. Eliot
Until recently, most essays on infectious disease ended on a triumphant note. Human technology has taken care of the problem. Eat, drink, and be merry (at least, until you die of cancer or heart disease)! More recently, the emergence of novel infections, coupled with the problem of increasing antibiotic resistance, has heralded a move to gloom and doom. Perhaps not the next outbreak, nor even the one after that, but soon a plague will emerge that we cannot control. Civilization will collapse, and even if we survive, we will revert to savagery.
Gloom-and-doomers generally opt for a single highly virulent plague that creates unmitigated disaster. However, previous plagues rarely destroyed society as a whole. Instead, they transformed it. Even the medieval Black Death is a case in point. It fits rather well with Nietzsche’s maxim: “If it doesn’t kill [all of] you, it will make you [society] stronger.” Western society emerged improved and less restrictive.
Nonetheless, the Black Death was a terrible disaster, and we certainly do not wish to suffer a parallel experience in the mere hope of future improvement. Thankfully, although providing sufficient resources rapidly is a major problem, the advanced nations have the capacity to keep most foreseeable individual epidemics under reasonable control.
However, as global crowding and travel continue to increase, there will be steadily more novel infections. One can envisage an increasing cumulative disease burden, as opposed to a single devastating plague. In particular, we are swimming in a sea of viruses that constantly mutate. As our populations grow ever denser, we are favoring the emergence of variants of infectious agents with increased virulence.
At the same time, modern technology is spreading from the West to the rest of the world, especially Asia, and is also constantly improving. Essentially, we have become embroiled in a high-tech arms race with the rapidly mutating viruses and, to a lesser extent, with the bacteria, which change more slowly. Although we have suffered some recent setbacks, we are still winning. In most regions of the world, life expectancy and standards of living are increasing, albeit more slowly than in the twentieth century.
The two most populous nations, China and India, both have rapidly developing biotech industries. Indeed, artemisinin, the drug now most favored for treating malaria in the Third World, came from China. Although drug discovery, especially of novel antibiotics, has slowed in the West, I suspect that the emerging high-tech nations will pick up the slack rather soon.
Novel infections will
continue to emerge and test our medical technology and health care systems. If we can plot a common-sense course between getting too smug and over-reacting to every minor outbreak, I think our chances are pretty good.
Further reading
Fascinating classics written long ago that are still good reading:
Defoe, Daniel. Journal of the Plague Year. New York: New American Library, 1960. (Original edition 1723.)
Although a work of fiction, the author lived in times when the bubonic plague was still around.
Nightingale, Florence. Notes on Nursing: What It Is and What It Is Not. New York: Dover Publications, 1969. (Original edition 1859.)
For a nice little old lady, Florence Nightingale was amazingly blunt and opinionated. She made generals tremble in their shoes. She would have made Hillary Clinton wilt!
Most important modern works:
Ewald, Paul W. Evolution of Infectious Disease. Oxford: Oxford University Press, 1994.
Seminal work on the evolution of infectious disease from the modern genetic and evolutionary viewpoint. Rather academic.
Herlihy, David. The Black Death and the Transformation of the West. Cambridge, MA: Harvard University Press, 1997.
Expounds the idea that the Black Death was responsible for the emergence of Western democracy.
McNeill, W. H. Plagues and Peoples. Garden City, NY: Anchor Press, 1976.
The most important single source that summarizes and explains the idea that epidemics affected human history.
Zinsser, Hans. Rats, Lice & History. Boston: Little, Brown and Company, 1934. (Reprinted quite frequently.)
Classic on typhus fever and history from the viewpoint of a microbiologist.
Narrow in focus, yet fascinating:
Cantor, Norman F. In the Wake of the Plague. New York: Free Press, 2001.
How the Black Death remodeled European society.
Cockburn, Aidan, and Eve Cockburn. Mummies, Disease and Ancient Cultures. Cambridge, U.K.: Cambridge University Press, 1980.
Grmek, Mirko D. Diseases in the Ancient Greek World. Baltimore: Johns Hopkins University Press, 1989.
A selection of other interesting books:
Cartwright, Frederick F., and Michael D. Biddiss. Disease and History. New York: Dorset Press, 1972.
Crawford, Dorothy H. Deadly Companions. Oxford: Oxford University Press, 2007.
Diamond, Jared. Guns, Germs and Steel. New York: W. W. Norton, 1998.
Garrett, Laurie. The Coming Plague. New York: Penguin Books, 1995.
Oldstone, Michael B. A. Viruses, Plagues, and History. New York: Oxford University Press, 1998.
Preston, Richard. The Hot Zone. New York: Random House, 1994.
Wills, Christopher. Yellow Fever, Black Goddess: The Coevolution of People and Plagues. Reading, MA: Addison-Wesley, 1996. (First published in the United Kingdom by HarperCollins as Plagues: Their Origins, History and Future.)
Websites that deal with epidemics and infections:
http://www.cdc.gov/
Centers for Disease Control
http://www.who.int/csr/don/en/
World Health Organization disease outbreak news
http://www.fda.gov/Food/FoodSafety/FoodborneIllness/FoodborneIllnessFoodbornePathogensNaturalToxins/BadBugBook/default.htm
FDA site about foodborne disease
http://fas.org/irp/threat/cbw/
Federation of American Scientists on biological and
chemical weapons
http://www.ifrc.org/
Red Cross and Red Crescent on disasters, including epidemics
http://www.mic.stacken.kth.se/Diseases/
Archive on disease from the Karolinska Institute
Index
A
Abraha, 119
accidental violence, 34
Africa
disease as protection against invaders, 54
disease origins in, 13-17, 205
tropical diseases, partial resistance to, 122-123
African/African-American population, tuberculosis in, 236
agents of disease, changing, 233-234
agricultural societies, hunter-gatherer societies versus, 56-59. See also ancient civilizations
agriculture industry, consumption of antibiotics, 248
AIDS. See HIV/AIDS
air, as transmission method, 39
air pollution, 139, 254
air-conditioning, 236
airborne diseases, spread of, 254
alastrim, 214
allicin, 178
amateurs, attempts at biological warfare, 132-133
amebic dysentery
carriers of, 46
cure for, 178
origin of, 22
American Indians. See indigenous Americans
American Type Culture Collection (ATCC), 132
Amherst, Lord Jeffrey, 203
ancient civilizations. See also cities
disease knowledge of, 19
history of epidemics in, 86-90
irrigation in, 68
life expectancy in, 167
veneral disease (VD) and, 159-162
ancient religious beliefs. See also religion
disease, explanations for, 167-168
on disposal of dead bodies, 173-175
Egyptians, 170-171
expelling evil spirits, 177-178
gods of pestilence and healing, 168-169
Greeks, 171
hygiene and, 171-173
polytheism versus monotheism, 179-181
protection from evil spirits, 178-179
Roman Empire, effect of epidemics on, 166
Sumerians, 169-170
transferring evil spirits to animals, 175-177
animal diseases, human diseases versus, 22-24
animals
disease origins in, 17-24
domesticated animals, lack in pre-Columbian America, 197-198
transferring evil spirits to, 175-177
as transmission method, 39
annual mortality rate, 238
anthracite, 91
anthrax, 23
as biological weapon, 132, 135
in medieval Europe, 130
vaccine side effects, 131
vaccine strains of, 133
in World War I, 136
antibiotics
effect on sexual morality, 143
origin in fungi, 113
resistance to, 247-250
Antoninus, plague of, 87
apes, diseases from, 21-22
Apollo, 27, 166, 169, 171
Aristotle, 28
armies, large versus small, 123-124
Artemis, 171
artemisinin, 256
Asian flu of 1957, 243
Asklepios, 166, 169
Aspergillus, 105
Assyrians
expelling evil spirits, 177
mortality rate, 203
Atacama Desert, 196
ATCC (American Type Culture Collection), 132
Athens, population density, 28
Attila the Hun, 1-4, 89
Augustine (saint), 172
Aurelian (Emperor of Rome), 89
Australian rabbit population, 53, 137-138
autoimmune diseases, 228-229
avian flu, 243
Aztecs, effect of smallpox on, 200
B
Bacillus anthracis, 132-133
bacteria. See also bacterial diseases; disease
antibiotics from fungi, 113
as biological warfare, 134
mutation rate, 61
number of, 231
origin of diarrheal diseases, 70-71
plasmids, disease virulence and, 63-65
rickettsias, 208
role in food poisoning, 93
bacterial chromosome, 63
bacterial diseases. See also bacteria; names of specific diseases
antibiotic resistance, 247-250
in cities, 215
rate of evolution, 24
&n
bsp; transmission methods, 215
bacterial dysentery, cause of, 64
barbarians, effect of disease on, 89
Bartonella, 196
Bastet, 170
bats, as Ebolavirus carriers, 239
behavioral avoidance, 52
bejel, 148
beliefs. See religion
Biblical cultures, scapegoat ceremony, 175
biological isolation, 207-208
biological warfare
against indigenous Americans, 203-204
against rabbits, 137-138
agents used in, 134-135
amateur attempts at, 132-133
anthrax as, 132
cost of protective measures, 131
genetic engineering of diseases, 139
origin of, 130
psychological effects of, 131
unreliability of, 138-139
in World Wars I and II, 136-137
biology, role of, 67-68
bird flu, 243
birds
diseases from, 22
migration, effect on biological isolation, 207
birth control pills, effect on sexual morality, 143
Germs, Genes, & Civilization: How Epidemics Shaped Who We Are Today Page 24