The Power of Plagues. Irwin W. Sherman

hospital in Guandong Province in southern China traveled to Hong Kong to attend a wedding and became ill. He had a fever, a dry cough, a sore throat, and a headache. Unconcerned, he felt well enough to go sightseeing and to shop with his brother-in-law in Hong Kong; during that day, however, his condition worsened and he found that he had difficulty breathing. Seeking medical attention at a nearby hospital, he was taken immediately to the ICU (intensive care unit) and given antibiotics, anti-inflammatory drugs, and oxygen. These were to no avail, and several hours later he suffered respiratory failure and died. The brother-in-law, who was in contact with him for only 10 h, suffered from the same symptoms 3 days later and was hospitalized. Again, all measures failed, and he died 3 weeks after being hospitalized.

Laboratory tests for the physician (patient 1) and his brother-in-law (patient 2) were negative for Legionnaires’ disease, tuberculosis, and influenza. A third case of this severe respiratory syndrome occurred in a female nurse who had seen the physician in the ICU, and the fourth case was a 72-year-old Chinese-Canadian businessman who had returned to Hong Kong for a family reunion. He stayed overnight in the same hotel and on the same floor as the physician. (He would ultimately carry SARS to Canada when he returned home.) Patient 5 was the nurse who attended the brother-in-law, and patients 6, 7, 8, and 9 were either visitors to the hospital or nurses who had attended patient 4. Patient 10 shared the same hospital room with patient 4 for 5 days. In less than a month 10 patients had SARS, with 6 (patients 3, 4, 6, 8, 9, and 10) surviving and 4 (patients 1, 2, 5, and 7) dying. Over the next 4 months the SARS survivors sowed the seeds of infection that led to more than 8,000 cases and 800 deaths in 27 countries, representing every continent except Antarctica.

      On February 1, 2016, the World Health Organization (WHO), after recording a surge in the number of babies born with microcephaly—an abnormally small head—sounded the alarm that Zika virus was a threat to pregnant women and could cause serious harm to their fetuses. Six months later, on August 1, 2016, the Los Angeles Times reported that there were 1,638 confirmed cases of microcephaly and other neurological defects in Brazil as a consequence of the Zika virus. Worldwide, 64 countries and territories have reported to the WHO evidence of mosquito-borne transmission of Zika. There has been a steady march of the Zika virus across the Americas—an epidemic—and that is because the vector, the thoroughly “domesticated” Aedes mosquito, stays close to people and is present primarily in the Southwest and Southeast United States, as well as the Caribbean, Central and South America, and Europe. Indeed, by October 2016, according to the CDC, there were 3,936 cases in the continental U.S. and 25,955 cases in the U.S. territories of Puerto Rico, the U.S. Virgin Islands, and American Samoa. The number of cases of microcephaly may reach hundreds. The CDC director, Thomas Frieden, in an understatement, warned that without a vaccine “this is an emergency that we need to address.”

      Despite the recognition that disease, such as SARS, Legionnaires’ disease, TSS, and Zika, may appear suddenly and with disastrous consequences, more often than not little notice has been given to the ways in which disease can and has shaped history. The influence of disease on history was often neglected because there appeared to be few hard-and-fast lessons to be learned from a reading of the past; sickness seemed to have no apparent impact except for catastrophic epidemics such as the bubonic plague, or it was outside our experience. We tend to live in an age in which diseases appear to have minimal effects—we are immunized as children, we treat illness with effective drugs and antibiotics, and we are well nourished. And so our impressions of how diseases can affect human affairs have been blunted. But this is an illusion: the sudden appearance of SARS, Legionnaires’ disease, TSS, AIDS, and Zika are simply the most recent examples of how disease can affect society. Our world is much more vulnerable than it was in the past.

      New and old diseases can erupt and spread throughout the world more quickly because of the increased and rapid movements of people and goods. Efficiencies in transportation allow people to travel to many more places, and almost nowhere is inaccessible. Today, few habitats are truly isolated or untouched by humans or our domesticated animals. We can move far and wide across the globe, and the vectors of disease can also travel great distances, and, aided by fast-moving ships, trains, and planes, they introduce previously remote diseases into our midst (such as West Nile virus and SARS, influenza and Zika). New diseases may be related to advances in technology: TSS resulted from the introduction of “improved” menstrual tampons that favored the growth of a lethal microbe, and Legionnaires’ disease was the result of the growth and spread of another deadly “germ” through the hotel’s air conditioning system.

This book chronicles the recurrent eruptions of plagues that marked the past (Fig. 1.2), influence the present, and surely threaten our future. The particular occurrence of a severe and debilitating outbreak of disease may be unanticipated and unforeseen, but despite the lack of predictability, there is a certainty: dangerous “new” diseases will occur.

      Living Off Others

      The “germs” that caused SARS, Legionnaires’ disease, and TSS are parasites. To appreciate more fully the nature of these diseases as well as others and how they may be controlled, it helps to know a little more about parasites. No one likes to be called a parasite. The word suggests, at least to some, a repugnant alien creature that insinuates itself into us and cannot be shaken loose. Nothing could be further from the truth. Within the range of all that lives, some are unable to survive on their own, and they require another living being for their nourishment. These life-dependent entities are called parasites, from the Greek parasitos, meaning “one who eats at the table of another. “The business they practice, parasitism, is neither disgusting nor unusual. It is simply a means to an end: obtaining the resources needed for their growth and reproduction. We do the same—eating and breathing—in order to survive.

      Parasitism is the intimate association of two different kinds of organisms (species) in which one benefits (the parasite) at the expense of the other (the host), and as a consequence of this, parasites often harm their hosts. The harm inflicted, with observable consequences, such as those seen in Commander Peter Turner and Mary Benton and those patients afflicted with SARS and Zika virus, is called “disease,” literally “without comfort.” Though parasites can be described by the one thing they are best known for—causing harm—they come in many different guises. Some may be composed of a fragment of genetic material wrapped in protein (virus).* Others consist of a single cell* (bacteria, fungi, and protozoa), and some are made up of many cells (roundworms, flatworms, mosquitoes, flies, and ticks). Some parasites, such as tapeworms, hookworms, malaria, and HIV, as well as the Zika and Ebola virus, live inside the body, whereas others (ticks and chiggers) live on the surface. Parasites are invariably smaller in mass than their host. Consider the size of malaria, a microparasite, and hookworm, a macroparasite. Both produce anemia, or, as one advertisement for an iron supplement called the condition, “tired blood.”

Figure 1.2 The Plague of Ashod by Nicolas Poussin (1594-1665).

      The painting probably represents bubonic plague since rats are shown on the plinth

      A malaria parasite lives within a red blood cell that is 1/5,000 of an inch in diameter. If only 10% of your blood cells were infected, the total mass of the malaria parasites would not occupy a thimble, and yet in a few days they could destroy enough of your red blood cells that the acute effects of blood loss could lead to death. In effect, you could die from an internal hemorrhage. Although the “vampire of the American South,” the bloodsucking, thread-like hookworm, is only 0.5 in. in length and 0.05 in. in girth, if your intestine harbored 50 worms, you would lose a cupful of blood a day. Yet the entire mass of worms would weigh less than 5 hairs on your head.

      Some parasites have complex life cycles and may have several hosts. In malaria the