Free The Coming Plague by Laurie Garrett Page A

the disciplines. By the time hemorrhagic fever broke out in Bolivia, a very artificial set of distinctions had developed between the fields. Plainly put, larger microbes were considered parasites: protozoa, amoebae, worms. These were the domain of parasitologists.
    Their scientific realm had been absorbed by another, equally artificially designated field dubbed tropical medicine, which often had nothing to do with either geographically tropical areas or medicine.
    Both distinctions—parasitology and tropical medicine—set off the study of diseases that largely plagued the poorer, less developed countries of the world from those that continued to trouble the industrialized world. The field of tropical medicine did so most blatantly, encompassing not only classically defined parasitic diseases but also viruses (e.g., yellow fever and the various hemorrhagic fever viruses) and bacteria (e.g., plague, yaws, and typhus) that were by the mid-twentieth century extremely rare in developed countries.
    In the eighteenth century the only organisms big enough to be studied easily without the aid of powerful microscopes were larger parasites that infected human beings in some stage of the overall life cycle of the creature. Doctors could, without magnification, see ringworms or the eggs of some parasites in patients’ stools. Without much magnification (on the order of hundreds-fold versus the thousands-fold necessary to study bacteria) scientists could see the dangerous fungal colonies of Candida albicans growing in a woman’s vagina, scabies acariasis roundworms in an unfortunate victim’s skin, or cysticercosis tapeworms in the stools of individuals fed undercooked pork.
    As British and French imperial designs increasingly in the late eighteenth century turned to colonization of areas such as the Indian subcontinent, Africa, and Southeast Asia, tropical medicine became a distinct and powerful science that separated itself from what was then considered a more primitive field, bacteriology. Science historian John Farley concluded that what began as a separation designed to lend parasitology greater resources and esteem—and did so in the early nineteenth century—ended up leaving it science’s stepchild. 16
    Ironically, parasites, classically defined, were far more complex than bacteria and their study required a broader range of expertise than was exacted by typical E. coli biology. Top parasitologists—or tropical medicine specialists, if you will—were expected in the mid-1960s to have vast knowledge of tropical insects, disease-carrying animals, the complicated life cycles of over a hundred different recognized parasites, human clinical responses to the diseases, and the ways in which all these factors interacted in particular settings to produce epidemics or long periods of endemic, or permanent, disease.

    Consider the example of one of the world’s most ubiquitous and complicated diseases: malaria. To truly understand and control the disease, scientists in the mid-twentieth century were supposed to have detailed knowledge of the complex life cycle of the malarial parasite, the insect that carried it, the ecology of that insect’s highly diverse environment, other animals that could be infected with the parasite, and how all these factors were affected by such things as heavy rainfall, human migrations, changes in monkey populations, and the like.
    It was known that several different strains of Anopheles mosquitoes could carry the tiny parasites. The female Anopheles would suck parasites out of the blood of infected humans or animals when she injected her syringe-like proboscis into a surface capillary to feed. The microscopic male and female sexual stages of the parasites, called gametocytes, would make their way up the proboscis and into the female mosquito’s gut, where they would unite sexually and make a tiny sac in the lining of the insect’s stomach.
    Over a period of