Outbreak! Plagues That Changed History by Bryn Barnard Read Free Book Online Page B

Condition of the Laboring Population of New York.
Jacob Riis’s 1890 blockbuster,
How the Other Half Lives,
also helped ignite American reform. Across Europe and America, and later Japan and other parts of the industrializing world, cities were transformed from fetid sties to livable metropolises with improved housing, efficient sewers, clean piped water, and regular garbage removal.
    To understand the importance of these changes, one has only to look at the fate of an industrial nation denied the basics of modern life. Iraq is an instructive example. Though the dictator Saddam Hussein ruled Iraq for much of the late twentieth century, the country was modern and prosperous, with a large, educated middle class concentrated in cities like Baghdad, Fallujah, and Basra. In the 1990s, however, the United Nations implemented sanctions that denied Iraq critical water treatment system parts and medicalsupplies the Iraqi government might have also been able to use to manufacture weapons. The health effects were immediate, widespread, and ghastly. Infant mortality rose sharply. Infectious diseases spread. Cholera returned. In all, about a million Iraqi children died. Any other industrial country denied essential modern sanitation would suffer a similar outcome.

Have vibrio, will travel
    Thirty years, two cholera pandemics, and hundreds of thousands of deaths after John Snow’s observations, the great German biologist Robert Koch finally discovered the microbe responsible for cholera. In 1883, during the fifth pandemic (1881–86), Koch beat his archrival, Louis Pasteur, by identifying the cholera vibrio in the disease’s homeland, India. Koch became a German national hero. (
Vibrio
is one of the many shape-based words still used to describe bacteria. A vibrio is comma-shaped. A bacillus is rod-shaped. A spirochete is screw-shaped. A coccus is round.)

     
    The bacterium
Vibrio cholerae
     
    In Koch’s day, cholera’s life cycle was a mystery. Today we know that vibrios adhere to the lining of the small intestine, where they multiply and excrete a toxin that prevents intestinal cells from efficiently absorbing water and causes the body to lose water and salt into the intestines. Cholera diarrhea can range from mild to deadly. In extreme cases the host is so dehydrated that blood thickens to a tarlike consistency and the skin is tinted the telltale blue. Blood pressure plummets, and the host dies.
    We now understand that cholera vibrios can survive for years in a sporelike state on the bodies of copepods, millimeter-sized crustaceans that feed on algae. At one time this trio of organisms—vibrios, copepods, and algae—coexisted mostly in the Bay of Bengal. When water temperatures rose and enough nutrients were available, algae would bloom, and copepod and vibrio populations grew. If a tropical cyclone, tsunami, or other event caused this cholera-rich seawater to contaminate inland drinking-water supplies, cholera could reenter the human infection chain. But today ships have sucked up Bay of Bengal ballast water and spewed it out around the world, introducing the bacteria to other areas. Three different strains of the cholera vibrio now compete for dominance. The Classic strain is deadly but susceptible to disinfectants such as chlorine. It is now rarely encountered. The newer El Tor strain causes a milder illness but is more resistant to chlorine. It is now the most common strain by far. The hybrid Bengal strain is both deadly and resistant.

So cheap yet so far
    Cholera remains a formidable illness. It would girdle the earth in a sixth pandemic that lasted from 1899 to 1909. A seventh—not yet over—began in 1961 in Indonesia. Unlike the cholera of Chadwick’s day, however, the disease is now a preventable, curable illness. We can treat and filter water to make it safe to drink. We can rehydrate cholera victims with water mixed with special salts and sugars. Nearly everyone so treated survives. Cholera should be history.