1999. They are still with us. We are still getting cholera and the bubonic or pneumonic plague. In 1999, for instance, there were 35,600 new cases of syphilis and 17,500 people were diagnosed with tuberculosis; more than 1,600 cases of malaria were documented, up from the year before; 350 new cases of typhoid fever were reported, and more than 100 people came down with leprosy. That year, doctors notified the Centers for Disease Control of fewer than 10 cases each of plague and cholera — but these diseases were beginning to show up in some numbers toward the latter part of this 56-year period — having been virtually absent in the 1940s, 50s, and 60s.
The battle against disease is still going on. The climbing rates of some diseases, the persistence of others, and the reemergence of lethal ailments all illustrate that modern medicine has its limits. We also are aware that if we relax our vigilance — or if the social arrangements that keep disease at bay loosen — the plague can come back and consumption can once more waste us.
No exhaustive treatment of these diseases is possible in a single panel. We show these data to hint at possibly adverse social trends. We have touched briefly on sexually transmitted diseases. The presence of syphilis in the population, and its occasional flare-ups, illustrates the tenacity of the syphilis spirochete — a tubular bacterium that bores into broken skin or mucous membranes and causes havoc — the unruly form of our passions, and the limits of the antibiotics with which we combat this disease.
Tuberculosis — the ravages of which were mourned by Verdi in La Traviata, and by Puccini in La Bohéme — has been showing a resurgence (not well seen in this graphic). There are several likely causes for this resurgence, including increased HIV infection (which reduces immunity), homelessness, other forms of extreme poverty, poor nutrition, and the appearance of drug-resistant strains of the disease. Crowding and unsanitary habits and conditions contribute to TB's spread: coughing or sneezing spreads infected droplets. Most people recover — but some few still succumb to the disease. As strains of the tuberculosis bacterium become resistant, major efforts must be made to find new, still effective antibiotics. One hopes that an industry busy inventing new drugs — that reduce our obesity or prop up our potency — will keep up with the demand for drugs that are used predominantly by the lower socioeconomic classes.
The incidence of typhoid fever is still very high for a country with modern water treatment facilities and high levels of sanitation. The Salmonella typhi bacterium found in poorly treated water and spread from water to food and drink causes this disease. Typhoid is also exhibiting drug resistance. Complications of the disease (intestinal hemorrhage, intestinal perforation, kidney failure, and peritonitis, inflammation of the abdominal lining) can be fatal. A few people can carry the bacteria without being affected. The bacteria appear in their feces. The most famous of these unfortunates was Mary Mallon, a cook who worked in New York in the early part of the 20th century. Wherever she went, people came down with typhoid. Many died. This was Typhoid Mary. She spent many years of her life in quarantine. The continued presence of the disease is blamed on foreign travel.
Malaria also is a communicable disease associated with travel to the tropics. Malaria is a parasitic disease. Mosquitoes spread it. Mosquitoes pass the parasites (sporozoites) to people. The parasites, after many travels in the human body and long colonization of the liver, eventually return to the mosquitoes by way of human blood and have another career in the mosquitoes' stomachs and salivary glands — then it's time to immigrate again. It is interesting to see that peaks in the incidence of the disease appear at the time of World War II, the Korean War, and the Vietnam conflict. Increased travel to tropical regions causes the disease to claim more and more victims of late. Travelers can prevent the disease with certain drugs. Mefloquine, specific for the most dangerous type of malaria, falciparum, can cause confusion and other mental side effects — just the sort of things you need to experience as you take boat into Joseph Conrad's Heart of Darkness. Indeed, studying malaria — or the spirochetes of syphilis — one gets the idea that humankind's conquest of the earth has a ways to go yet.
Like typhoid fever, cholera reaches people by way of contaminated water. It causes diarrhea and kills by dehydration, which can occur very rapidly, unless counter-measures — rehydration, antibiotics — are taken. One type of cholera bacterium, Vibrio, is associated with shellfish, especially raw oysters. Of special note, in our graph, is the reappearance of cholera in 1991. Until then it was fairly sporadic — and in the period 1944-1964 no cases were reported at all. Suddenly, in 1992, we had more than a hundred cases. The cholera epidemic broke out in South America and spread to the United States. One cannot help but wonder if some kind of control is breaking down. In our eagerness to detect terrorists, inspections of contaminated seafood may be lapsing even more radically in the future. As it says in the musical, Hair, "Don't drink the water and don't breathe the air."
The plague, which some of us have thought was "history," is still going too. The word is not a generic for any or all kings of serious disease epidemics. There is a real plague. It comes in a bubonic and pneumonic variety. Bubonic plague gets its name from swollen lymph glands (buboes); pneumonic plague causes pneumonia. Half of all cases of bubonic and all cases of pneumonic plague lead to death if no treatment is provided. Antibiotics are used to treat these types of plague. Fluids are provided intravenously, oxygen and other forms of respiratory support are used. With treatment, 5% of all cases die — but during the outbreak in the 1980s, according to the Centers for Disease Control, one person in 7 died, which is 14%. This death rate suggests problems of detection and failure to report for treatment.
Lice living on rats pass the plague. The agent is the bacterium Yersinia pestis. Rat infestations suggest inadequate housing and pest control — children and adults living close enough to rats so that the lice can make the leap to humans and bite them. Thus the much higher prevalence of the plague in the latter part of the 56-year period shown in the graphic should give us pause. The incidence is still low, hovering around 10 cases a year.
Finally, we come to leprosy. The incidence of the disease peaked in 1985 with 361 new cases, corresponding to an influx of Indo-Chinese refugees reaching the U.S. in the 1978-88 period. Worldwide there were 640,000 new cases in 1999, 738,284 cases in 2000. The disease is growing worldwide possibly because the cause, Mycobacterium leprae, has been showing up in drug-resistant varieties. The disease damages nerves in the extremities. People lose sensation in their hands and feet and often, for that reason, injure themselves. Their muscles weaken. The mechanism of transmission is still not known with certainty but is thought to be through respiratory droplets. Thus close contact with those who have the disease is a risk factor.
In the next panel, we look at new diseases.
Source: Centers for Disease Control and Prevention. Summary of notifiable diseases, United States, 1999. MMWR 1999 and earlier years.
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