The Age of Plagues

It wasn't that long ago that medicine declared a victory over infectious disease. Now a raft of new and mutating bugs are at the door, and a declining public health system is in no shape to fight them.

Foodborne illness has always been a staple of epidemiologists' work, and it used to be relatively simple. Contamination was generally traceable to a particular dish, person, or event--"Grandma's potato salad at the church picnic," as Osterholm likes to put it. Now, chances are that the potato salad came from a deli, which shipped it in from a commercial kitchen. The spuds may be from Idaho, the green onions from Mexico, the mayonnaise from Kansas, and the parsley from Costa Rica. A bug may have hitched a ride on any of them, transferred from soil or water or the mostly impoverished people who harvested, packed, and chopped the food. "Around our department we have a saying," Osterholm cheerfully tells an audience whose forks have stopped clicking. "If you can't grow it in the lab, put it in the salad bar."

As infections go, foodbornes aren't the worst you could have. Most of the time, they resolve themselves after a few days of purging from every orifice (though in people with weak immune systems the results can be more devastating). But what they generally lack in deadliness they make up in frequency. Between 1979 and 1993, the Minnesota Department of Health confirmed 200 outbreaks of foodborne illness. Many more probably went undetected.

This story, with variations, plays out everywhere as bugs turn industrial technology to their advantage. Airborne microbes circulate over and over again in office buildings and airplanes. Cooling towers--along with shower heads, vegetable misters, and just about anything that stays dark and moist--can harbor legionella, the bug that causes Legionnaires' disease. And in 1993, 400,000 people got sick in Milwaukee after drinking tap water contaminated with cryptosporidium, a tiny parasite that causes diarrhea and can kill people with compromised immune systems. Elsewhere, tap water has been found to cause outbreaks of shigella, gaillardia, and hepatitis A.

Bigger parasites--rats, mice, mosquitoes--also have held up surprisingly well. In 1994, the medical establishment got its second major wakeup call when four previously healthy young people dropped dead in the Four Corners area of New Mexico. Their disease was eventually identified as being caused by hantavirus, a rodent-borne bug that has since been found to be common in mice and rats from coast to coast; there's now speculation that hanta infection from rodent-infested housing is one of the factors in the high incidence of kidney failure among African Americans. Similarly, over the last 10 years the United States has seen a gradual spread in the populations of two kinds of mosquitoes--Aedes aegypti and Aedes albopictus, the latter also known as the tiger mosquito--that can carry yellow fever and dengue. Dengue's most serious manifestation can lead to death by internal bleeding; outbreaks have been spotted in Central America and the border states, and many scientists consider it a good candidate for the next American epidemic.

The list goes on. Respiratory and middle-ear infections now break out in daycare centers with such frequency that "you open the refrigerator, and half of it is food, half is antibiotics," Osterholm notes. Malaria, once common in the U.S., is making a return in the South and Southwest. A case of Lassa hemorrhagic fever popped up in a Chicago suburb in 1989. And that's not to mention diseases you wouldn't think of as infections. A growing number of liver and cervical cancers are now considered to be caused by viruses. Sexually transmitted diseases are thought to be the major cause of infertility. Chronic fatigue, according to some researchers, may be an old, but reemerging infection.

"These are not the kinds of things that get solved with one outbreak investigation," Osterholm concludes to a room where you can now hear a pin drop. "These are long-term, forever kinds of problems."

In January 1992, a man walked into a south Minneapolis bar. It may have been any day of the week; he spent most of his time in the place. For a few weeks he'd been sick--coughing, feeling feverish, having trouble breathing. He didn't have a home and hadn't been to see a doctor in a while. Perhaps he thought he had a cold. Perhaps he didn't care to wait in the emergency room for hours.

By the time the man did make it to the ER, he had lost more than 70 pounds. He couldn't walk without help and was coughing up blood; he had chills and felt nauseous much of the time. The doctors tested him for tuberculosis, got a positive, and put him on antibiotics. Eventually he recovered. Over the next few months, something like 41 people who had hung out with him in that bar tested positive for TB; the case was written up in the New England Journal of Medicine as the first bar-centered TB outbreak ever recorded.

TB is one of those diseases that was thought pretty well conquered two decades ago. Sanitariums, to which "consumption" patients had been sent to breathe fresh air and stay away from other people, were closed; antibiotics could take care of the problem more cheaply and comfortably. But as early as the 1970s, some doctors in New York noticed that TB was returning, especially among homeless men and drug users. The numbers rocketed through the 1980s as the city's shelters filled to overflowing; one person could cough on dozens of others all night long, and give them all the disease. People with AIDS, who were often also homeless, were especially vulnerable to the infection.

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