New Plagues for Old?

Mystery maladies keep disease detectives busy

The list of deadly but controllable diseases is long and impressive: plague, diphtheria, malaria, polio, smallpox, typhoid and yellow fever. Even cancer and heart disease at last seem to be yielding up their secrets to medical research. But in the past ten years, doctors have focused on a number of mysterious "new" ailments, notably Legionnaires' disease and toxic shock syndrome.

One reason for the flurry of strange ailments is that diagnosis constantly becomes more refined. Dramatic advances in laboratory technology, like the use of radioactive substances, have helped doctors better understand disease processes. Also, physicians are more alert in reporting both established and unusual illnesses to their colleagues. Some apparently new diseases existed in the past, notes Epidemiologist Michael Gregg of the Center for Disease Control in Atlanta, the nation's primary illness-monitoring station. But Gregg adds, "There may also be an essentially evolutionary environmental change. Something that is going to bring the host, the agent and the environment together in a different way from before, creating a new ailment."

Some of the mysterious new maladies are limited to specific geographic areas. Some have thus far attacked very few victims. Among the ailments intriguing disease detectives:

Hemorrhagic Fevers. A deadly collection of virus-caused illnesses, they have so far been found mostly in Africa and other tropical regions. Patients run high temperatures for several days, then hemorrhage from the nose, mouth and intestine. Depending on the particular type of hemorrhagic fever, up to 90% of victims die. Last year such fevers claimed more than a thousand lives. The viruses live in animals apparently without causing any symptoms, then are passed to human beings. In Lassa fever, the organism lives in a particular type of rat that infests rural dwellings in West Africa. It spreads to villagers through water or food contaminated by the rodents' urine. In Marburg and Ebola fever, the animal host is still unknown. What makes these diseases particularly grim is that they can be spread person to person, often to nurses and doctors, through infected blood.

Reye Syndrome. This malady primarily attacks children between the ages of five and eleven. No cause has been identified, but the syndrome has been linked to viral illness, commonly striking its young victims as they recover from chicken pox or influenza. The symptoms, described by Australian Pathologist R.D.K. Reye in 1963, are severe vomiting, followed by lethargy and later by personality changes, convulsions, coma and even death. The syndrome is rare. Last year fewer than 600 cases occurred in the U.S., mostly during the flu months of January, February and March. Both the public and physicians are becoming more familiar with the illness, and children are now hospitalized earlier for the intensive care they need to survive. Even so, 25% of children who develop the syndrome die.

Lyme Disease. In 1975 Yale researchers began investigating a highly unusual cluster of arthritis cases among families living in the rural area of Lyme, Conn. Later, doctors at the U.S. submarine base in nearby New London reported several patients with a distinctive skin lesion that in Europe had been associated with tick bites. The seemingly unrelated ailments became linked when the Yale research team found that about a quarter of Lyme arthritis victims had also had the skin lesions a few weeks before their painful joint swellings began. Subsequent investigations revealed that the skin lesions, arthritis and many other ailments, including encephalitis, meningitis, paralysis of the face, arms and legs, and heart abnormalities, could be traced to bites from a species of tick (Ixodes dammini) that infests the area. Just what disease-causing agent the tick transmits is still a puzzle.

The complex of illnesses is not limited to Connecticut. Ixodes dammini is found along the East Coast from Massachusetts to Maryland, as well as in Wisconsin. A related species lives in California and Oregon. Lyme disease has occurred in all these areas.

Infant Botulism. Botulism usually comes from eating improperly canned food contaminated by toxin produced by the bacterium Clostridium botulinum. Four years ago, researchers at the California health department found that babies with no obvious exposure to such canned foods were coming down with the disease. C. botulinum bacteria are ubiquitous. They thrive in the earth and are spread as spores through dust in the air as well as on vegetables, fruits or in honey. Adults regularly ingest the microbes but customarily suffer no harm. The spores remain dormant in the adult intestine. For as yet unknown reasons, the intestines of some babies aged one to six months provide a hospitable environment for the spores, permitting them to germinate and make their deadly toxin. It is a nerve poison that produces an array of symptoms including constipation, lethargy, poor feeding, weak crying and general floppiness. More than 170 cases of infant botulism have been officially reported worldwide since 1976, but the count is probably far too low. Many physicians are still unfamiliar with the illness, and no simple diagnostic test exists. Evidence suggests that infant botulism accounts for at least 5% of the more than 8,000 cases of sudden infant death that occur yearly in the U.S. alone.

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