Search for the Night Biter

In Houston last week, helicopters swooped low over bayous to lay thick mists of insecticide, and fire engines raced from block to block to spray chemicals in vacant lots. Citizens lined up to receive free handouts of bug-killing Malathion, and even kids at play carried spray guns to squirt at anything that flew.

It was all part of the city's sudden war on mosquitoes, sparked by a dangerous and spreading epidemic of St. Louis encephalitis, or SLE, which is more commonly known as sleeping sickness. In the past eight weeks nearly 400 Houstonians have been hospitalized and 19 have died. Nor was the worst necessarily past, for encephalitis sieges usually last about 16 weeks.

Houston's outbreak--the first in the city's history--began in the dingy Negro sections, where mosquitoes breed in open drainage ditches and get into houses through tattered window screens. But the disease quickly spread to all areas of the city, probably borne by the female Culex quinquefasciatus mosquito, a night biter that acquires the virus from birds (and possibly small animals and reptiles), which are thought by most experts to be the natural reservoirs of the disease. SLE attacks the spinal cord and the brain, destroying nerve cells and frequently damaging the small blood vessels that supply the brain.

For most healthy people, the disease is usually marked by nothing more than a bad headache and moderate fever. But in some victims, especially the very old and the very young, it has devastating effects: headache, stiff neck, high fever and vomiting. Some patients have convulsions and lapse into coma; a few of the survivors suffer crippling brain damage. On the average, SLE kills 10% of those it strikes. Despite more than 30 years of research, no satisfactory vaccine has yet been developed to immunize humans.

To help cope with Houston's problem, teams of expert researchers were rushed in from the U.S. Public Health Service's Communicable Disease Center in Atlanta. Some of them immediately went into the countryside to trap birds, rabbits and snakes in the hope of pinning down the source of the outbreak. As they got to work, word arrived of an apparent outbreak of a more virulent form of the disease in five West Texas towns, where some 50 were ill.

* So called because it was first recognized as a distinct virus-caused disease, different from the many other forms of viral encephalitis, in the 1933 epidemic that raged around St. Louis, when more than 1,130 people became ill and 201 died.

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