Death in the Valley

In the Peruvian Andes, not far from Lima, lies a haunted valley. To be caught there after dark, natives say, means almost certain death. If late afternoon finds a muleteer in the valley, he gets panicky and whips his beasts to escape lefore sunset. Workers on the Central Railway, which winds between the valley's forbidding mountain walls, insist on being taken home each night. Travelers through the valley dread to ride the railroad in the rainy season, for fear a landslide may maroon their train.

The horror that haunts this valley is a disease called verruga (literal translation: warts). It is transmitted by an almost invisible sandfly (Phlebotomus verrucarum), smaller than a mosquito, which bites only at night. Penetrating the finest netting and seams in clothing, the insect infects its victim with a parasite (Bartonella bacilliformis) that destroys red blood cells, produces a high fever and often kills within a few days.

Scientists first heard of verruga in 1870, during the building of the Central Railway, when 7,000 workers died before the rails had been pushed out of the valley. The first investigator of the disease was a medical student named Daniel A. Carrion, now a Peruvian national hero, who died after inoculating himself with serum from a patient's wart. Verruga is still something of a medical mystery. Nobody has ever found out how the sandfly acquires its parasite, where it lays its eggs, why it seems to have thrived only in one narrow area. Doctors have found no effective treatment for verruga. Natives burn animal dung and pungent eucalyptus leaves in their huts to keep out the sandfly. They also dose themselves with red wine and water in which corn silk has been boiled. Neither measure does much good. The natives appear to survive mainly because those who live through a mild form of verruga in childhood develop immunity.

Last week a verruga expert, Dr. T. S. Battistini of the Peruvian Hygienic Institute, thought he had a promising lead: the sandfly is extremely vulnerable to DDT. When the rainy season ends in June, Peru will launch an intensive DDT attack in a test area. It will be none too soon; verruga, long unknown outside of Peru, seems to be spreading. Since 1939 outbreaks have been reported in Colombia and Ecuador.

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