Filtering Out the Flukes

Surgery is not strictly a matter of cutting into patients and cutting something out. The A.M.A. last week heard about a new operation designed not to cut out but to filter out the tiny parasites that cause schistosomiasis, a disease that is rapidly displacing malaria as mankind's greatest scourge in tropical regions.

Schistosomiasis, or snail fever, afflicts about 200 million people, chiefly in Latin America, Africa and Asia. Caused by parasitic blood flukes, it is found around marshy deltas, sewage-contaminated lakes and irrigation ditches, where the larvae of the worms lodge in snails and flourish. Invading the human body through the skin, the larvae head for the liver, there mature into flukes that migrate to the small veins of the bowel, where the female lays innumerable eggs every day, sometimes for years. Many eggs are swept into the liver and other organs. They cause irritation and scarring in the liver (which leads to enlargement of the spleen), intestinal damage, bleeding from the esophagus, stunting of growth, anemia and blood in the urine. Though surgery to remove the spleen gives the patient some relief, it does not eliminate the flukes, which go right on laying eggs.

A Dose of Emetic. Now, Cornell University's Dr. B. H. Kean, a specialist in tropical medicine, and Surgeon Edward I. Goldsmith have devised a method to remove most of the flukes. The two reasoned that when a patient is cut open to have his spleen removed, he might as well be rid of the flukes at the same time. They designed a system of tubes to pipe the blood from the vein entering the patient's liver, pumping it through a filter, and returning it to a vein in the leg (see diagram). In order to lure the flukes out of their customary lairs in the intestinal veins, they give patients a single injection of tartar emetic. The flukes, which find the emetic as unpleasant as most human beings do, come scurrying out into the main bloodstream, and are shunted through the tubes. Since they are about half an inch long, they are stopped and trapped by the filter, while the blood passes through, unharmed.

Reporting to the A.M.A. on the results of the first 20 applications of the technique on schistosomiasis victims in Brazil, Dr. Kean said as many as 1,668 worms had been filtered from the blood of a single patient. The patients had been excreting thousands of eggs a day; after the operation, ten excreted no more eggs, suggesting that all the mated flukes had been filtered out of their systems, and seven others showed great improvement. Though it was developed specifically for the fluke Schistosoma mansoni, common in South America and Africa, Drs. Kean and Goldsmith believe the technique can be adapted to remove both the Asiatic form, which causes an even more severe disease, and a variety that is common in the Near East and exposes Africans to double jeopardy.

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