Itching to Study Lice and Mites

In 1939, when World War II broke out, I held the Royal Society's Sorby Research Fellowship and was working on problems of insect physiology at Sheffield University. As my name was on the Central Register of Reserved Occupations, I was debarred from military service so as to be available for scientific work of national importance. Unfortunately, the authorities had no suggestions for any such work. I felt I should temporarily abandon insect physiology and devote my talents to some problem more closely connected with the war effort. The obvious field for such work seemed to be human parasitology, for in previous work at the London School of Hygiene and Tropical Medicine I had made ecological and physiological studies of lice, fleas, bedbugs and other insects of medical importance. From the various public health and military authorities I approached I received little encouragement and no practical suggestions as to problems they would like me to attack. It was evident that any initiative would have to come from me. During World War I, human lice, carriers of typhus and trench fever, had caused millions of deaths among soldiers and civilians, and it seemed likely that this situation might be repeated. Already there was considerable worry about head lice, which had been found on a high proportion of city children evacuated to the country to avoid the expected air raids. This surprised public health authorities, for statistics based on regular medical inspections had detected only a tiny proportion of verminous children, even in slum schools. I eventually persuaded the national Board of Education (then governing state schools and their medical service) to let me investigate the problem. I found that the published statistics were grossly inaccurate, for in several cities more than half of all teenage girls harbored infestations of Pediculus humanis cap itis, the head louse. This finding helped to stimulate an intensified program of louse control. My work on lice brought me into contact with many physicians, particularly those treating children. Time and again I was told that one of their major worries was scabies, or “the itch,” an irritating disease caused when the mite Sarcoptes scabiei burrows into the epidermis. The disease was common and difficult to cure. The general belief was that it was caught from dirty bedding used by infected individuals. There was concern that in the chaos resulting from air raids, which were expected to start soon, the disease would spread like wildfire in crowded underground air raid shelters, particularly if heat sterilization of bedding and clothing were impossible. This was obviously an important practical problem that no one was tackling. I therefore sought to study how to prevent or at least minimize transmission. I proposed to recruit volunteers who would expose themselves to infected bedding, particularly to discover how long the parasites would remain viable without heat sterilization. To my surprise, in view of the little encouragement I had received, the Ministry of Health gave me a small grant and permission to do the work. So I recruited a dozen young men, all conscientious objectors to military combat who were willing to expose themselves to infection for humanitarian reasons. Incidentally, I can record that during several years they all gave excellent service and proved most cooperative, even when subjected to painful and excessively tedious experiences.. I also rented a large house and furnished it as a research hostel cum laboratory, using many items acquired at auction. The army agreed to supply bedding used by scabies patients. I planned to store this for different periods, expecting its infectivity to decrease with time. The results were most unexpected, however. After six months’ exposure, none of my volunteers was infected with scabies. They did not catch the disease even when they rushed ked between blankets still warm from the body of a patient. We had thus shown that bedding was not important in transmitting scabies. The medical profession eventually was convinced, and the routine sterilization of blankets was stopped. This saved the authorities some thousand times the modest research expense. When hundreds of thousands of people later occupied air raid shelters, there was no increase in the incidence of scabies. We had now completed the research program originally proposed, and in a properly organized institution our work would have ended. Fortunately it did not, for in the next two years we made many other discoveries of a kind we could not have foretold. I initiated a parasitological study of the itch mite, believing that this should lead to progress in treatment and prevention. By this time I had learned how to infect my volunteers by digging live mites out of patients and transferring them to my victims. I also found that the mites were transmitted by close personal contact. Infection was often venereal with soldiers, but also occurred in children who shared beds. We learned that scabies has an "incubation period” of about six weeks," during which no symptoms can be observed. This was important; previously, symptoms were expected within days of picking up a parasite, so the wrong source often was blamed. There were other findings of medical importance, including the way in which patients become sensitized and start to itch, and how reinfection may be more difficult than the initial infection of previously unexposed individuals, since some degree of "immunity" may develop. From the scientific point of view we learned a great deal about parasites, their population and behavior. Perhaps our most important finding concerned treatment. At that time many patients were being continually treated for weeks or months, and apparently still were not cured some children missed school for years because they were thought to be infec- tious. By studying the effects of various me- dicaments on the parasites we soon found that treatment was much simpler and more effective than generally accepted. One thorough application of benzyl benzoate to the body surface usually killed the parasites and cured the patient. Unfortunately, though the prime cause was removed, all the symptoms were not. Itching often persisted; as a result, the treatment was repeated. Most medicaments are irritating to the skin, so the disease was thought to be getting worse. As a result of our work, patients were-given only one treatment, which cured 99 percent of the cases, even though soothing ointments were still required for the itching. This improvement in treatment released the equivalent of two divisions from military hospitals, as well as affecting even larger numbers of children and civilian workers. My pacifist volunteers were gluttons for punishment. They were anxious to take part in as many useful experiments as possible, and did not find suffering from scabies to satisfy their consciences. So, in conjunction with the Medical Research Council, we organized long-term experiments to determine the minimum requirements for vitamin A and vitamin C. This work, which was possible only because of the organization built up for the scabies study, resulted in two Medical Research Council special reports. The lesson is simple. Ideas for practical research are more likely to come from active young scientists than from learned councils and committees. We need to find ways of encouraging such work and of interfering with its progress as little as possible. I was lucky; there was a war on, and the red tape that strangles so much initiative could be cut in a way that would be more difficult today. Mellanby an entomologist and ecologist, was founding principal of the University of Ibadan in Nigeria and the first director of Monks Wood Experimental Station for ecological research in Britain.

Itching to Study Lice and Mites

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