The Malaria Capers: More Tales of Parasites and People, Research and Reality
Some years ago I listened to an emotional appeal by a director of the World Health Organization to fight against the parasitic infections that kill millions of children in the Poor World every year. His speech fell flat, partly because the audience regarded it as a well-rehearsed and often repeated performance, and partly because mere numbers fail to arouse people’s emotions. By contrast, the opening of Desowitz’s book on tropical diseases strikes to the heart with the story of the illness and unnecessary death of a single child in India. Unnecessary, because the mother could have saved her child had she or the Indian government been able to afford $15 worth of medicine.
The disease was a parasitic infection known as kala azar. Desowitz’s book tells the story of the search for the organism that causes it and the way that organism is transmitted from patient to patient. Its heroes are the physicians of the British Indian Medical Services, many of them amateurs in science who, beginning in the late nineteenth century, pursued their research as a hobby with primitive means and often with more devotion than competence. They had many patients with the symptoms of the disease—enlarged spleen and liver, irregular fever, and anemia, among them—but could not find out what caused it. The first clue came at the turn of the century when Dr. William Leishman in London found microscopic egg-shaped bodies in the spleen of a soldier who had died from kala azar; later Charles Donovan in Madras found the same bodies in the spleen of a live patient and recognized them as protozoa, single-celled organisms a little larger and more complex than bacteria. They were aptly named Leishmania donovani.
How were they transmitted from patient to patient? First suspicions fell on the ubiquitous bedbugs. Dr. W.S. Patton in Madras spent five years patiently encouraging bedbugs to feed on his kala azar patients, hoping that the bedbugs would suck up the parasites, and was encouraged when he found some in their intestine. Later Mrs. Helen Adie, a researcher in Calcutta, claimed enthusiastically that she had actually seen them in the bedbugs’ salivary glands. Her findings were hailed as a breakthrough until others proved that she had looked at the wrong protozoa. People continued to probe in the dark until one man had a bright idea. This was Major John Stinton, the only man known to hold both the Victoria Cross for his bravery in battle and the fellowship of the Royal Society for his scientific achievements. Stinton took a map of India and compared the incidence of parasitic diseases with the distribution of various biting insects. His map showed a coincidence between the prevalence of kala azar and that of a tiny silvery sandfly, Phlebotomus argentipes.
Stinton published his findings in 1925, but it took another seventeen years until he was proved right. In 1923 a kala azar commission had been set up in Assam under the English parasitologist Henry Edward …
The Mystery of Malaria: An Exchange June 25, 1992