A case of sleeping sickness studied by precise enumerative methods: Regular periodical increase of the parasites disclosed

Abstract

Prefatory Note by R. Ross ―For a long time it has appeared to me that much light might be thrown on infectious diseases, immunity and treatment, by more exact enumeration of the infecting organisms, and that we might even be able ultimately to apply mathematical reasoning to the study of these subjects. In 1903 I elaborated a method of blood examination, called the thick-film process , which enables us to detect small organisms in the blood about twenty times more easily us to detect small organisms in the blood about twenty times more easily than in ordinary preparations; but for the lack of the necessary assistance I was long unable to apply the method to the laborious enumeration of such organisms. Recently Fund has placed considerable funds at the disposal of the Liverpool School of Tropical Medicine for the study of cases in the tropical ward of the Royal southern Hospital, Liverpool―with the result that the investigations referred to were commenced by Dr. David Thomson and myself from the beginning of this year. As I expected, methodical counting of the parasites has at once verified or disclosed several facts of importance in connection with malaria and trypanosomiasis. We now limit ourselves to a brief description of the remarkable periodical increase of Trypanosoma gambiense revealed by careful daily counting in a case in my clinic (the case, which is still under treatment, will be fully reported elsewhere). W. A., male, aged 26 years, a strong young man born in Northumberland, was infected in N. E. Rhodesia in September, 1909, the trypanosomes being found in his blood in Africa on November 17. On coming to Liverpool for treatment he was admitted into the Southern Hospital on December 4. From then until February 16 (73 days) the number of trypanosomes in his blood was estimated only by the rough methods in common use; that is, by the proportion of trypanosomes to red cells or leucocytes, or to “fields” of the microscope examined. These methods are obviously open to such great error that they can scarcely be depended upon to indicate any but very large differences in the numbers of objects counted. During the 73 days 46 counts were made; but on several occasions none was attempted for three or four days in succession―so that, even if the methods of counting employed had been more accurate, sudden fluctuations might easily have been missed. Hence, as was to be expected, the graph during this period is very irregular and almost worthless. On admission on December 4 the patient was reported to contain about 6000 trypanosomes per cubic millimetre, were found on December 17 and 28 and on January 16. All this time the patient was given the usual treatment with atoxyl and mercury, and received altogether 10 doses of two to four grains of the former. Nevertheless the parasites never fell below about 200 per cubic millimetre in number, as roughly estimated.