KILLING PARASITES BY DRUGS 37 



the disease. The result was the discovery by Colonel 

 Bruce of the parasite of sleeping sickness called Try- 

 panosoma a kind previously known in some other 

 diseases and of the fact that it is a tsetse-fly which 

 carries it. A quarter of a million natives have died 

 in Central Africa within the last six years from sleep- 

 ing sickness. The Tropical Diseases Committee of the 

 Royal Society has started an inquiry into the action of 

 drugs on the parasites (known as trypanosomes) which 

 cause sleeping sickness and the horse and cattle disease 

 of the " fly-belts" of South Africa. 



The minute parasites which cause Malta, yellow, and 

 malarial fever, and other infections, are no doubt best 

 dealt with by excluding them from access to the human 

 body when that is possible. But once they have 

 effected a lodgment and commenced to multiply in the 

 blood or tissues, it is still possible to get at them by 

 means of drugs, which poison them without injuring 

 their human victim. Thus quinine has been of 

 enormous service in checking the ravages of the malaria 

 parasite, and really in Great Britain has exterminated 

 "ague," which is the English name for malaria. 

 Many experiments have been made during the last two 

 years, with the view of finding some drug which will, 

 in like manner, destroy the trypanosomes which have 

 established themselves in the blood and lymph-passages 

 of the human body, and are slowly killing their victim 

 with sleeping sickness. An arsenic compound, " atoxyl," 

 has been found effective when injected into the patient's 

 body, and according to Dr. Koch, who returned last year 

 from Uganda, he has found nothing better than this 

 treatment, discovered by Dr. Thomas and Dr. Breinl, 

 of the Liverpool School of Tropical Medicine, three 

 years ago. Dr. Plimmer and Dr. Thomson, who 

 have been experimenting in London for the Royal 

 Society, have found a drug which is more effective than 

 atoxyl in destroying certain trypanosomes which attack 



