Problems in the Cultivation of some Parasitic Protozoa

Publisher Summary Trypanosomiasis of animals is a disease of great economic importance in Africa because it makes animal husbandry impossible in enormous tracts of country where the population is chronically deficient in protein, and although trypanosomiasis of man in that continent has been largely reduced by the control of the insect vector and by the use of prophylactic drugs, outbreaks still occur. Little is known of the mechanisms by which trypanocidal drugs produce their inhibitory effects upon the parasite and, with the exception of proguanil and pyrimethamine, which have been shown to interfere at different levels with folic acid metabolism in the malaria parasite, the mode of action of antimalarial drugs is not understood. Drug resistance also occurs in malaria parasites and the development, in South America and South-East Asia, of resistance to chloroquine, a drug used extensively in prophylaxis and treatment of the disease, has focused attention upon this problem. As yet, little is known of the changes occurring in trypanosomes when they become resistant to trypanocidal drugs and nothing is known of the changes associated with drug resistance in malaria parasites. For the solution of problems, whether they be mechanisms of drug action, the development of drug resistance, or the transformation of one morphological type into another with the accompanying physiological changes associated with change of host, a greater knowledge of the physiology and biochemistry of these organisms is necessary, and for this, methods of cultivation of all the stages of the life cycle are essential.