TRYPANOSOMA-SIMIAE - IN-VITRO STUDIES ON DRUG SUSCEPTIBILITY

Two Trypanosoma simiae stocks were initiated in culture with tsetse-de rived metacyclics. They were propagated axenically as trypomastigote f orms at 35-degrees-C in 4% CO2 in air. Populations of trypanosomes wer e incubated with various concentrations of antitrypanosomal compounds. Growth was monitored after 24 h of incubation and the growth inhibiti on was calculated. Diminazene aceturate, quinapyramine sulphate, DL-al pha-difluoromethylomithine, and Ro 15-0216 showed activity against the stocks. Suramin and Mel Cy showed little effect upon the growth of th e parasite populations. Isometamidium chloride gave questionable resul ts in the 24 h growth inhibition test, but the results of a long-term viability assay indicated some degree of drug resistance (or drug tole rance). The results obtained herein correlate with observations obtain ed from in vivo studies in pigs. It is thus concluded that in many cas es the cryptic nature of T. simiae rather than drug resistance is resp onsible for the failure of chemotherapy of simiaetrypanosomiasis in pi gs.