The efficiency of the oogram method for the primary screening of drugs in schistosomiasis has been assessed with known schistosomicides that included 7 antimonials, 8 xanthone derivatives, 2 p-aminophenoxyalkane derivatives, 2 emetine and 4 other compounds. The drugs were administered, for 5 consecutive days, to mice experimentally infected with Schistosoma mansoni, the daily dose being one-fifth to one-fourth of the LD50's. The animals were sacrificed 3 days after the end of treatment. All schistosomicides have been found to produce changes in the oogram (i.e., the relative proportions of eggs in progressive stages of development found in intestinal and liver fragments).
The study of the oogram from infected mice treated with decreasing doses of schistosomicides demonstrated that the oogram method is very reliable and extremely sensitive. Oogram changes occur even at dose levels that do not cause a massive shift of schistosomes toward the liver.
The usefulness of the oogram method for preclinical and clinical trials in schistosomiasis and its importance for the primary screening of potential schistosomicides are emphasized.
Address: Instituto de Biología, Faculdade de Filosofia, C. Postal 253, Belo Horizonte, Brazil.