The use of Opalina sudafricana in a biological test for diagnosing disordered metabolism of tryptophan in human subjects

Injections of urine of patients with bladder cancer linked with bilharziasis, simple urinary bilharziasis, ascariasis or ancylostomiasis, induced cyst formation found in Opalina sudafricana when injected into its host Bufo regularis. It is suggested that the carcinogenic tryptophan metabolites present in the injected urine reach the parasites in the recta of the experimental toads and stimulate them to divide mitotically to form small forms which eventually encyst. This test may be of a diagnostic help in detecting any abnormality in tryptophan metabolism in some human patients.