Photochemotherapeutic method using 5-aminolevulinic acid and other precursors of endogenous porphyrins

Methods of detecting and treating rapidly growing exogenous cells, such as Protista, or parasites, that preferentially accumulate a photoactivatable porphyrin in which 5-aminolevulinic acid or precursor thereof is administered to the patient, or contacted to the exogenous cells, in an amount sufficient to induce synthesis fluorescence and/or photosensitizing concentrations of a protoporphyrin IX in the exogenous cells, followed by exposure of the exogenous cells to light of photoactivating wavelengths.