Fluorescence of Tetracyclines in Filarial Worms. ∗

Summary

1. After administration of tetracycline to a patient having migrating, subcutaneous filarial worms, parasites were localized and visualized as yellow-fluorescent tracts beneath the skin following stimulation with UV light. 2. Exposure of microfilariae of D. immitis in vitro to a solution of chlortetracycline resulted in uptake of antibiotic by embryos in amounts which were readily visible by fluorescent methods. 3. In vivo studies on a dog infected with D. immitis revealed that the central column of nuclei of each microfilaria specifically took up tetracycline. The drug also was deposited in adult worms making them brilliantly fluorescent. In fresh-frozen sections of an adult female worm, the drug was localized throughout internal structures including uterus with its contained embryos.