Anti-Inflammatory Effects of Tartar Emetic and Niridazole: Suppression of Schistosome Egg Granuloma

Abstract

Treatment of cerebral schistosomiasis japonica with tartar emetic produces a remarkable and rapid improvement which cannot be explained on the basis of worm destruction alone. In dracunculiasis, niridazole appears to have an anti-inflammatory effect facilitating the extraction of the adult worms. In addition to their antischistosome effects these drugs may serve to suppress the response to schistosome eggs which has been demonstrated to be a form of delayed hypersensitivity. Niridazole and tartar emetic were administered, in their recommended therapeutic doses, to mice. In unsensitized animals granulomas appeared by the 4th day and reached their peak at 16 days. Treatment with the drugs resulted in no reaction at 4 days, minimal reaction at 8 days, and marked suppression at 16 days. Mice sensitized by the prior injection of eggs developed large reactions 1 day after intravenous egg injection and massive reactions by 8 days. No reaction was seen at 24 hr in the treated animals and, at 8 days, the reactions were 50% smaller than in the controls. In egg-sensitized mice both drugs suppressed delayed footpad swelling to soluble egg antigens, another parameter of delayed hypersensitivity. The degree of inhibition of granuloma formation by niridazole and tartar emetic was similar to that of many of the major immunosuppressive drugs, neonatal thymectomy and antimacrophage serum. The rapid amelioration of cerebral schistosomiasis, the ease of guinea worm extraction, and some of the other effects of these drugs, may be explained by these observations.