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Yomesan (2',5-dichloro-4'-nitrosalicylanilide) was used in experimental infections of chicks with Raillietina cesticillus to determine the prophylactic activity. Cestode numbers were markedly controlled in birds receiving the drug in the diet at or above 20 mg/kg/day. Tapeworms remaining in treated birds were stunted and did not pass mature proglottids in the feces. This suppressive action existed throughout Yomesan medication. Five and 10 days after drug withdrawal, 58 and 75% of retained cestodes developed to maturity. Hygromycin B appeared to be compatible with Yomesan. Recently, a new experimental taeniacide, Yomesan (registered U. S. Pat. Off. by Farbenfabriken Bayer A. G.), has been reported by Gonnert and Schraufstatter (1960) to be effective in the removal of Hymenolepis diminuta, Taenia hydatigena, Dipylidium caninum, Moniezia expansa, and Raillietina sp. established infections. According to the manufacturer, the taeniacidal activity is due to a direct disintegrating action on the tapeworm in the region of the neck. Strufe and Gonnert (1960) described the distribution of Yomesan in the alimentary tract of rats heavily infected with H. diminuta. Hecht and Gloxhuber (1960) demonstrated a low toxicity in rats, rabbits, dogs, and humans. Yomesan has shown little activity against Heterophyes infections in man (Nagaty and Khalil, 1961). Complete removal of Raillietina and Davainea species in fowl was reported by Kurelec and Rijavec (1961) with similar results in dogs experimentally infected with Echinococcus granulosus. According to Nagaty et al. (1962), anthelmintic action is lacking against infections with Ascaris, Ancylostoma, Enterobius, and Trichostrongylus. A significant percentage of cures after Yomesan treatment was shown in humans with Taenia saginata (Shafei et al., 1962). Tapeworm infections in sheep were significantly controlled by this drug with mild diarrhea occurring (Zettl, 1962). Contrary to the previous study of Kurelec and Rijavec, Forbes (1963) reported that Yomesan failed to control Echinococcus but completely removed T. hydatigena from dogs at 100 mg/kg of body weight. However, Delak et al. (1963) reported control of Echinococcus in 76% of treated dogs, following oral doses of 500 mg/kg. Toxocara canis, Received for publication 14 November 1963. An ylostoma caninum, and Trichuris vulpis were not affected by this dose level. Inasmuch as the effectiveness of Yomesan has not been investigated on a prophylactic basis against developing cestode infections, the authors tested the drug against experimental Raillietina cesticillus infections in chicks to note anthelmintic effects. MATERIALS AND METHODS The structural formula of Yomesan, 2',5-dichloro4'-nitrosalicylanilide, is as follows |
