Effect of nitroxynil (fasciolid) on adult Fasciola gigantica and Fasciola hepatica in infected cows

Abstract

Background Drug resistance to treatment of fascioliasis with triclabendazole (TCBZ) has emerged in Sohag Governorate, Egypt. Nitroxynil belongs to the halogenated phenol group of fasciolicides. It is highly active against adult liver flukes. A nitroxynil metabolite is produced in the liver parenchyma adding to its flukicidal activity and augmenting its efficacy against late immature flukes that migrate through the liver tissues. Treatment with nitroxynil may be an effective replacement for therapy with TCBZ in cases of resistance. Objective The aim of this study was to evaluate the efficacy of nitroxynil in the treatment of fascioliasis by assessing its effect on teguments and durability of adult Fasciola gigantica and Fasciola hepatica worms. Materials and methods Infected cows were selected on the basis of clinical signs, and infection was confirmed by detection of Fasciola eggs in their stools. Nitroxynil was administered as recommended in two doses 15 days apart, and the animals were slaughtered 15 days after treatment. Fasciola worms collected from the bile ducts were identified and prepared for electron microscopy. Tegument changes were examined with scanning electron microscopy. Results The removed adult flukes of both species were moving sluggishly and appeared pale with no evidence of gut content. Scanning electron microscopy examination of these flukes revealed evidence of swelling of the tegument that showed regional variation in its severity. Loss of spines was also observed. Conclusion The present study demonstrated the flukicidal properties of nitroxynil, proving that the tegument is an important target for its action. Disruption of the fluke's main line of defense allowed the drug access to other internal tissues, leading to more widespread damage. Nitroxynil may be successfully used for treatment in case of resistance to TCBZ.