Field trial of the efficacy of praziquantel for the treatment of monieziosis in naturally infected sheep

Abstract

The purpose of the study was to evaluate the efficacy of praziquantel at 3.75 mg/kg b.w. and 5 mg/kg b.w. in treating Moniezia expansa and to observe the appearance of the parasite in the faeces of sheep following the treatment. Thirty-six sheep (24 male + 12 female), naturally infected with Moniezia expansa, were allocated to three groups according to the following dosage regimes: Group 1-3.75 mg/kg b.w., n = 12; Group 2-5 mg/kg b.w., n = 12; Control group, n = 12. The sheep were around 6-7 months old and weighed between 17.7 - 35 kg. Sheep were randomly divided into equal groups based on mean weight and sex. Faeces were collected after 12, 36, 60, 84, 108, 132 and 156 hours and just before slaughter (final 24 hours faeces) into faecal collection bags in the treatment groups. The collected faeces were then examined macroscopically for any parasite segments and microscopically for parasite eggs. After treatment the sheep excreted parasite segments as either normal parasite forms or deformed forms (melted and capsule or rosary forms). Equal numbers of animals (3 from each group) were slaughtered 10, 11, 12 and 13 days following treatment and their intestinal contents examined for the presence of parasites. None of the treated animals either in group 1 or group 2 had strobilae or scolices of M. expansa in their intestine contents after the slaughter. In contrast, sheep in the control group had 0.5-61 ml strobilae and 1-8 scolices belonging to M. expansa, Thysaniezia giardi and Stilesia globipunctata. It was concluded that praziquantel at the dose rates used in the study was 100 % effective against Moniezia expansa.