Infections of Moniezia expansa (Rudolphi, 1810) in sheep during the wet and dry seasons on St. Croix, US Virgin Islands

The sheep tapeworm, Moniezia expansa, occurred in 100% of lambs and wethers during the wet warm season (15 Jun-15 Dec) on the U.S. Virgin Island of St. Croix in 1999. In total, 924 mm of precipitation was measured during this period. In the early dry season and mid-dry season, the percentage of lambs and wethers infected was 25 and 44%, respectively. In total, 424 mm of rainfall was measured during this period (16 Dec 1999-15 Jun 2000). During the transition from wet to dry seasons, prevalence was lower in ewes (peaking at 29.6%) than in offspring. In lambs and wethers, prevalence increased to 58% and then declined to 44.4%. Temperature averaged 25 degrees C during the wet season and 29.4 degrees C during the dry season. Eggs per gram of feces (EPG), determined by the modified McMaster method, followed a similar pattern, peaking at 1,698 EPG in the wet season, 2,008 EPG in the early dry season, and 939 EPG in the mid-dry season. Infections were heavier and of greater duration in the wet season. The study started in September 1999 and ended in August 2000.