Strategic control of Dicrocoelium dendriticum (Digenea) egg excretion by naturally infected sheep

Abstract

ABSTRACT:The aim of this study was to determine the most appropriate months for applying albendazole (ABZ; oral suspension dose 20 mg/kg body weight) to sheep naturally infected with Dicrocoelium dendriticum and kept at pasture, in order to reduce parasite egg shedding to a minimum, mainly during the cold months and, as a result, decrease pasture contamination by viable eggs. Five animal groups (G), homogeneous as regards the number of eggs per gram (EPG) in faeces, were established. The treatment months were: G1, November and January; G2, November and February; G3, November and April; G4, January; and G5 (control), April. Ten samplings (S1-S10) were carried out every 35 to 45 days to collect faecal samples from the rectum of each animal in the five groups. The sedimentation technique and McMaster egg counting chambers were used to analyze the faecal samples. Due to the effect of albendazole (ABZ) treatments, the five groups behaved differently with regard to EPG reduction and the percentage of samples positive for D. dendriticum eggs. Using the Kruskal-Wallis test, statistically significant differences (P < 0.05) were observed between the EPG values obtained in G5 and the rest of the groups from November to May, but not from May onwards. The biggest reduction in egg excretion was obtained in G1, mainly in the cold period when elimination is highest and egg survival greatest, so G1 gave the best result, followed by G2, G4, G3 and finally G5 in descending order.

Chronic Wasting Due to Liver and Rumen Flukes in Sheep

“…However, that method will work on small pastures only. As combating the intermediate hosts is not a reliable prophylactic strategy, an effective drug treatment of livestock is the most useful control method of dicrocoeliosis [ 78 ].…”

Detection of Dicrocoelium dendriticum larval stages in mollusc and ant intermediate hosts by PCR, using mitochondrial and ribosomal internal transcribed spacer (ITS-2) sequences

“…The economic and health importance of dicroceliosis is mainly due to direct losses caused by liver condemnation and indirect losses due to hepatobiliary alterations produced by the parasites and the costs associated with anthelminthic treatments, unsatisfactory until now (Otranto and Traversa, 2002; Manga-González et al . 2004, 2010). The life cycle of D. dendriticum is extremely complex because land molluscs and ants are required as first and second intermediate hosts, respectively.…”

“…Nevertheless, to apply successful strategic control programmes against dicroceliosis, prior study of its epidemiology is needed (Manga-González et al . 2010). This requires carrying out specific and early diagnosis using extremely reliable techniques to detect the presence of D. dendriticum in its definitive hosts (mammals) as well as in its first (molluscs) and second (ants) hosts.…”

Thermodynamics of egg production, development and hatching in trematodes

“…Egg production under experimental cold conditions is more poorly understood, although in homeothermic hosts, such as mice, cold stress appears to have no negative effects (Ichii et al , 1990). Under natural conditions homeotherms may optimize egg productivity during the winter if summer conditions are too harsh (Gonzalez-Lanza et al , 1989; Manga-González et al , 2010), whereas in trematodes within heterothermic hosts egg production tends to slow down when hibernation is induced (Morley & Lewis, 2014). Data on the effects of cold stress on egg production in ectothermic hosts are scarce, but remain more obviously negative due to the resulting drop in host feeding and associated nutrient availability, ensuring a decline in adult worm metabolism (Chubb, 1979; Mills, 1980).…”