Field and experimental studies onDicrocoelium dendriticumand dicrocoeliasis in northern Spain

Abstract

AbstractThe transmission, control and the relationship betweenDicrocoelium dendriticumand its definitive (sheep and cattle) and intermediate (molluscs and ants) hosts under natural and experimental conditions are described. Eleven species of molluscs and four of ants were found infected with larvalD. dendriticumin León province, north-west Spain. Infected ants were observed between April and November and in tetania at 7.5–26.9°C. The highest shedding of eggs by sheep and cattle was detected in winter. Two treatments applied in November and January were the most effective. In experimentally infected molluscs, the parasite was not visible under the stereomicroscope, at least until 50 days post-infection (p.i.). The prepatent period in experimentally infected lambs was 49–79 days p.i. The number of eggs per gram increased with the days p.i. and the parasite burden. The aspartate aminotransferase, alanine aminotransferase, gamma-glutamyl transpeptidase, leukocyte and neutrophil values of infected lambs increased, but those of lymphocytes decreased. Using the enzyme-linked immunosorbert assay technique, the IgG antibody response to excretory–secretory and somatic antigens ofD. dendriticumwas positive from day 30 p.i., although the maximum antibody levels were observed on day 60 p.i. The number of worms per lamb ranged between 30 and 2063. Cholangitis and cholangiectasia of the septal bile and hepatic ducts were observed. The best enzymatic systems for adult and larvalD. dendriticumcharacterization were lactate dehydrogenase, glucose phosphate isomerase and phosphoglucomutase. Genetic variability of adultD. dendriticumwas high using the random amplified polymorphic DNA technique.