Serological and biochemical follow-up in cattle naturally infected with Fasciola hepatica, and comparison with a climate model for predicting risks of fasciolosis

Several biological parameters were measured in 31 heifers naturally infecte d with Fasciola hepatica during one grazing season in the Belgian Ardennes. A forecast model based on daily temperature used to assess the risk of fas ciolosis was fitted to this assay. Cattle were turned out to two pastures. Each pasture was divided into two plots: one was treated with calcium cyana mide and the other was left untreated. The Lymnaea truncatula snails were c ounted on three different occasions. The results indicated a poor molluscic ide efficiency. Body weight gains, anti-Fasciola antibody levels, faecal eg g counts, levers of sorbitol dehydrogenase (SDH) and gamma-glutamyl transfe rase ( FT), packed cell volumes, white blood cells and differential leucocy te counts were determined monthly. No statistically significant difference was observed between animals from the two plots regardless of the recorded data. No correlation was found between body weight gains and other biologic al data. The sampling date had a significant effect on the antibody respons es within a same group, and on the enzymatic levers for all groups combined . The forecast results were consistent with the recorded data. Temperature was a major bioclimatic Constraint on the transmission of life cycle, and r isk of infection occurred mainly in late spring (May/June) and in early Sep tember. Current results might be used to issue advice on the need for fluki cide treatment of cattle. The indicators of the infection considered alone were useless and it is concluded that herd diagnosis of fasciolosis may rel y on the rise of specific antibody levels, possibly associated with an incr ease in hepatic enzyme activities. (C) Inra/Elsevier, Paris.