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Between February 2007 and January 2009, a total of 776 slaughtered animals were examined for the presence of Trematoda in the liver, gall bladder, oesophagus and stomach (rumen and reticulum). Data collected were analysed by the age and breed of the animals. The percentage of cattle from which Trematoda were found was 38 per cent (95 per cent confidence interval [CI] 35 to 41 per cent); 28 per cent (95 per cent CI 25 to 31 per cent) had Fasciola hepatica, 12 per cent (95 per cent CI 10 to 14 per cent) Calicophoron daubneyi and 6 per cent (95 per cent CI 4 to 8 per cent) Dicrocoelium species. A significantly high prevalence of fasciolosis and dicrocoeliosis was observed in cattle over 10 years of age. Autochthonous Rubia Gallega cattle had the highest prevalence of fasciolosis and crossbred cattle had the highest prevalence of dicrocoeliosis (P<0.05). Twenty per cent (95 per cent CI 15 to 25 per cent) of the cattle positive for Fasciola also had Calicophoron species; 10 per cent (95 per cent CI 6 to 14 per cent) also had small liver flukes (Dicrocoelium species).

Several parasitic infections such fasciolosis, toxocariosis or ascariosis are important zoonoses. During the infection with Fasciola hepatica, Toxocara canis and Ascaris suum, an important intraorganic phase in their hosts takes place, releasing antigens responsible for a humoral immune response, which enables the diagnosis of that parasitosis. A study to identify the existence of cross-reactivity among the excretory/ secretory antigens of F. hepatica, T. canis and A. suum was developed. One group of Sprague-Dawley rats was infected with 20 metacercariae of F. hepatica and another group remained uninfected as control. By means of an Indirect-ELISA, the rat humoral immune response (IgG and IgM) against the excretory/secretory antigens of F. hepatica was analysed and measured for cross reactivity with T. canis and A. suum. IgM cross-reaction was mainly observed in the first 10 weeks post-infection. IgG cross-reaction was observed throughout the study, and was maximal at the 2-3 weeks and 3-6 weeks post-infection, which corresponds to the intraorganic migratory phase of these parasites. The western-blot showed that the rat IgG recognised three proteins of 190, 160 and 33 kDa in the antigens from F. hepatica, T. canis and A. suum. The existence of cross-reactivity among these antigens seems to demonstrate also the presence of structural similarities, such as tegumental proteins. These results should be consider when immunoassay probes are used in the diagnosis of parasitic infections.

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