RESUMEN
In a long term epidemiological survey that included different hosts for Trichinella spiralis among wild and domestic animals, the parasitological and serological screening revealed a high number of positive animals. The incidence of T. spiralis in grazing pigs was high, 21.76% (170 examined) but most of positive animals were lightly infected (0.016-0.02 l/g). While out of 2,394 pigs raised in small private farms, 1.67% were positive with high infection rates, none of the pigs raised on a modern breeding and fattening farm were seropositive. A repeated survey in grazing pigs performed five years later and in the same area, showed the prevalence of seropositive pigs to be still high (22% of 100 examined pigs). The same data were confirmed by detection of specific anti-Trichinella antibodies in Western blotting procedure. One of 2,031 serologically (IgG-ELISA) examined horses from Croatia reacted positively with very high OD values. Different characteristics of biological patterns (RCI, female fecundity, capsule formation, isoenzyme analysis) were found between two well distinguished groups of isolates. The first group consisted of well defined T1 isolates with patterns described by the Reference Centre for Trichinellosis, Rome, Italy. The data obtained by isoenzyme analysis of the representative sylvatic isolate were comparable to T3 characteristics of isolates from foxes in Italy.