Daniela Poo-Muñoz

Cystic echinococcosis (CE), caused by Echinococcus granulosus sensu lato (s.l.), is a significant zoonotic disease affecting livestock and public health worldwide, particularly in endemic regions such as La Araucanía, Chile. This study evaluated the role of cattle in the transmission dynamics of E. granulosus sensu stricto (s.s.) by morphologically and molecular characterizing hydatid cysts (HC) collected from cattle, sheep, pigs, and goats. A total of 123 cysts were obtained from a local slaughterhouse, with cattle contributing the majority of samples (n = 94). Fertility was highest in sheep (76.2%) and low in cattle (3.2%), while cysts from pigs and goats were infertile. PCR amplification and sequencing of the cox1 gene confirmed the predominance of genotype G1 (98.1%), with two additional haplotypes (Eg^B and Eg^C) identified in cattle and sheep. Two cattle samples harbored genotype G3. Phylogenetic analyses grouped all sequences within the E. granulosus s.s. complex. The results corroborate the role of cattle as important sentinels for environmental surveillance of CE due to their exposure and traceability but highlight their lower competence in parasite transmission to definitive hosts compared with sheep. The genetic diversity observed aligns with previous findings in Chile, underscoring the epidemiological significance of E. granulosus s.s. and genotype G1 in the region.