The presence of gastrointestinal parasites (PGI) was determined in meat sheep from farms in the foothills of the commune of San Clemente Chile through convenience sampling (n=100) between August and November 2022. Faecal samples were collected from the rectum. and were processed using the modified Dennis sedimentation technique for the determination of F. hepatica eggs and the Sheather flotation technique for the determination of nematode and coccidia eggs. In addition, the modified McMaster quantitative technique was performed on the samples. A higher prevalence of parasites from the Trichostrongylidae family (68%) was found, followed by F. hepatica (47%), Nematodirus sp (25%) and Eimeria sp (43%). In addition, the epidemiological variables age, sex and health status were evaluated. The age group was significant (p=0.003) for the age variable in Trichostrongylidae, and the type of health management affected the prevalence of Eimeria (p=0.020); Trichostrongylidae (p=0.001); Nematodirus sp (p=0.04) and F. hepatica (p=0.020). Moderate parasite loads were detected in all cases. Likewise, cases of biparasitism (26%) and multi-parasitism (32%) were detected.

Despite their ecological importance, research on symbionts of amphipods has been limited in South America. The present study provides a comprehensive overview of symbiont organisms in the freshwater amphipods of the genus Hyalella in South America. Our findings reveal various taxa such as Apicomplexa, Microspora, Peritrichia, Folliculinidae, trematodes, nematodes, cestodes and acanthocephalans, often involving complex life cycles. Studies on symbionts have been done almost exclusively in Argentinean Patagonia. The present overview allows us to know the species that use amphipods, to elucidate their lifecycles and to know their occurrence values.

Trichomoniasis, a globally distributed sexually transmitted infection, is caused by the urogenital parasite Trichomonas vaginalis Donn?, 1836 affecting both women and men. The treatment of choice is metronidazole (MTZ). In the present study, 15 samples of vaginal discharge and urine were analysed by sequencing nitroreductase genes (ntr4 and ntr6). An in silico model was structured to illustrate the location of point mutations (PM) in the protein. The ntr4 gene presented four PMs: G76C (10/10), C213G (9/10), C318A (5/10) and G424A (1/10), while the ntr6 gene had eight PMs; G593A (13/13) the most frequent, G72T and G627C, both in 8/13. The PM C213G and A438T generated a stop codon causing a truncated nitroreductase 4 and 6 protein. Docking analysis demonstrated that some models had a decrease in binding affinity to MTZ (p < 0.0001). A high frequency of mutations was observed in the samples analysed that could be associated with resistance to MTZ in Chile.