Strongyle-Type Gastrointestinal Nematode Egg Positivity, Fecal Egg Counts, and Associated Factors in Sheep from Guanujo Parish, Ecuador

Background: Strongyle-type gastrointestinal nematodes are among the most important parasitic infections affecting sheep production because of the health and economic losses they cause. Aim: The aim of this study was to determine the positivity, parasite burden, and factors associated with positivity to strongyle-type gastrointestinal nematode eggs in sheep from Guanujo parish, Ecuador. Methods: A quantitative, descriptive, cross-sectional study was conducted between November 2025 and March 2026. Seventy fecal samples were collected individually via rectal sampling from sheep randomly selected within 14 participating farms. The samples were analyzed using coproparasitological techniques with the modified McMaster method to quantify eggs per gram of feces (EPG). Subsequently, univariate analysis and multivariable logistic regression were performed to identify factors associated with positivity for strongyle-type gastrointestinal nematode eggs. Results: The overall positivity was 54.3% (38/70), with a mean parasite burden of 1150 EPG. Mild and moderate infections predominated, although severe infections were also detected. After multivariable adjustment, younger age was consistently associated with positivity. High stocking density was associated with positivity in the primary model, although this association was less stable in the mixed-effects sensitivity analysis. Sheep younger than 12 months showed higher odds of positivity than adults (adjusted OR = 8.75; 95% CI: 3.42–22.38; p < 0.001), while animals from farms with high stocking density also showed higher odds of positivity (adjusted OR = 2.69; 95% CI: 1.21–5.97; p = 0.015). Conclusions: Younger age was the most consistent factor associated with strongyle-type gastrointestinal nematode egg positivity. High stocking density showed higher odds of positivity in the primary analysis, but this association was not statistically significant in the mixed-effects sensitivity analysis and should therefore be interpreted cautiously.