Mixed-Effects Poisson Modelling of Gastro-intestinal Parasites in Goats and Efficacy of Fenbendazole Treatment

Background Small ruminant production is important for food security in Papua New Guinea (PNG), yet research on goat health management, particularly gastrointestinal parasitism, remains limited. Understanding parasite burdens and treatment efficacy is essential for improving productivity. Methods A five-month prospective cross-sectional study with repeated measures was conducted on a university goat farm in PNG. Fecal egg counts (EPG) were determined using a modified McMaster technique and log-transformed for analysis. The effects of host factors (sex, age, breed, body condition score) and treatment on log(EPG) were evaluated using multivariable mixed-effects Poisson regression. Results Log-transformation normalized the skewed EPG data. Fenbendazole treatment reduced egg counts of major parasites, including Haemonchus contortus and Trichostrongylus spp. Higher EPG was associated with male sex (19.2% higher expected log(EPG), P = 0.015) and higher FAMACHA scores (8.6% increase per unit, P = 0.022). Younger goats also had significantly higher counts. Breed and body condition score were not significant predictors. Conclusion Fenbendazole was effective at the recommended dose under farm conditions. However, FAMACHA scores did not reliably correlate with EPG in this short-term study. Targeted deworming should consider sex and anemia status, while further research is needed to validate FAMACHA for EPG prediction in PNG goat systems.