Epidemiology of gastrointestinal parasitism and field applicability of FAMACHA© in indigenous goats of Southern India.

Gastrointestinal parasitism severely impacts small ruminant production in tropical regions. This study investigated prevalence, risk factors, infection intensity, and co-infection patterns in 1013 goats across five districts in Southern India, while evaluating the field applicability of FAMACHA© scoring as a practical clinical indicator. Overall parasite prevalence was 80.4%, dominated by strongyle nematodes (84.9% of infected animals) and Eimeria spp. (57.3%), with 71.5% mixed infections. Multivariable logistic regression identified breed, sex, season, age, and deworming history as independent predictors of infection. Molai Adu goats exhibited the highest risk (Adj OR = 2.65, p < 0.001), females exhibited a 2.09-fold higher risk of infection compared to males (p < 0.001), and animals > 18 months had substantially lower risk (Adj OR = 0.39, p < 0.001). Non-dewormed animals had 2.79 times higher odds of infection (p < 0.001) with markedly greater mean EPG (718.3 vs. 329.2). Crucially, FAMACHA© scores strongly correlated with infection intensity (r = 0.615, p < 0.001), with geometric mean EPG increasing 15-fold from non-anemic animals (32 eggs/gram) to severely anemic animals (484 eggs/gram) (p < 0.001 for all pairwise comparisons). This dose-response relationship strongly supports the use of FAMACHA© as a practical, non-invasive field-based indicator of clinically relevant gastrointestinal nematode infection. Strategic interventions combining seasonal deworming, targeted treatment of vulnerable groups, and FAMACHA©-guided selective deworming are essential for sustainable parasite control in tropical goat systems.