Strongyloides stercoralis in type 2 diabetes mellitus: discordant stool and serologic findings in an endemic Brazilian population.

Strongyloides stercoralis is a neglected soil-transmitted helminth capable of causing hyperinfection and disseminated disease in immunocompromised hosts. Type 2 diabetes mellitus (T2D) is associated with immune dysfunction and may increase susceptibility to strongyloidiasis, although data in diabetic populations remain limited. In endemic areas, discrepancies between stool-based and serologic tests may impair accurate diagnosis. We conducted a cross-sectional study in an endemic area of Central Brazil including 80 adults with T2D and 80 non-diabetic controls. Three stool samples per participant were examined by spontaneous sedimentation (Lutz), Rugai, and agar plate culture. Serum IgG anti-Strongyloides antibodies were detected by ELISA using an alkaline extract of Strongyloides venezuelensis larvae, and ELISA-reactive samples were confirmed by immunoblotting. Intestinal parasites or commensal protozoa were identified in 37.5 % of T2D patients and 32.5 % of controls, with no significant difference. Stool positivity for S. stercoralis was low in both groups (1.2 % in T2D vs 7.5 % in controls). Conversely, IgG ELISA seropositivity was significantly higher among T2D patients (31.2 %) than in controls (16.2 %; p = 0.0122). Among ELISA-reactive samples, immunoblot confirmation was obtained in 60 % of T2D patients and 69 % of controls. These results reveal a clear discordance between parasitologic and serologic findings, particularly in T2D patients, who exhibited increased serologic evidence of S. stercoralis infection despite minimal stool-based detection. In this endemic setting, the combination of ELISA followed by immunoblotting emerges as a valuable complementary strategy for diagnosing strongyloidiasis, especially in individuals with T2D who may present altered immune responses and lower sensitivity to stool-based methods.