Interleukin-17 (IL-17) contributes to cutaneous antifungal immunity, whereas the significance of circulating immunoglobulin A (IgA) in dermatophytosis remains uncertain.

To compare serum IL-17 and IgA between patients with mycologically confirmed dermatophytosis and apparently healthy controls in Basra Governorate, Iraq, and explore their discriminatory performance.

This hospital-based case–control study enrolled 30 patients and 27 controls between October and December 2025. Cases required positive 10% potassium hydroxide microscopy and dermatophyte culture. Serum markers were measured by enzyme-linked immunosorbent assay. Analyses included Mann–Whitney tests, pooled Spearman correlations, and exploratory receiver operating characteristic analysis.

Median IgA was higher in patients than controls (5.65 [interquartile range, 3.87–9.87] versus 2.46 [1.34–4.28] U/mL; P < 0.001), whereas IL-17 was lower (5.03 [1.39–8.19] versus 14.71 [10.69–17.08] pg/mL; P < 0.001). Median age was 24 years in both groups, but children younger than 10 years were over-represented among cases. The pooled IgA–IL-17 correlation was weakly inverse (rho = −0.263; P = 0.048). Areas under the curve (AUCs) were 0.822 (95% confidence interval, 0.713–0.930) for IgA and 0.911 (0.831–0.991) for low IL-17. Exploratory IL-17 < 10 pg/mL sensitivity was 83.3% (66.4–92.7%) and specificity 85.2% (67.5–94.1%).

Dermatophytosis was associated with lower circulating IL-17 and higher assay-reported IgA. These unadjusted associations and internally evaluated thresholds support further age-adjusted, prospective, tissue-level investigation and independent validation.