Study of the association of HLA class I antigens with kala-azar.

HLA class I antigen frequencies were studied in 52 patients with kala-azar and compared with 222 unrelated healthy controls. The relative risk (RR) and etiologic or preventive fraction (EF/PF) were determined for each character, and statistical significance was evaluated with chi 2 with Yates' correction. Results showed that the only antigen with a statistically significant difference was HLA-A26 (15.38 vs. 1.35%; p = 0.004), with RR = 13.27 and EF = 0.142. This indicates a high risk of contracting the disease for HLA-A26-positive individuals and a relatively remarkable influence of this antigen on the prevalence rate of kala-azar.