The relationship between the human leukocyte antigen system and Crimean-Congo hemorrhagic fever in the Turkish population.

Objectives: The human leukocyte antigen (HLA) molecules have been shown to be important genetic factors in several diseases. In this study we aimed to evaluate the possible role of HLA genes in the course of Crimean-Congo hemorrhagic fever (CCHF) infection.

Methods: A total of 57 adult patients with CCHF and 43 healthy controls living in the same regions as the patients were included in the study. Severe cases were defined according to previously reported severity criteria.

Results: The frequency of HLA-A*02 was found to be significantly higher in the patients than in the healthy controls (p=0.021). However, a significantly lower frequency of HLA-B*27 was observed in the patients than in the healthy controls (p=0.01). The relative risk (RR) of HLA-A*02 allele for CCHF was found to be 1.93 (95% confidence interval 1.11 < RR < 3.36). With regard to severe and non-severe cases, there was a significantly greater frequency of HLA-A*23 in severe cases (p=0.014).

Conclusions: The results of this study indicate that while some HLA alleles could constitute a risk factor for acquiring CCHF infection, others could have a protective role against the disease. This study also presents the impact of genetic risk factors on the clinical course of the disease.