Prevalence and Associated Risk Factors of HTLV-1 and Co-infections of Blood-Borne Viruses in Birjand, Iran's Eastern Border.

Background: Blood-borne viruses (BBVs) are one of the most important public health concerns. South Khorasan has a long border with Afghanistan and concern has risen there about blood-borne oncogenic viral infections. The aim of the present study was to evaluate the prevalence and associated risk factors of human T-lymphotropic virus 1 (HTLV-1) and co-infections of BBVs in Birjand, Iran's eastern border.

Methods: In this cross-sectional study, 3441 subjects were tested for sero-prevalence of HTLV-1 by ELISA. The data on demographic features, HTLV-1-related risk factors and other characteristics of the population were analyzed by Pearson chi-square and logistic regression tests. Finally, the co-infection of BBVs was evaluated in the study.

Results: The prevalence of HTLV-1 was 0.3% (95% CI: 0.12-0.48). Notably, the sero-prevalence of HIV, hepatitis B virus (HBV), hepatitis D virus (HDV), and hepatitis C virus (HCV) in our previous studies was reported at 0%, 0.2%, 1.2% and 1.6%, respectively. The results indicated that the occurrence of HTLV-1 infection was associated only with the history of hospitalization (odds ratio [OR]: 0.27, 95% CI: 0.07-0.97, with P = 0.04). The co-infection of HBV with HCV was the most common (2.35%), while a co-infection rate of 1.17% was found for both HBV/HTLV-1 and HBV/HDV.

Conclusion: Although a higher prevalence of the viruses was expected, it was close to the overall Iranian population. With respect to close relationship with an HTLV-1 endemic area (Mashhad and Neyshabour), the prevalence is very low; however, more attention is needed. Our findings reinforce the importance of increasing knowledge about BBV-related health risk behaviors to prevent the emergence of new cases, especially in low-risk populations.