Hidden Threats: Understanding the Epidemiology and Clinical Features of Occult HBV and HCV in Injection Drug Users.

Introduction: Occult infections of hepatitis B and C represent a significant challenge, as infection spreads among people who inject drugs. Occult hepatitis B can be defined as the presence of viral genetic material in blood or liver tissue without surface antigen detection, while occult hepatitis C involves viral RNA in liver and immune cells and remains undetectable in plasma. Traditional blood tests are often unable to detect these infections, making developed molecular diagnostics essential. Addressing these hidden infections requires targeted screening strategies to reduce their spread. Aim: This study aimed to highlight the epidemiological and clinical factors influencing the prevalence of occult infections in individuals with co-existing conditions by understanding their distribution, risk factors, and clinical consequences. Methods: A cross-sectional design was used to assess 200 injection drug users from Egypt. Injection drug users who were negative for hepatitis B surface antigen with the absence of hepatitis C viral RNA in plasma participated in this study; positive results for hepatitis C antibodies, showing sustained virologic response post-treatment, were also included. The presence of hepatitis C RNA virus in plasma and peripheral blood mononuclear cells was detected by quantitative polymerase chain reaction, whereas the presence of hepatitis B virus DNA was detected via the nested polymerase chain reaction technique. Results: High levels of liver enzymes and bilirubin, with reduced total protein, albumin, and albumin-to-globulin ratio, were detected among co-infected individuals. Three individuals diagnosed with OBI-OCI coinfection had human immunodeficiency virus, representing 9.7% of total co-infected cases. Conclusions: The results assure the importance of expanding public health initiatives to effectively identify and control hidden infections within high-risk populations.