Occult hepatitis C virus infection (OCI) is the absence of HCV RNA in serum and the presence of actively replicating HCV RNA in hepatocytes and peripheral blood mononuclear cells (PBMCs), as evidenced by the presence of antigenomic negative sense single-stranded RNA. This study aimed to determine the prevalence of OCI in Egyptian lymphoma patients and assess changes in biochemical parameters in patients with confirmed OCI. The current study was conducted on 100 apparently healthy subjects as control group and 100 patients with lymphoma as a case group. HCV RNA was extracted and detected in both plasma and PBMCs using qRT-PCR. Total protein, albumin, ALT, AST, and total and direct bilirubin were measured in serum. OCI was detected in 6% of the patient group. OCI patients had lower levels of total protein and serum albumin and higher ALT and AST compared with lymphoma patients without OCI. Our study revealed that six out of 100 patients with lymphoma disorders had occult HCV infection (6%). Therefore, the possibility of this infection should be considered in patients with lymphoma.

This study aims to determine the prevalence of Occult Hepatitis B and C Infections among Egyptian injection drug users (IDUs) and identify key risk factors contributing to their occurrence within this high-risk group. In this cross-sectional study, 200 Egyptian IDUs were assessed. Participants were negative for Hepatitis B surface antigen and hepatitis C virus (HCV) RNA, with anti-HCV positive patients who achieved sustained virologic response after treatment included. Quantitative polymerase chain reaction (PCR) was used to detect HCV RNA in plasma and peripheral blood mononuclear cells, while HBV DNA was identified via nested PCR. Comparisons were made between Occult Hepatitis B infection (OBI) positive and OBI negative subgroups, as well as between other comprehensive income (OCI) positive and OCI negative subgroups. A significance level of 0.05 was set, with P-values below this indicating statistical significance. Statistical comparisons between OBI and OCI-positive and negative groups were performed using the Mann–Whitney U test and Chi-square test. OBI was found in 32% of IDUs, while OCI was detected in 42% of IDUs, and was present in 53.6% of seropositive individuals. All OBI patients showed a significant increase in all liver function tests, while OCI patients had significant elevations in alanine transaminase and aspartate transaminase values. HIV coinfection was identified in 39.1% and 26.1% of OBI and OCI cases respectively. OBI and OCI coinfection were detected in 31 patients. Hidden infections such as OBI and OCI remain an overlooked public health issue in Egypt’s IDU population. These findings highlight the need for targeted strategies to address these reservoirs of infection and could inform similar approaches in countries with comparable HBV/HCV epidemiology.

Occult hepatitis C virus infection (OCI) is broadly described as the presence of HCV-RNA in hepatocytes and/or peripheral blood mononuclear cells (PBMCs) in individuals who are HCV-RNA negative in serum by traditional diagnostic techniques. Based on the presence or absence of anti-HCV in serum, two forms of OCI are distinguished as seronegative (anti-HCV and serum HCV-RNA negative) and seropositive (anti-HCV positive and serum HCV-RNA negative). This review aims to estimate the global prevalence rate of OCI among a certain population in terms of disease epidemiology, method of transmission, infection pattern, progression, and treatment. Occult HCV infection is likely linked to liver fibrosis and disease progression. More research is needed to understand the infectivity of OCI patients and the natural course and particular clinical consequences of OCI. It will be interesting to know if direct-acting antiviral (DAA) medications efficiently eliminate HCV RNA in PBMCs or hepatocytes. Finally, some effective OCI screening strategies are advised to target people at risk of HCV infection. Keywords: Occult HCV; peripheral blood mononuclear cells; RNA

Occult hepatitis B (OBI) and C (OCI) infections represent hidden viral states that evade standard serum diagnostics, posing a significant challenge to global hepatitis control, particularly among high-risk groups like injection drug users (IDUs). OBI is characterized by the persistence of replication-competent hepatitis B virus (HBV) DNA within the liver, often as covalently closed circular DNA (cccDNA), or in blood, in individuals who consistently test negative for hepatitis B surface antigen (HBsAg) through conventional assays. This form of HBV infection is marked by low-level replication within hepatocytes, evading immune detection and remaining undetectable by standard HBsAg tests, thus complicating diagnosis and management. OCI, similarly, is characterized by hepatitis C virus (HCV) RNA in liver cells or peripheral blood mononuclear cells (PBMCs) despite undetectable serum levels. OCI can be seropositive, with anti-HCV antibodies indicating past infection, or seronegative, lacking these antibodies and suggesting minimal immune recognition. Due to practices like needle sharing, IDUs face heightened risks of OBI and OCI, which can silently progress to severe liver disease, including cirrhosis and hepatocellular carcinoma (HCC). The frequent co-occurrence of HIV among IDUs further complicates clinical care, emphasizing the need for multi-disease, integrated screening strategies. The development of sensitive diagnostic tools capable of accurately identifying OBI and OCI in high-risk populations is essential to advance the World Health Organization’s (WHO) hepatitis elimination targets for 2030. Enhanced diagnostics and targeted interventions will support early detection, reduce transmission, and contribute to global efforts to eradicate hepatitis in vulnerable populations.