Introduction: Occult HCV infection has a predilection for specific populations such as haemodialysis (HD)
patients. The exact natural course, epidemiology, pathogenesis and clinical importance of OCI are unknown.
We investigated the existence of OCI among local patients undergoing routine HD at a referral hospital in
Pahang, Malaysia. Methods: Serum and peripheral blood mononuclear cells (PMBCs) were collected from
peripheral venous blood samples of seropositive (anti-HCV positive) and seronegative (anti-HCV negative) HD
patients as well as healthy individuals (negative control group). Inclusion criteria for the seronegative
patients included elevated liver enzymes. Both conventional PCR and strand-specific PCR were used to
detect the viral RNA and to indicate active viral replication in PBMCs respectively. Direct DNA sequencing
was done to confirm the viral HCV RNA and their genotypes. Results: In the majority (90-100%) of seropositive
chronic hepatitis C patients, viral RNA was detected in both serum and PMBCs . Meanwhile, out of 22
seronegative patients, 6 (27%) showed active viral replication in PBMCs but no detectable viral RNA presence
in the serum. None of the negative control group had detectable viral RNA. All seronegative patients with OCI
were infected with HCV genotype 3 and two of them (2/6) had a slight elevation of their liver enzymes.
Conclusion: Seronegative OCI does exist among local hemodialysis patients, with normal or persistently
abnormal liver enzyme values. Further investigation is needed to study the mode of viral transmission and
clinical significance of OCI in HD setting.