Table 1.

Characteristics of occult hepatitis C infection (OCI)⁺.

	Secondary OCI∗	Cryptogenic OCI
Evidence of liver injury
ALT elevated	No	Yes
Histological lesions
Inflammatory: minimal to mod.	Occasional	Frequent
Fibrotic: minimal to severe	Frequent	Frequent
Organs involved
Liver	Yes	Yes
Lymphatic system (PBMC)	Yes	Yes
Anti-HCV detection	Positive	Negative∗∗
HCV-RNA detection
Serum	Yes	Yes
PBMC	Yes	Yes
Liver	Yes	Yes
Longevity of persistence	At least 9 years	Unknown

^∗Secondary OCI: residual infection continuing after spontaneous resolution or after achieving apparent SVR following HCV therapy.

^∗∗Antibodies against HCV can be detected in up to 40% in cryptogenic OCI.

⁺Adopted from Pham et al. [19], Liver International, 2010; 502-11.