Reflex viral load testing in dried blood spots generated by plasma separation card allows the screening and diagnosis of chronic viral hepatitis.

Dried blood spots (DBS) have been proposed as an alternative diagnostic technique for chronic viral hepatitis. The aim of this observational study was to correlate serologic HBV, HCV, and HDV status and reflex the respective viral load testing by PSC-DBS samples from capillary blood vs conventional plasma samples in patients with chronic viral hepatitis. Besides, we apply these tests in a prospective study for chronic viral hepatitis diagnosis in a rural region of sub-Saharan Africa. In total, 124 HBsAg-positive patients, 75 anti-HCV positive, 2 with HBV-HCV coinfection, and 13 anti-HDV positive were included. PSC-DBS sensitivity/specificity was 98.4 %/96.2 % for HBsAg detection, 98.7 %/100 % for anti-HCV, and 84.6 %/100 % for anti-HDV. HCV-RNA was quantified in all viremic patients using DBS. Only 42 of 78 (53.8 %) samples with HBV-DNA viremia were quantifiable by DBS. Sensitivity increased to 95.7 % in patients with HBV-DNA levels >2000 IU/mL. There was a high correlation between DBS and venous blood. The prevalence of HBsAg among the 93 individuals tested in Angola was 11 %, and 60 % of cases had detectable HBV-DNA viremia. As a conclusion, PSC-DBS is useful for chronic viral hepatitis screening and reflex molecular diagnosis showing globally high sensitivities and correlation with conventional blood samples.