Hepatitis B surface antigenaemia and alpha‐foetoprotein detection from dried blood spots: applications to field‐based studies and to clinical care in hepatitis B virus endemic areas

Abstract

In many resource-limited regions with endemic hepatitis B virus (HBV), there is limited infrastructure to collect, process, transport, and store blood samples for identification of persons with chronic HBV infection or with hepatocellular carcinoma (HCC). We describe the application of a simple technique using commercially available kits for detection of HBV surface antigen (HBsAg) and alpha-foetoprotein (AFP) in dried blood spots (DBS) collected on filter paper. Study participants included subjects with and without chronic HBV infection and subjects with HCC or cirrhosis. Three to five blood drops were dried on filter paper. Dried blood (equivalent to 20 muL) was eluted and tested for HBsAg by Determine(TM) HBsAg and for AFP by counter-current immuno-electrophoresis and radio-immunoassay (RIA). The primary analysis focused on comparison of DBS results to serum testing results as the gold standard. The sensitivity of DBS for detecting chronic HBV infection was 96% (98-98) with specificity of 100% (CI 99-100). Sensitivity of DBS in detecting AFP compared with serum RIA was 73% (60-86) with specificity of 90% (81-98). Both HBsAg and AFP recovery were unaffected when DBS were left at room temperature (30-33 degrees C) and under humid conditions for up to 28 days prior to elution. We conclude that DBS can be reliably used as an economical and logical alternative for detection of HBsAg in chronically infected patients and for AFP-based diagnosis of HCC in clinical situations which preclude adequate collection and processing of blood samples. Both research-oriented field studies and routine clinical care may benefit from application of these techniques in resource-limited settings.

The prevalence of hepatitis B virus markers in a cohort of students in Bangui, Central African Republic

“…This observation requires further investigation to determine the reason why this study shows such a very low detectable anti-HBs antibody level. This is not due to a loss of the sensitivity of the DBS as it had been shown with the preliminary tests as well as observations from other studies [14,17]. Although infection in neonates can explain an immunotolerance phenomenon, the absence of anti-HBs in young adults is puzzling and requires further investigation.…”

“…The dried blood spot technique gives reliable results with sensitivity and specificity almost identical to serum testing. The collection of blood samples is made easy using finger pricks [15-17]. It reduces the cost of the survey and, as it is almost painless, the risk of refusal is minimized (and there was none in this study).…”

An Overview of the Clinical Use of Filter Paper in the Diagnosis of Tropical Diseases

“…DBS were also used successfully to detect the humoral response to HAV vaccination 37. Only two studies have examined the use of DBS samples for hepatitis B (HBV) serology, yielding different performances for three serological HBV assay types, with sensitivities ranging from 78% (for anti-HBs) to 97% (for HBs-Ag) 38,39. The inclusion of combined HCV, HBV, and HIV diagnoses on one DBS could be a potentially cost-effective way to expand screening in resource-poor and remote populations.…”

Long term stability of HBsAg, anti-HBc and anti-HCV in dried blood spot samples and eluates

“…Other studies have reported unaffected detection of HBsAg from DBS stored in hot (30-33 • C) and humid conditions for up to 28 days prior to elution [22].…”