Field performance of HBsAg rapid diagnostic tests in rural Ethiopia

Point-of-care rapid diagnostic tests (POC-RDTs) are widely used to screen and diagnose hepatitis B virus (HBV) infection and are often the only available diagnostic tools in resource-limited settings. The aim of this study was to evaluate the validity of three hepatitis B surface antigen (HBsAg) POC-RDTs (Healgen®, Advanced Quality™ and Determine™) in an area with high prevalence of HBV in eastern Ethiopia. Results were compared with a commercial enzyme linked immunosorbent assay (ELISA) as gold standard. Quantification of HBsAg was performed in false negative samples. A total of 511 subjects were screened, of whom 81 (15.9%) were HBsAg-positive with the gold standard. All three POC-RDTs were positive in 65 of the 81 positive samples, yielding a sensitivity (95% confidence interval) of 80.2% (70.3-87.5) and a specificity of 99.8% (98.7-100 for Healgen® and Determine™; 98.6-100 for Advanced Quality™). False negatives were observed in 16 patients associated with low levels of HBsAg (median 1.5 IU/mL). All three POC-RDTs had reasonably high sensitivity and excellent specificity, but false negative results were observed in patients with low titres of HBsAg. Thus, these POC-RDTs might be useful to identify patients in need of HBV treatment, but cannot be recommended as blood donor screening tests.publishedVersio

High Seroprevalence of Autoantibodies Typical of Autoimmune Liver Disease in Eastern Ethiopia: Is Chewing of Khat (Catha edulis) a Triggering Factor?

Background. Recent studies have identified chewing of khat (Catha edulis) as an independent risk factor for liver injury; however, the pathogenetic mechanism remains poorly understood. Case series have found markers of autoimmune hepatitis in patients with khat-related liver disease, suggesting that khat chewing might trigger an autoimmune response. The aims of the present study were (i) to assess the prevalence of autoantibodies typical for autoimmune liver diseases in a healthy population in Ethiopia and (ii) to explore the hypothesis that khat usage triggers autoimmunity. Methods. Consenting adults (≥18 years) without known autoimmune disease or manifest liver disease were included. One-hundred-and-sixty-nine individuals with current khat use were compared to 104 individuals who never used khat. Seroprevalence of antinuclear (ANA), antismooth muscle (SMA), and antimitochondrial antibodies (AMA) were determined and compared between the groups using logistic regression models to adjust for age and sex. Results. Overall, 2.6% of the study subjects were positive for ANA, 15.4% for SMA, and 25.6% for AMA. When comparing khat users to nonusers, ANA was detected in 4.1% vs. 0% (p=0.047), SMA in 16.0% vs. 14.4% (p=0.730), and AMA in 24.9% vs. 26.9% (p=0.704). ANA was excluded from multivariable analysis since there was no seropositive in the reference group. After adjusting for sex and age, no significant association between khat use and SMA or AMA was found. Conclusions. No association between khat usage and the seropresence of SMA or AMA was found, weakening the hypothesis that khat-related liver injury is mediated through autoimmune mechanisms. However, the seroprevalences of AMA and SMA were strikingly high in this Ethiopian population compared to global estimates, suggesting that diagnostic algorithms for autoimmune liver diseases developed in Europe and North America might lead to misdiagnosis of patients on the African continent