Recombinant antigens from hepatitis E virus (HEV) open-reading frames 2 and 3 were expressed in Escherichia coli as cytidine monophosphate-2-keto-3-deoxyoctulosonic acid synthetase (CKS) fusion proteins, purified, and used to develop an EIA for the detection of antibodies. Serologic results were compared with those of previous assays by testing 102 samples from an HEV outbreak in Somalia. This CKS/HEV EIA detected anti-HEV in all 97 sera found reactive previously and in an additional 2 samples, which were shown to be true HEV-positive samples by supplemental peptide and Western blot tests. The CKS/HEV EIA and supplemental assays were then used to determine seroprevalence of HEV worldwide. HEV seroprevalence ranged from 1% to 25%, with higher rates found in Middle Eastern countries. Also, 7%-14% of acute cases of non-A, -B, or -C hepatitis were HEV-positive. Thus, this CKS/HEV EIA appears useful for detecting anti-HEV in various populations.