At the U.S. Centers for Disease Control and Prevention, a combination of tests with purified adult worm antigens is used for antibody detection. All serum specimens are tested by FAST-ELISA using "S. mansoni" adult microsomal antigen. A positive reaction (greater than 9 units/µl serum) indicates infection with "Schistosoma" species. Sensitivity for "S. mansoni" infection is 99%, 95% for "S. haematobium" infection, and less than 50% for "S. japonicum" infection. Specificity of this assay for detecting schistosome infection is 99%. Because test sensitivity with the FAST-ELISA is reduced for species other than "S. mansoni", immunoblots of the species appropriate to the patient's travel history are also tested to ensure detection of "S. haematobium" and "S. japonicum" infections. Immunoblots with adult worm microsomal antigens are species-specific, so a positive reaction indicates the infecting species. The presence of antibody is indicative only of schistosome infection at some time and cannot be correlated with clinical status, worm burden, egg production, or prognosis. Where a person has traveled can help determine which "Schistosoma" species to test for by immunoblot.