[Immunodiagnostic tests for bilharziasis. IV. Demonstration of antibody in blood and serum eluates collected on filter paper discs (author's transl)].

Serum and blood samples dried on filter paper discs and normal sera were collected from 142 Liberians with proven schistosomiasis and 25 Liberians without schistosomiasis. These samples were tested by the indirect hemagglutination test (IHA) employing lyophilized sheep erythrocytes sensitized with either cercarial or adult Schistosoma mansoni antigens. The following results were obtained: Out of the 142 sera collected from the schistosomiasis patients 130 (91.5%) reacted with the cercarial antigen and only 89 (62.6%) reacted with the adult S. mansoni antigen. None of the 25 sera from persons free of schistosomiasis reacted with either antigen. The sensitized lyophilized erythrocytes showed no loss of antibody activity after laboratory storage at 4 degrees C for 4 months which was interrupted twice for 16 hours each during shipment. Filter paper serum and blood samples were stored at -25 degrees C up to 84 days with 16 hours interruption during shipment. 77.6% of the eluates from blood showed the same antibody titer levels as in normal serum; 10% showed lower antibody titers and 11.5% had negative results compared with normal serum. Results obtained with eluates from dried serum were somewhat better. An additional storage of the dried blood specimens for ten days at room temperature resulted in a rise of the proportion of negative titers from 11.5% to 34.1%. This loss of antibody activity was found in two thirds of the samples with low antibody titers. The results indicate that blood and serum samples dried on filter paper platelets should be stored at low temperatures (-25 degrees C) to preserve the antibody response.