Enhancement of sensitivity of the haemagglutination test for echinococcosis by use of Staphylococcus aureus protein A.

A modification of the indirect haemagglutination test is described for the serodiagnosis of echinococcosis. In the modified test the Cowan I strain of Staphylococcus aureus, which contains protein A, was used to enhance haemagglutination of sensitised red cells. The test was performed in parallel with the indirect haemagglutination test on 31 sera from surgically-confirmed cases of hydatid disease and on 45 sera from healthy blood donors. Use of S. aureus protein A enhanced the sensitivity of the test and greatly increased the titres obtained with most of the sera. None of the sera from healthy blood donors exhibited a titre greater than 64, whereas all but two of the sera from cases of hydatid disease exhibited titres greater than 128. The immunoassay is simple, inexpensive and requires little technical skill. It has the potential for wide application in the serodiagnosis of echinococcosis.