The haemagglutination test for toxoplasma antibodies.

Four hundred and forty-six patients' sera from a hospital blood transfusion department in Newcastle were examined for toxoplasma antibodies by a haemagglutination test. Forty per cent. of the sera gave positive reactions, and an increase in the percentage of positive sera was found with increasing age, rising to over 60% at the age of 70 and over. A wide range of titres was demonstrated amongst positive cases, the highest titres approaching those obtained in two cases of active toxoplasmosis.In a separate survey, no quantitative agreement was found between dye test titres and haemagglutination titres.