Abstract

An epidemiological study of 36 U.S. Marines living in a barracks and exposed to infectious hepatitis was made, and the ability of their sera to agglutinate day-old chick erythrocytes was found to be abnormally high in 52·8% of the group. The other groups of American Servicemen similarly exposed showed no such deviation from the normally expected incidence of raised titres. An unexplained, abnormally high incidence of raised titres was found in several control groups. The titres appeared to be unaffected to any significant degree by gamma globulin prophylaxis or yellow fever immunization.