“…The hemagglutination procedure measures preferentially, though not exclusively, IgM antibodies [11]. Since the initial report in 1955 [19], this method has been widely employed, both in this country and abroad [1,2,6,9,10,12,15,18,32,37,38,40,41]. Also, as reported by HOLMGREN and HANSON [17], this test may detect related K antigens.…”