A serologic study of twenty leptospiral isolates from Malaya, North Borneo and Thailand is reported. Initial serologic typing of these strains by means of the cross agglutination-lysis reactions revealed the presence of seven distinct antigenic leptospiral types. Subsequent antigenic analysis of representative strains indicated the presence in Malaya of L. pyrogenes, Salinem (4 human), L. mankarso (1 human), and an “incomplete” biotype of L. wolffi (2 human, 3 rodent), a “complete” biotype of L. grippotyphosa (1 rodent), L. schüffneri (1 rodent) and a new serotype strain (1 human). In addition L. mankarso was isolated from R. whiteheadi trapped in North Borneo, and L. autumnalis AB was isolated from the six members of the rodent genus Bandicoota, trapped in Thailand.
Classification of the leptospiral isolates based on a modified adoption of the proposed scheme of Wolff and Broom (1954) disclosed the presence of three hitherto undescribed antigenic types, a new serotype designated as L. malaya, an “incomplete” biotype of L. wolffi, designated as L. wolffi A, and a “complete” biotype of L. grippotyphosa designated as L. grippotyphosa AB.
The results of agglutinin absorption studies with the members of the pyrogenes, icterohemorrhagiae, hebdomidis, and grippotyphosa serogroups were consistent with the findings of other investigators on the inter-relationships among the serotype members of these respective groups.