Phage-typing of Salmonella weltevreden based on lysogeny. II. Epidemiological usefulness of the system and geographical distribution of its phage-types.

Nine hundred and forty-six strains of Salmonella weltevreden isolated in different states of India during 1958-1974 and 124 strains from Australia, Burma, Holland, Hong Kong, New Zealand, Papua New Guinea, the Philippines, Thailand, the United States and Vietnam during 1953-1971 were phage-typed according to the phage-typing scheme described in the first part of this paper (Sood and Basu, 1977). The epidemiological incidence and geographical distribution of phage-types of Salmonella weltevreden were studied. All the phage-types were present in India, the predominant phage-types being b, d and i. Phage-type g was isolated exclusively from India. All the 14 strains from Hawaii belonged to phage-type i. Phage-type h was the most predominant phage-type in Vietnam. The 15 strains isolated from Papua New Guinea in 1965, which were supposed to have originated from a single source, belonged to 3 phage-types. Except these cultures all the available epidemiologically related strains were of uniform phage-types - a finding which establishes the epidemiological validity of the scheme.