Phage types and epidemiological significance of Salmonella enteritidis strains in Hungary between 1976 and 1983.

In Hungary, 14 819 human Salmonella enteritidis strains were isolated between 1976 and 1983. Phage type was determined of 10 132 human strains originating from 6852 foci, and of 711 strains isolated from animals and water in this period. The human strains were typable in 99.4% and they belonged into 21 phage types. Five phage types (1, 4, 7, 16 and 17) were more frequent than 1%. Phage type 7 predominated among the strains isolated between 1976 and 1980, including 65.6%-89.3% of the strains. There was a change in the prevalence of phage types from 1980-1981, as phage type 7 was ousted by phage type 1. The date of the change in the predominance of phage types coincided with the considerable increase of S. enteritidis isolates; the number of isolates was nearly fivefold in 1980 of that in 1976. Phage type 7 frequent in the first period proved to be homogeneous; the strains could not be subdivided either by the temperate phages carried by them or by other phages. The incidence of phage types 1 and 7 was nearly the same among the strains derived from animals, food, water and hygienic control examinations, and there was no temporal difference in the frequency of the two phage types as it was observed among the human strains. The human strains originated in 49.5% from outbreaks and in 50.5% from sporadic cases in the country. Of the strains examined for phage type during the eight-year period, 41.9% were isolated from 23 field epidemics, 84 community outbreaks and 757 family infections. Analysing the regional spread of S. enteritidis, the increase in the number of isolates was the highest in counties Tolna, Bács-Kiskun, Somogy and Györ-Sopron. The predominance of phage type 1 was observed in counties Békés, Borsod, Csongrád, Györ-Sopron, Hajdu-Bihar, Pest and Tolna. It was obvious in the case of county Tolna that the source of infection was contaminated egg and baby chicken. Phage type 7 predominated in counties Komárom, Vas and Veszprém. Phage type 4 circulated in counties Csongrád and Pest, phage type 17 in county Fejér and phage type 2 in county Hajdú-Bihar.