Salmonella and shigella surveillance in Hungary, 1972-1976. II. Shigella surveillance.

Shigellae were isolated from 32 399 persons in the bacteriological laboratories of the Public Health Stations between 1972-1976. The number of isolations ranged between 5325 and 8237 yearly. As S. dysenteriae and S. boydii serotypes occurred only in about 1.5% of all isolations, the epidemiological situation was determined by the incidence of S. flexneri and S. sonnei. Except in 1973, S. sonnei constituted the majority in every year. S. sonnei predominance, observed first in the western regions of the country, showed a gradual eastward spread and became characteristic of all localities in 1975-1976. The July-September peak of shigella isolations was associated with S. sonnei, as S. flexneri was distributed practically evenly in every season. The incidence of shigella isolations per 100 000 inhabitants was the lowest in the middle and the highest in the northern parts of the country. Sporadic cases were somewhat more frequent than epidemic outbreaks. Shigellae were isolated in 64.1% from patients and in 35.9% from asymptomatic excreters. The patient : excreter ratio was higher for S. sonnei (70.2 : 29.8) than for S. flexneri (54.6 : 45.4). In the survey period, 14 692 isolations were made in the course of 3278 epidemics; out of these, 11 171 cases were involved in 574 extensive outbreaks. S. sonnei was responsible mainly for school and nursery outbreaks, whereas S. flexneri dysentery predominated in mental wards and in homes for the aged and for mentally retarded children. The prevalent types of S. flexneri were (serological/phage type): 2a/69, 3a/5, 3a/19, 4a/81, 4a/89d and 6/85. The prevalent epidemiological subunits of S. sonnei were (phage/colicin type): 2/0, 2/6, 2/12, 3/12, 6/0, 7/0, 65/0, 65/6 and 65/12.