Epidemiology of Shigella dysenteriae, type 1 infections, in Dacca urban area

A prospective study of 47 families with an index case of Shigella dysenteriae type 1 was conducted in the urban areas of Dacca. The subsequent infection rates in contacts type 1 were 30.6% and 28.3% in the age groups 0--4 and 5--9. Total secondary infection rate was 20.4% with rates in males higher than in females. Among the contacts 12.5% developed diarrhoea caused by the same serotype, but 22.1% developed diarrhoea with undiagnosed causes. For one hospitalised case there were seven symptomatic cases and 10 infections. All the infected infants age 0--4 developed diarrhoea and one fourth needed hospitalisation; but none aged over 9 needed it. Of these families 19% coincidentally had infections with other shigela types. Many factors were related with the higher infection rate. Use of open source of water was a significant factor. Multiple resistance to antibiotic was found, however, Shigella shiga was sensitive to Ampicillin, Kanamycin, Colistin and Furazolidone.