Epidemiologic investigation of an outbreak of Shiga bacillus dysentery in an island population.

An epidemic of dysentery broke out in St. Martin island during May through July 1973. The epidemic was caused by Shigella dysenteriae type 1. The dysentery could not be controlled by conventional antibiotics and other antidysenteric drugs. The average attack rate was 32.9%. The age specific attack rate was highest in the age group 1-4 years (52.2%). The attack rates were higher in smaller families. The rates were not greatly different amongst people using different sources of water. The overall death rate was 2.1%. The overall infection-to-death rate was 6.4% but amongst children less than a year old, it was 41.1%. A common source outbreak was unlikely. The higher attack rate in smaller families suggested limited possibility of person to person spread. No particular water source could be implicated with higher attack rate. Flies may have played an active role in transmission.