Variations of Invasive Salmonella Infections by Population Size in Asante Akim North Municipal, Ghana

Background. The Typhoid Fever Surveillance in Africa Program (TSAP) estimated adjusted incidence rates (IRs) for Salmonella enterica serovar Typhi and invasive nontyphoidal S. Enterica serovars (iNTS) of >100 cases per 100 000 person-years of observation (PYO) for children aged <15 years in Asante Akim North Municipal (AAN), Ghana, between March 2010 and May 2012. We analyzed how much these rates differed between rural and urban settings. Methods. Children recruited at the Agogo Presbyterian Hospital and meeting TSAP inclusion criteria were included in the analysis. Towns with >32 000 inhabitants were considered urban; towns with populations <5200 were considered rural. Adjusted IRs for Salmonella bloodstream infections were estimated for both settings. Setting-specific age-standardized incidence rates for children aged <15 years were derived and used to calculate age-standardized rate ratios (SRRs) to evaluate differences between settings. Results. Eighty-eight percent (2651/3000) of recruited patients met inclusion criteria and were analyzed. IRs of Salmonella bloodstream infections in children <15 years old were >100 per 100 000 PYO in both settings. Among rural children, the Salmonella Typhi and iNTS rates were 2 times (SRR, 2.2; 95% confidence interval [CI], 1.3-3.5) and almost 3 times (SRR, 2.8; 95% CI, 1.9-4.3) higher, respectively, than rates in urban children. Conclusions. IRs of Salmonella bloodstream infections in children <15 years old in AAN, Ghana, differed by setting, with 2 to nearly 3 times higher rates in the less populated setting. Variations in the distribution of the disease should be considered to implement future studies and intervention strategies.