Spatial and spatiotemporal patterns of typhoid fever and investigation of their relationship with potential risk factors in Iran, 2012–2017

Typhoid fever is a global infectious disease which remains a severe health problem in Asia and Africa. In subnational levels of Iran, environmental and socio-economic properties are often so divergent, that can have a major effect on the incidence of typhoid fever. We used the data of MOHME that has reported 2474 cases of typhoid fever from 20th Feb 2012 to 31st Dec 2017 in Iran. First, we ran a spatial autocorrelation analysis to see whether there is any spatial trend in incidence cases and find the high-high clusters of typhoid (at different confidence levels) using Local indicators of spatial association (LISAs). To explore the spatial and temporal patterns of typhoid fever and examine their relationship with climatic and socio-economic variables; we have employed a spatiotemporal zero-inflated Poisson (ZIP) model in a Bayesian framework. Our results show thirteen High-High clusters and windspeed (RR [95% CrI] = 1.39 [1.15–1.69]), public sewerage system (RR [95% CrI] = 0.76 [0.63–0.92]), years of schooling (RR [95% CrI] = 0.78 [0.65–0.95]), wealth index (RR [95% CrI] = 0.59 [0.55–0.63]) and urbanization (RR [95% CrI] = 0.6 [0.48–0.76]) as variables that are importantly associated with typhoid fever incidence. Therefore, typhoid fever is spatially clustered with a high incidence in children and adolescents. Windy, poor, rural, and uneducated areas are high-risk regions that can be controlled by proliferating the standard sewerage networks, which eventually leads to safer water supplies.