Rapid Clearance and Frequent Reinfection With Enteric Pathogens Among Children With Acute Diarrhea in Zanzibar

Background. Acute infectious gastroenteritis is an important cause of illness and death among children in low-income countries. In addition to rotavirus vaccination, actions to improve nutrition status, sanitation, and water quality are important to reduce enteric infections, which are frequent also among asymptomatic children. The aim of this study was to investigate if the high prevalence of these infections reflects that they often are not cleared properly by the immune response or rather is due to frequent pathogen exposure. Methods. Rectal swabs were collected at time of acute diarrhea and 14 days later from 127 children, aged 2-59 months and living in rural Zanzibar, and were analyzed by real-time polymerase chain reaction targeting multiple pathogens. Results. At baseline, detection rates >20% were found for each of enterotoxigenic Escherichia coli, Shigella, Campylobacter, Cryptosporidium, norovirus GII, and adenovirus. At follow-up, a large proportion of the infections had become cleared (34-100%), or the pathogen load reduced, and this was observed also for agents that were presumably unrelated to diarrhea. Still, the detection frequencies at follow- up were for most agents as high as at baseline, because new infections had been acquired. Neither clearance nor reinfection was associated with moderate malnutrition, which was present in 21% of the children. Conclusions. Children residing in poor socioeconomic conditions, as in Zanzibar, are heavily exposed to enteric pathogens, but capable of rapidly clearing causative and coinfecting pathogens.