Non-typhoidal Salmonella intestinal carriage in a Schistosoma mansoni endemic community in a rural area of the Democratic Republic of Congo.

Background: Clinical observations and animal studies have suggested that Salmonella intestinal carriage is promoted by concurrent Schistosoma infection. The present study assessed association of Salmonella intestinal carriage and Schistosoma mansoni infection among individuals in a Schistosoma endemic area in sub-Saharan Africa. Methods: From November 2015 to March 2016, a cross-sectional community-wide study was conducted in Kifua II, a rural village in Kongo Central Province, Democratic Republic of Congo. Stool samples were collected and analyzed for Salmonella intestinal carriage (culture) and Schistosoma mansoni infection (Kato Katz microscopy with determination of egg load). Salmonella Typhimurium and Enteritidis isolates were assessed for genetic similarity with blood culture isolates obtained during the same period in a neighboring hospital using multi-locus variable-numbers tandem repeat analysis (MLVA). Results: A total of 1,108 participants were included (median age 15 years (IQR: 7–36), male-to-female ratio of 1:1.1). The overall prevalence of Schistosoma mansoni infection and non-typhoidal Salmonella carriage was 51.2% (95% CI: 48.2–54.1) and 3.4% (95% CI: 2.5–4.7) respectively, with 2.2% (95% CI: 1.5–3.2) of participants coinfected. The proportion of Salmonella carriage tended to be higher among Schistosoma mansoni infected participants compared to non-infected participants but this difference did not reach statistical significance (4.2% versus 2.6%, p = 0.132). However, the proportion of Salmonella carriage among participants with a heavy Schistosoma mansoni infection was significantly higher compared to those with a light and moderate infection (8.7% versus 3.2%, p = 0.012) and compared to Schistosoma mansoni negatives (8.7% versus 2.6%, p = 0.002). The 38 Salmonella isolates comprised five and four Enteritidis and Typhimurium serotypes respectively, the majority of them had MLVA types identical or similar to those observed among blood culture isolates. Conclusion: Salmonella intestinal carriage was associated with a heavy intensity of Schistosoma mansoni infection. Further studies are needed to address causation. Author summary: Salmonella intestinal carriage may be facilitated by infection with Schistosoma mansoni, which is a flatworm that lives in the small blood vessels of the human intestinal tract. This situation has been described in tropical low and middle income countries, where both pathogens are endemic. The present study aimed to assess the association of Salmonella intestinal carriage with Schistosoma mansoni infection in Kifua II village, located in the Kongo Central province of the Democratic republic of Congo. We collected stool samples from 1,108 inhabitants of the village and analysed them for Salmonella (culture) and Schistosoma mansoni eggs (microscopy). Our findings showed that 3.4% of the participants had Salmonella in their stool and 51.2% were infected with Schistosoma mansoni. There was no association between overall Schistosoma infection and Salmonella carriage but Salmonella carriage was significantly higher among participants with heavy Schistosoma infection compared to those with a light and moderate infection (8.7% versus 3.2%, p = 0.012) and compared to those without Schistosoma mansoni infection (8.7% versus 2.6%, p = 0.002). Further, we showed that some Salmonella isolates recovered from stool were very similar to isolates obtained from invasive infections (blood cultures from patients in a neighbouring hospital). [ABSTRACT FROM AUTHOR]