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

PLoS Negl Trop Dis. 2020 Feb 21;14(2):e0007875. doi: 10.1371/journal.pntd.0007875. eCollection 2020 Feb.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Animals
  • Carrier State / epidemiology
  • Carrier State / microbiology*
  • Child
  • Coinfection / epidemiology
  • Coinfection / microbiology
  • Coinfection / parasitology
  • Cross-Sectional Studies
  • Democratic Republic of the Congo / epidemiology
  • Female
  • Humans
  • Intestines / microbiology*
  • Male
  • Rural Population
  • Salmonella typhimurium / genetics
  • Salmonella typhimurium / isolation & purification*
  • Schistosoma mansoni / genetics
  • Schistosoma mansoni / isolation & purification
  • Schistosoma mansoni / physiology
  • Schistosomiasis mansoni / epidemiology
  • Schistosomiasis mansoni / parasitology*
  • Young Adult

Grants and funding

This work was funded by the Belgian Directorate of Development Cooperation (DGD) through the 3rd and 4th Framework Agreement between the Institute of Tropical Medicine in Belgium, Antwerp, Belgium and the National Institute for Biomedical Research, Kinshasa, Democratic Republic of the Congo as well as by the Baillet-Latour Fund. LK holds a PhD scholarship from the Belgian DGD and ASH holds a PhD scholarship from the Research Foundation Flanders. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.