Mbuyi LK1,2, Barbé B3, Madinga J5,6,8, Roucher C5, Linsuke S6,7, Hermy M5, Baloji S6, Anne-Sophie Heroes³, Nkoji G², Katja Polman5, Lutumba P5,6,7, Phoba MF1,2, Lunguya O1,2, Jan Jacobs3,4.


1 Department of Clinical Microbiology, National Institute for Biomedical Research; Democratic Republic of the Congo

2 Service of Microbiology, University Hospital of Kinshasa, Democratic Republic of the Congo

3 Department of Clinical Sciences, Institute of Tropical Medicine, Antwerp, Belgium

4 Microbiology and Immunology, KU Leuven, Belgium

5 Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium

6 Department of Epidemiology, National Institute for Biomedical Research; Democratic Republic of the Congo

7 Department of Tropical Medicine, University Hospital of Kinshasa, Democratic Republic of the Congo

8 Institute of Health and Society, Université Catholique de Louvain, Brussels, Belgium

Summary

Background. In Sub-Saharan Africa, Schistosoma infection is mentioned as a risk factor for Salmonella carriage. We assessed the co-presence of intestinal Salmonella and Schistosoma in a rural site in the Democratic Republic of the Congo (DRC, Kifua II village, Kongo Central Province), endemic for Schistosoma infection and invasive salmonellosis.

Methods. From November 2015 to March 2016 (during the rainy season), healthy inhabitants aged ≥ 1 year were asked to give two consecutive stool samples after informed consent. Samples were assessed for Salmonella (culture with Selenite broth and Salmonella-Shigella agar) and Schistosoma eggs (microscopy, Kato Katz).

Results. Overall, 2.007 stool samples were collected from 1.108 participants (representing 88.6% of the population n= 1,250); median age (interquartile range (IQR)) was 15 (7-35) years. Half of participants (n = 567; 51.2%) were Schistosoma mansoni positive. Schistosoma egg load was light in 51% (n = 291), moderate in 31% (n = 173) and heavy in 18% (n= 103) of Schistosoma-infected participants. A total of 40 (3.6%) participants were found carriers of non-typhoidal Salmonella; none of the samples grew Salmonella typhi. Mean age ± standard deviation of Salmonella carriers was 25 ± 19 years and did not differ from the non-Salmonella infected participants (22 ± 19 years, p = 0.32); male-to-female rates were 1:1.5 and 1:1.1 respectively (p = 0.37). Salmonella was isolated in similar proportions among Schistosoma-infected and non-infected participants (4.4% (25/567) and 2.8% (15/541) respectively, p = 0.14). Egg loads among Salmonella-Schistosoma co-infected participants were mostly light (n = 12; 48%) and heavy (n = 9; 36%). Follow-up of 17 Salmonella carriers revealed a single participant with repeat culture for Salmonella, 4 weeks after the initial sampling.

Conclusions. The present study, conducted in a rural area in DRC showed (i) Salmonella intestinal carriage rates of 3.6% which were (ii) not associated with Schistosoma mansoni intestinal infection.

Keywords: carriage rates, coinfection Salmonella – Schistosoma, DR Congo