Direct association between rainfall and non-typhoidal Salmonella bloodstream infections in hospital-admitted children in the Democratic Republic of Congo

Tack, Bieke; Vita, Daniel; Phoba, Marie-France; Mbuyi-Kalonji, Lisette; Hardy, Liselotte; Barbé, Barbara; Jacobs, Jan; Lunguya, Octavie; Jacobs, Liesbet

doi:10.1038/s41598-021-01030-x

Cited by 17 publications

(21 citation statements)

References 51 publications

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“…Other non-typhoidal Salmonella serotypes were observed in the meat pathway too, but not ST313 [23]. Furthermore, a study in DR Congo showed a direct association of rainfall with iNTS, pointing to a possible waterborne environmental reservoir [69].…”

Section: The Present Findings Point To the Evidence Of An Animal Rese...mentioning

confidence: 91%

“…Apart from rats, small rodents such as mice should be assessed, as well as lizards and geckos which are notable carriers of Salmonella too [77]. Food and water should be further assessed as a vehicle for transmission, including fork-to-farm studies along the meat pathway [23,78], crops and green leaves [13,69]. Source attribution studies such as case-control and outbreak investigation studies should complement the picture of iNTS transmission [13,78].…”

Section: Limitations and Strengthsmentioning

confidence: 99%

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Urban rats as carriers of invasive Salmonella Typhimurium sequence type 313, Kisangani, Democratic Republic of Congo

Falay

Hardy²,

Tanzito³

et al. 2022

PLoS Negl Trop Dis

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Background Invasive non-typhoidal Salmonella (iNTS–mainly serotypes Enteritidis and Typhimurium) are major causes of bloodstream infections in children in sub-Saharan Africa, but their reservoir remains unknown. We assessed iNTS carriage in rats in an urban setting endemic for iNTS carriage and compared genetic profiles of iNTS from rats with those isolated from humans. Methodology/Principal findings From April 2016 to December 2018, rats were trapped in five marketplaces and a slaughterhouse in Kisangani, Democratic Republic of the Congo. After euthanasia, blood, liver, spleen, and rectal content were cultured for Salmonella. Genetic relatedness between iNTS from rats and humans—obtained from blood cultures at Kisangani University Hospital—was assessed with multilocus variable-number tandem repeat (VNTR) analysis (MLVA), multilocus sequence typing (MLST) and core-genome MLST (cgMLST). 1650 live-capture traps yielded 566 (34.3%) rats (95.6% Rattus norvegicus, 4.4% Rattus rattus); 46 (8.1%) of them carried Salmonella, of which 13 had more than one serotype. The most common serotypes were II.42:r:- (n = 18 rats), Kapemba (n = 12), Weltevreden and Typhimurium (n = 10, each), and Dublin (n = 8). Salmonella Typhimurium belonged to MLST ST19 (n = 7 rats) and the invasive ST313 (n = 3, isolated from deep organs but not from rectal content). Sixteen human S. Typhimurium isolates (all ST313) were available for comparison: MLVA and cgMLST revealed two distinct rat-human clusters involving both six human isolates, respectively, i.e. in total 12/16 human ST313 isolates. All ST313 Typhimurium isolates from rats and humans clustered with the ST313 Lineage 2 isolates and most were multidrug resistant; the remaining isolates from rats including S. Typhimurium ST19 were pan-susceptible.s1 Conclusion The present study provides evidence of urban rats as potential reservoirs of S. Typhimurium ST313 in an iNTS endemic area in sub-Saharan Africa.

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Section: The Present Findings Point To the Evidence Of An Animal Rese...mentioning

confidence: 91%

Section: Limitations and Strengthsmentioning

confidence: 99%

Urban rats as carriers of invasive Salmonella Typhimurium sequence type 313, Kisangani, Democratic Republic of Congo

Falay

Hardy²,

Tanzito³

et al. 2022

PLoS Negl Trop Dis

Self Cite

View full text Add to dashboard Cite

show abstract

“…The reservoirs and transmission route of the pathogens responsible for iNTS in SSA remains unknown. Seasonal patterns of iNTS, and the close domestic association of humans and animals in parts of SSA might suggest that environmental factors could play a role [ 34 , 35 ]. However, numerous studies have failed to establish any convincing link between strains causing invasive disease, with domestic or household animals or with meat-production.…”

Section: Discussionmentioning

confidence: 99%

Case-control investigation of invasive Salmonella disease in Malawi reveals no evidence of environmental or animal transmission of invasive strains, and supports human to human transmission

Koolman

Prakash²,

Diness³

et al. 2022

PLoS Negl Trop Dis

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Background Invasive Salmonella infections cause significant morbidity and mortality in Sub-Saharan Africa. However, the routes of transmission are uncertain. We conducted a case-control study of index-case and geographically-matched control households in Blantyre, Malawi, sampling Salmonella isolates from index cases, healthy people, animals, and the household environment. Methodology Sixty index cases of human invasive Salmonella infection were recruited (March 2015-Oct 2016). Twenty-eight invasive Non-Typhoidal Salmonella (iNTS) disease and 32 typhoid patients consented to household sampling. Each index-case household was geographically matched to a control household. Extensive microbiological sampling included stool sampling from healthy household members, stool or rectal swabs from household-associated animals and boot-sock sampling of the household environment. Findings 1203 samples from 120 households, yielded 43 non-Typhoidal Salmonella (NTS) isolates from 25 households (overall sample positivity 3.6%). In the 28 iNTS patients, disease was caused by 3 STs of Salmonella Typhimurium, mainly ST313. In contrast, the isolates from households spanned 15 sequence types (STs). Two S. Typhimurium isolates from index cases closely matched isolates from their respective asymptomatic household members (2 and 3 SNP differences respectively). Despite the recovery of a diverse range of NTS, there was no overlap between the STs causing iNTS disease with any environmental or animal isolates. Conclusions The finding of NTS strains from index cases that matched household members, coupled with lack of related animal or environmental isolates, supports a hypothesis of human to human transmission of iNTS infections in the household. The breadth of NTS strains found in animals and the household environment demonstrated the robustness of NTS sampling and culture methodology, and suggests a diverse ecology of Salmonella in this setting. Healthy typhoid (S. Typhi) carrier state was not detected. The lack of S. Typhi isolates from the household environment suggests that further methodological development is needed to culture S. Typhi from the environment.

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“…While NTS infection in HICs is generally associated with zoonotic transmission, the reservoirs and transmission route of the pathogens responsible for iNTS in SSA remains unknown. Seasonal patterns of iNTS, and the close domestic association of humans and animals in parts of SSA suggest that environmental factors could play a role [28,29]. Serotypes associated with iNTS have been isolated from animals in South Africa, although no genetic characterisation was carried out on these samples [30,31].…”

Section: Introductionmentioning

confidence: 99%

“…Seasonal patterns of iNTS, and the close domestic association of humans and animals in parts of SSA suggest a possible role for environmental factors [25,26]. Serotypes associated with iNTS have been isolated from animals in South Africa, although no genetic characterisation was carried out on these samples [27,28].…”

Section: Introductionmentioning

confidence: 99%

Case-control investigation of invasive Salmonella disease in Malawi reveals no evidence of environmental or animal transmission of invasive strains, and supports human to human transmission

Koolman

Prakash

Diness

et al. 2022

Preprint

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Background Invasive Salmonella infections are a major cause of morbidity and mortality in Sub-Saharan Africa (SSA), but the sources and transmission routes are uncertain. We investigated potential sources for cases of invasive disease by sampling healthy people, animals, and the environment in index-case and geographically-matched control households. Methods Sixty index cases of human invasive Salmonella infection were recruited (28 invasive Non-Typhoidal Salmonella (iNTS) disease, and 32 typhoid). Each index-case household was geographically matched to a control household. Extensive microbiological sampling included stool sampling from healthy household members, stool or rectal swabs from household-associated animals and boot-sock sampling of the household environment. Results 1203 samples were taken from 120 households, yielding 43 Salmonella isolates from 25 households (overall sample positivity 3.6%). Isolates from households were all NTS and spanned 15 STs. iNTS disease was caused by 3 STs of Salmonella Typhimurium, mainly ST313. Two S. Typhimurium isolates from index cases closely matched isolates from their respective asymptomatic household members (2 and 3 SNPs different respectively). There was no overlap of STs causing iNTS disease with environmental or animal isolates, despite recovery of diverse NTS. Conclusions The finding of NTS strains from index cases matching household members, coupled with lack of overlap with either animal or environmental isolates, supports a hypothesis that healthy humans are the source of iNTS infections in the household. The breadth of NTS strains found in the household environment across all sites demonstrated the robustness of sampling and methodology to detect NTS, and suggests a diverse ecology of Salmonella in this setting. The lack of S. Typhi isolated from the household environment may suggest a need for further methodological development to culture sources of typhoid.

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Direct association between rainfall and non-typhoidal Salmonella bloodstream infections in hospital-admitted children in the Democratic Republic of Congo

Cited by 17 publications

References 51 publications

Urban rats as carriers of invasive Salmonella Typhimurium sequence type 313, Kisangani, Democratic Republic of Congo

Urban rats as carriers of invasive Salmonella Typhimurium sequence type 313, Kisangani, Democratic Republic of Congo

Case-control investigation of invasive Salmonella disease in Malawi reveals no evidence of environmental or animal transmission of invasive strains, and supports human to human transmission

Case-control investigation of invasive Salmonella disease in Malawi reveals no evidence of environmental or animal transmission of invasive strains, and supports human to human transmission

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