Abstract
Invasive non-typhoidal Salmonella infections have emerged as major health concern in sub-Saharan Africa, particularly affecting young children and individuals with HIV. This abstract summarizes keys findings from a thesis that investigated the characteristics and transmission dynamics of iNTS in the Democratic Republic of Congo.
Chapter 1 focused on the clinical presentation and impact of iNTS infections in children. The author conducted outreach visits to health zones experiencing outbreaks of severe febrile illness in children. The study found that iNTS infections were associated with high rates of admissions, Plasmodium falciparum malaria, blood transfusion, and case fatalities. The clinical picture of iNTS-infected children resembled severe malaria, with a high prevalence of parasite-confirmed Plasmodium falciparum malaria, severe anemia, and malnutrition. The main message from this chapter emphasized the importance of recognizing the combination of increased hospital admissions, blood transfusions, malaria and high case fatality as potential indicators of iNTS co-infection.
Chapter 2 investigated the role of rats as potential reservoir for iNTS. The study conducted live-capture trapping in marketplaces and abattoir in Kisangani. Rats, predominantly Rattus norvegicus, were captured at high rate and subset of these rats carried Salmonella. Molecular analysis revealed that some of the Salmonella Typhimurium isolates from rats belonged to sequence type (ST) 313, which is the main iNTS clade in sub-Saharan Africa. Interestingly, whole genome sequencing showed genetic relatedness between ST313 isolates from rats and human isolates, suggesting a potential transmission link. The study highlighted the possibility of environmental animals, particularly urban commensal rats, serving as reservoir for iNTS, with implications for control measures such as vaccination.
Chapter 3 examined household transmission of Salmonella among index patients with bloodstream infections. Stool samples from household members of index patients were cultured for Salmonella. The study found evidence of household clustering of iNTS, with matching Salmonella Typhimurium ST313 and Salmonella Enteritidis ST11 isolates detected in both blood and stool cultures. Results of whole genome sequencing revealed S. Typhimurium ST313 and S. Enteritidis ST 11 belonged to Lineage 2 and the Central/Eastern African clade, respectively and confirmed the relatedness of the MLVA-matching index patient -household clusters. The findings further indicated the potential persistence of iNTS in the intestinal tract for weeks after bloodstream infection.
Overall, this thesis provides important insights into the clinical characteristics, potential reservoirs, and household transmission dynamics of iNTS in sub-Saharan Africa. The findings underscore the need for targeted intervention to prevent and control iNTS infections, particularly in vulnerable populations such as young children and individuals with HIV.
Chapter 1 focused on the clinical presentation and impact of iNTS infections in children. The author conducted outreach visits to health zones experiencing outbreaks of severe febrile illness in children. The study found that iNTS infections were associated with high rates of admissions, Plasmodium falciparum malaria, blood transfusion, and case fatalities. The clinical picture of iNTS-infected children resembled severe malaria, with a high prevalence of parasite-confirmed Plasmodium falciparum malaria, severe anemia, and malnutrition. The main message from this chapter emphasized the importance of recognizing the combination of increased hospital admissions, blood transfusions, malaria and high case fatality as potential indicators of iNTS co-infection.
Chapter 2 investigated the role of rats as potential reservoir for iNTS. The study conducted live-capture trapping in marketplaces and abattoir in Kisangani. Rats, predominantly Rattus norvegicus, were captured at high rate and subset of these rats carried Salmonella. Molecular analysis revealed that some of the Salmonella Typhimurium isolates from rats belonged to sequence type (ST) 313, which is the main iNTS clade in sub-Saharan Africa. Interestingly, whole genome sequencing showed genetic relatedness between ST313 isolates from rats and human isolates, suggesting a potential transmission link. The study highlighted the possibility of environmental animals, particularly urban commensal rats, serving as reservoir for iNTS, with implications for control measures such as vaccination.
Chapter 3 examined household transmission of Salmonella among index patients with bloodstream infections. Stool samples from household members of index patients were cultured for Salmonella. The study found evidence of household clustering of iNTS, with matching Salmonella Typhimurium ST313 and Salmonella Enteritidis ST11 isolates detected in both blood and stool cultures. Results of whole genome sequencing revealed S. Typhimurium ST313 and S. Enteritidis ST 11 belonged to Lineage 2 and the Central/Eastern African clade, respectively and confirmed the relatedness of the MLVA-matching index patient -household clusters. The findings further indicated the potential persistence of iNTS in the intestinal tract for weeks after bloodstream infection.
Overall, this thesis provides important insights into the clinical characteristics, potential reservoirs, and household transmission dynamics of iNTS in sub-Saharan Africa. The findings underscore the need for targeted intervention to prevent and control iNTS infections, particularly in vulnerable populations such as young children and individuals with HIV.
| Translated title of the contribution | Studie van mogelijke reservoirs van invasieve non-typhi Salmonella in de Tshopo provincie, Democratische Republiek Congo |
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| Original language | English |
| Qualification | Doctor of Philosophy |
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| Supervisors/Advisors |
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| Award date | 15-Dec-2023 |
| Place of Publication | Leuven |
| Publisher | |
| Publication status | Published - 15-Dec-2023 |
Keywords
- B780-tropical-medicine