A Systematic Review of the Incidence, Risk Factors and Case Fatality Rates of Invasive Nontyphoidal Salmonella (iNTS) Disease in Africa (1966 to 2014)

Abstract

This study systematically reviews the literature on the occurrence, incidence and case fatality rate (CFR) of invasive nontyphoidal Salmonella (iNTS) disease in Africa from 1966 to 2014. Data on the burden of iNTS disease in Africa are sparse and generally have not been aggregated, making it difficult to describe the epidemiology that is needed to inform the development and implementation of effective prevention and control policies. This study involved a comprehensive search of PubMed and Embase databases. It documents the geographical spread of iNTS disease over time in Africa, and describes its reported incidence, risk factors and CFR. We found that Nontyphoidal Salmonella (NTS) have been reported as a cause of bacteraemia in 33 out of 54 African countries, spanning the five geographical regions of Africa, and especially in sub-Saharan Africa since 1966. Our review indicates that NTS have been responsible for up to 39% of community acquired blood stream infections in sub-Saharan Africa with an average CFR of 19%. Salmonella Typhimurium and Enteritidis are the major serovars implicated and together have been responsible for 91%% of the cases of iNTS disease, (where serotype was determined), reported in Africa. The study confirms that iNTS disease is more prevalent amongst Human Immunodeficiency Virus (HIV)-infected individuals, infants, and young children with malaria, anaemia and malnutrition. In conclusion, iNTS disease is a substantial cause of community-acquired bacteraemia in Africa. Given the high morbidity and mortality of iNTS disease in Africa, it is important to develop effective prevention and control strategies including vaccination.

Correlates of non-typhoidal Salmonella bacteraemia: A case–control study

“…These findings support the present study observations. The correlates of NTS bacteraemia identified in this study, and reports from developed countries, differ from those found in Sub-Saharan Africa, where HIV, young age, malaria, anaemia, and malnutrition are the main risk factors (Uche et al, 2017). Interestingly, a positive association was found between chronic/ paroxysmal atrial fibrillation and NTS bacteraemia when compared to salmonellosis patients and when compared to patients with bacteraemia due to other pathogens.…”

Prioritising pathogens for the management of severe febrile patients to improve clinical care in low- and middle-income countries

“…3 Percentage of agreement between the overall pathogen ranking for the SFWS use case and subpopulations and different regions stakeholders with a predominant focus on Africa might have underestimated their relevance at a global level. Typhoidal and non-typhoidal Salmonella (NTS) were both moved to the top of the list based on stakeholder feedback, which reflects the current attention on the global agenda, especially for NTS as a co-infection with malaria and HIV [41]. With the emergence of substantial drug resistance in S. Typhi, good surveillance data to support interventions with the available typhoid vaccine as well as treatment strategies are crucial.…”

Salmonella infection: Interplay between the bacteria and host immune system

“…One indication that CD4 T cells are essential mediators of immunity against NTS infection in humans comes from the finding that normally non-invasive NTS can cause a severe, invasive, systemic infection (iNTS) in HIV-infected individuals, where CD4 T cells are naturally depleted [94]. In fact, antiretroviral HIV therapy has been shown to decrease the incidence of iNTS infection in humans, demonstrating that CD4 T cells are among the most important immune cells mediating immunity against salmonellosis [95].…”