Incidence of invasive salmonella disease in sub-Saharan Africa: a multicentre population-based surveillance study

Abstract

SummaryBackgroundAvailable incidence data for invasive salmonella disease in sub-Saharan Africa are scarce. Standardised, multicountry data are required to better understand the nature and burden of disease in Africa. We aimed to measure the adjusted incidence estimates of typhoid fever and invasive non-typhoidal salmonella (iNTS) disease in sub-Saharan Africa, and the antimicrobial susceptibility profiles of the causative agents.MethodsWe established a systematic, standardised surveillance of blood culture-based febrile illness in 13 African sentinel sites with previous reports of typhoid fever: Burkina Faso (two sites), Ethiopia, Ghana, Guinea-Bissau, Kenya, Madagascar (two sites), Senegal, South Africa, Sudan, and Tanzania (two sites). We used census data and health-care records to define study catchment areas and populations. Eligible participants were either inpatients or outpatients who resided within the catchment area and presented with tympanic (≥38·0°C) or axillary temperature (≥37·5°C). Inpatients with a reported history of fever for 72 h or longer were excluded. We also implemented a health-care utilisation survey in a sample of households randomly selected from each study area to investigate health-seeking behaviour in cases of self-reported fever lasting less than 3 days. Typhoid fever and iNTS disease incidences were corrected for health-care-seeking behaviour and recruitment.FindingsBetween March 1, 2010, and Jan 31, 2014, 135 Salmonella enterica serotype Typhi (S Typhi) and 94 iNTS isolates were cultured from the blood of 13 431 febrile patients. Salmonella spp accounted for 33% or more of all bacterial pathogens at nine sites. The adjusted incidence rate (AIR) of S Typhi per 100 000 person-years of observation ranged from 0 (95% CI 0–0) in Sudan to 383 (274–535) at one site in Burkina Faso; the AIR of iNTS ranged from 0 in Sudan, Ethiopia, Madagascar (Isotry site), and South Africa to 237 (178–316) at the second site in Burkina Faso. The AIR of iNTS and typhoid fever in individuals younger than 15 years old was typically higher than in those aged 15 years or older. Multidrug-resistant S Typhi was isolated in Ghana, Kenya, and Tanzania (both sites combined), and multidrug-resistant iNTS was isolated in Burkina Faso (both sites combined), Ghana, Kenya, and Guinea-Bissau.InterpretationTyphoid fever and iNTS disease are major causes of invasive bacterial febrile illness in the sampled locations, most commonly affecting children in both low and high population density settings. The development of iNTS vaccines and the introduction of S Typhi conjugate vaccines should be considered for high-incidence settings, such as those identified in this study.FundingBill & Melinda Gates Foundation.

Modeling and Cost Benefit Analysis to Guide Deployment of POC Diagnostics for Non-typhoidalSalmonellaInfections with Antimicrobial Resistance

“…However, further studies and data would be needed to parameterize such a detailed model. NTS responds strongly to co-morbidities and risk factors such as HIV, malnutrition, malaria infection, and anemia, as well as rural settings and age 3,5 . It would therefore be interesting to consider how addressing these co-morbidites and risk factors (i.e.…”

“…The manifestation of NTS infection can vary considerably from mild gastroenteritis to sepsis. Manifestation of NTS infection is divided into invasive and non-invasive disease, of which the former is responsible for approximately 3.4 million illnesses and over 600,000 deaths annually world-wide 2,3 . Microbiologically treated invasive NTS disease can have a case fatality rate of 20-47% in African adults and children, and accounts for around 39% of community-acquired blood stream infections in sub-Saharan Africa [4][5][6] .…”

Typhoid conjugate vaccines: making vaccine history in Africa

“…A systematic review including seven studies estimated a total number of 3,090,395 cases in Africa per year with 33,490 deaths [2]. Since this publication, the Typhoid Surveillance in Africa Program (TSAP), a large multisite study, performed surveillance across 10 countries, in 13 sites, with incidence estimates ranging from 0 up to 383 cases per 100,000 person-years observation [8]. What is very clear is the significant spatial and temporal heterogeneity of typhoid burden in Africa.…”

Pattern of Antibody Titer Against Salmonella Enterica in Apparently Healthy Individuals

“…In Nepal, the laboratory facilities for blood culture for the confirmation of typhoid fever are not available in district laboratories and below district level health care centers, hence the serological test using the Widal test is done only in few hospitals, private clinics and primary health care centers 16,12 . The diagnosis is made on the basis of findings of Widal test 17 .…”