Population-based incidence, seasonality and serotype distribution of invasive salmonellosis among children in Nanoro, rural Burkina Faso

PLoS One. 2017 Jul 10;12(7):e0178577. doi: 10.1371/journal.pone.0178577. eCollection 2017.

Abstract

Background: Bloodstream infections (BSI) caused by Salmonella Typhi and invasive non-Typhoidal Salmonella (iNTS) frequently affect children living in rural sub-Saharan Africa but data about incidence and serotype distribution are rare.

Objective: The present study assessed the population-based incidence of Salmonella BSI and severe malaria in a Health and Demographic Surveillance System in a rural area with seasonal malaria transmission in Nanoro, Burkina Faso.

Methods: Children between 2 months-15 years old with severe febrile illness were enrolled during a one-year surveillance period (May 2013-May 2014). Thick blood films and blood cultures were sampled and processed upon admission. Population-based incidences were corrected for non-referral, health seeking behavior, non-inclusion and blood culture sensitivity. Adjusted incidence rates were expressed per 100,000 person-years of observations (PYO).

Results: Among children < 5 years old, incidence rates for iNTS, Salmonella Typhi and severe malaria per 100,000 PYO were 4,138 (95% Confidence Interval (CI): 3,740-4,572), 224 (95% CI: 138-340) and 2,866 (95% CI: 2,538-3,233) respectively. Among those aged 5-15 years, corresponding incidence rates were 25 (95% CI: 8-60), 273 (95% CI: 203-355) and 135 (95% CI: 87-195) respectively. Most iNTS occurred during the peak of the rainy season and in parallel with the increase of Plasmodium falciparum malaria; for Salmonella Typhi no clear seasonal pattern was observed. Salmonella Typhi and iNTS accounted for 13.3% and 55.8% of all 118 BSI episodes; 71.6% of iNTS (48/67) isolates were Salmonella enterica serovar Typhimurium and 25.4% (17/67) Salmonella enterica serovar Enteritidis; there was no apparent geographical clustering.

Conclusion: The present findings from rural West-Africa confirm high incidences of Salmonella Typhi and iNTS, the latter with a seasonal and Plasmodium falciparum-related pattern. It urges prioritization of the development and implementation of Salmonella Typhi as well as iNTS vaccines in this setting.

MeSH terms

  • Burkina Faso / epidemiology
  • Catchment Area, Health
  • Child
  • Child, Preschool
  • Demography
  • Female
  • Geography
  • Humans
  • Incidence
  • Infant
  • Malaria / complications
  • Malaria / epidemiology
  • Male
  • Salmonella / isolation & purification
  • Salmonella Infections / blood*
  • Salmonella Infections / epidemiology*
  • Seasons
  • Serotyping / methods*

Grants and funding

This project was funded by the Projects Network Laboratory Quality Management (Nr. 126) and Clinical Research (128) of the Third Framework Agreement between the Belgian DGD (Ministry of Development Cooperation) and the Institute of Tropical Medicine (ITM), Belgium. (website: http://diplomatie.belgium.be/en/policy/development_cooperation/work_with_us/financing_opportunities/study_and_training_grants). The work of JM was partly funded by ‘‘Steunfonds Margeurite-Marie Delacroix’’ (No grant number available, website http://www.fondsmmdelacroix.org/nl/nos-activites/bourses-de-recherche/). For this study JM received additional grants from the Fund for Scientific Research-Flanders (F.W.O.-Vlaanderen, Belgium. Grant number V453812N, website http://www.fwo.be/en/) and the Junior Mobility program of KU Leuven (grant JUMO/12/008, website https://www.kuleuven.be/personeel/careercenter/youreca-career-center/yourecaENG/youreca-internationalmobility). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.