Poster Presentation Lancefield International Symposium for Streptococci and Streptococcal Diseases 2025

Streptococcus dysgalactiae subsp. equisimilis carriage and infection epidemiology and risk factors in The Gambia  (#69)

Edwin Armitage 1 2 , Gabrielle De Crombrugghe 3 , Alexander J Keeley 1 4 , Elina Senghore 1 , Fatoumata E Camara 1 , Musukoi Jammeh 1 , Thushan de Silva 5 , Michael Marks 4
  1. MRCG @ LSHTM, Fajara, The Gambia, N/A, Gambia
  2. Population Heatlh Sciences, University of Bristol, Bristol, United Kingdom
  3. Molecular Bacteriology Laboratory, European Plotkin Institute for Vaccinology, Brussels, Belgium
  4. Clinical Research Department, London School of Hygiene and Tropical Medicione, London, UK
  5. Department of Infection, The University of Sheffield, Sheffield, UK

Background 

Streptococcus dysgalactiae subsp. equisimilis (SDSE) is an under-recognised pathogen responsible for an increasing amount of invasive and necrotising soft tissue infections, as well as pharyngeal carriage and infections particularly in high Rheumatic Heart Disease (RHD) burden regions. The epidemiology of SDSE pharyngeal carriage and infection in Africa is unknown.  

Methods 

SpyCATS, a 13-month prospective household cohort study, recruited 442 participants from 44 households in The Gambia. Monthly oropharyngeal and skin swabs were collected for SDSE culture. Incident cases of pharyngitis and pyoderma were swabbed. Socio-demographic and household contact data were captured. 

Results 

SDSE pharyngeal carriage was common, with 130 episodes occurring in 94 individuals at an incidence of 358/1000 person-years (pyrs). Pharyngitis incidence was 51/1000pyrs. Median pharyngeal clearance time was 10.5 days. Skin carriage and pyoderma rates were low. Pharyngeal carriage and pharyngitis risk was elevated with increasing household size (HR 1.03, 95% CI 1.01-1.04, p<0.001 and HR 1.04, 95% CI 1.02-1.07, p=0.001 respectively). Sharing a bed with someone with SDSE pharyngitis increased the risk of pharyngeal carriage (HR 4.34, 95% CI1.26-15.0, p=0.020), as did sharing a bedroom with another carrier (HR 2.11, 95% CI 1.24-3.57, p=0.006). 

Conclusions 

SDSE is an important pathogen in this setting, causing as much pharyngitis as Streptococcus pyogenes (Strep A). SDSE pharyngeal carriage incidence is higher than Strep A, persists for longer and can lead to transmission to household contacts. Improved surveillance and detection methods are required to better understand the burden of SDSE and its relationship to Strep A in high-RHD settings.