An Ongoing Diphtheria Epidemic in Guinea: Epidemiological and Microbiological Study from 2023 to 2025
Mamadou Bobo Diallo *
Université Gamal Abdel Nasser de Conakry, Chaire de Santé Publique, Conakry, Guinée, Institut National de Santé Publique (INSP), Kakoulimayah, Coyah, Guinée and Department of Public Health Laboratory, Guinea National Public Health Institute, Guinée.
Mohamed Prince Kaba
Institut National de Santé Publique (INSP), Kakoulimayah, Coyah, Guinée.
Sidiki Camara
Institut National de Santé Publique (INSP), Kakoulimayah, Coyah, Guinée and Department of Public Health Laboratory, Guinea National Public Health Institute, Guinée.
Ibrahima Gouressy
Institut National de Santé Publique (INSP), Kakoulimayah, Coyah, Guinée and Department of Public Health Laboratory, Guinea National Public Health Institute, Guinée.
Fatoumata Binta Baldé
Institut National de Santé Publique (INSP), Kakoulimayah, Coyah, Guinée and Department of Public Health Laboratory, Guinea National Public Health Institute, Guinée.
Sékouba Kourouma
Institut National de Santé Publique (INSP), Kakoulimayah, Coyah, Guinée and Department of Public Health Laboratory, Guinea National Public Health Institute, Guinée.
Lancinet Sangaré
Institut National de Santé Publique (INSP), Kakoulimayah, Coyah, Guinée and Department of Public Health Laboratory, Guinea National Public Health Institute, Guinée.
Boubane Benoit Thiara
Institut National de Santé Publique (INSP), Kakoulimayah, Coyah, Guinée and Department of Public Health Laboratory, Guinea National Public Health Institute, Guinée.
Célestin Guilavogui
Institut National de Santé Publique (INSP), Kakoulimayah, Coyah, Guinée.
Josué Delamou
Institut National de Santé Publique (INSP), Kakoulimayah, Coyah, Guinée and Department of Public Health Laboratory, Guinea National Public Health Institute, Guinée.
Aïcha Kessia Soumah
Institut National de Santé Publique (INSP), Kakoulimayah, Coyah, Guinée and Department of Public Health Laboratory, Guinea National Public Health Institute, Guinée.
Housseinatou Barry
Institut National de Santé Publique (INSP), Kakoulimayah, Coyah, Guinée and Department of Public Health Laboratory, Guinea National Public Health Institute, Guinée.
Kaba Kourouma
Université Gamal Abdel Nasser de Conakry, Chaire de Santé Publique, Conakry, Guinée, Institut National de Santé Publique (INSP), Kakoulimayah, Coyah, Guinée and Department of Public Health Laboratory, Guinea National Public Health Institute, Guinée.
Mahmoud Samah Cherif
Université Gamal Abdel Nasser de Conakry, Chaire de Santé Publique, Conakry, Guinée and Institut National de Santé Publique (INSP), Kakoulimayah, Coyah, Guinée.
Housseinatou Bah
Institut National de Santé Publique (INSP), Kakoulimayah, Coyah, Guinée.
Aboubacar Sidiki Magassouba
Université Gamal Abdel Nasser de Conakry, Chaire de Santé Publique, Conakry, Guinée.
*Author to whom correspondence should be addressed.
Abstract
Objectives: This study describes the epidemiological and microbiological characteristics of Corynebacterium species cases between 2023 and 2025, to guide surveillance, prevention, and management.
Study type: A descriptive cross-sectional study was conducted in six affected health regions.
Study location and duration: All oropharyngeal or nasopharyngeal swabs meeting WHO definitions of suspected cases were centralized at the bacteriology laboratory of the National Institute of Public Health between 2023 and 2025
Methods: Bacterial identification was performed by culture on selective media (potassium tellurite agar 3.5% and Colombian agar with 5% sheep blood) and using the Corne API, and antibiotic susceptibility testing (using disk diffusion method on Mueller-Hinton agar enriched with horse blood) was interpreted according to CA-SFM/EUCAST 2023 standards.
Results: Of 997 samples received, 914 were included. The median age of the patients was 7 years (IQR: 3–15 years), with a predominance of children aged 0–4 years (33.9%). The Kankan region accounted for 68.4% of reported cases. Culture was positive in 17.9% of cases (n = 164). Corynebacterium diphtheriae biovar mitis was the predominant strain (80.5%), followed by C. pseudodiphtheriticum (12.8%) and C. diphtheriae biovar gravis (6.1%). The C. diphtheriae strains showed complete susceptibility to erythromycin but high resistance to β-lactams and tetracyclines. Only one death was reported (case fatality rate of 0.1%).
Conclusion: The diphtheria epidemic in Guinea is characterized by persistent transmission, primarily affecting young children, with a high geographic concentration. The results support the use of macrolides as first-line therapy, the restriction of tetracyclines and cotrimoxazole, and highlight the need to strengthen childhood vaccination and microbiological surveillance.
Keywords: Diphtheria, corynebacterium diphtheriae, epidemic, Guinea, antibiogram, vaccination