Prevalence of diphtheria and antimicrobial-resistant wound infections among asylum seekers in Heidelberg, Germany, August–October 2024

PURPOSE: In the second half of 2022 and 2023, an increase of diphtheria cases among asylum seekers was observed in Europe, with 120 cases reported in the state of Baden-Wuerttemberg, Germany. We aimed to determine prevalence of infection or colonization with toxigenic Corynebacterium among asylum seekers arriving between August and October 2024 in Heidelberg, Germany. In addition, we assessed antimicrobial-resistant wound infections and diphtheria immunity levels in this population. METHODS: We conducted a cross-sectional study with a random sample of 1073 newly arrived asylum seekers. Consenting participants received a throat and, if applicable, wound swabs. Demographic, clinical and migration-related information was collected to identify potential risk groups. Throat swabs were tested for toxigenic Corynebacterium species, while wound swabs were additionally tested for other antimicrobial-resistant pathogens with relevance to therapeutic management. IgG antibody levels against diphtheria toxoid were quantified in serum samples of a random sub-sample. RESULTS: Of the participants, 75% were male (n = 804), and ages ranged from 15 to 60 years (median = 27 years). The most common nationalities were Syrian (n = 281), Turkish (n = 189) and Afghan (n = 117). No toxigenic Corynebacterium was identified. Thirty-seven participants carried inflamed wounds, of whom 18 (49%) had wounds infected with methicillin-resistant Staphylococcus aureus (MRSA), corresponding to 1.7% (95% CI 1.0-2.6%) of the entire study population. Overall, 38.0% (95% CI 33.3-44.8%) showed non-protective diphtheria antibody titers, while acceptance of the on-site diphtheria vaccination was high at 93% (n = 998). CONCLUSION: While no toxigenic Corynebacterium was detected, low immunity levels and antimicrobial resistance findings underline the importance of early diagnosis, treatment and vaccination options in displaced populations.