Geographical differences in tonsillar carriage rates of Fusobacterium necrophorum – A cross-sectional study in Sweden and Zambia

While Fusobacterium necrophorum historically has been considered normal tonsillar flora, recent studies from Europe and the US have suggested that carriage occur transiently in adolescence and young adulthood. However, no studies originating from Africa exist. In this cross-sectional study of tonsillar carriage of F. necrophorum, we aimed to investigate geographical differences in tonsillar carriage rates of F. necrophorum in healthy participants aged 15–25 years in Sweden and Zambia and further investigate the age distribution of tonsillar carriage in Zambia. Specimens were obtained by tonsillar swabs and analyzed with real-time PCR for F. necrophorum. In participants aged 15–25 years, tonsillar carriage was more common in Sweden 21/100 (21%) than in Zambia 6/192 (3%), p < 0.001. In Zambian participants aged above 25 years tonsillar carriage was rare 1/76 (1%). In conclusion, the high rate of tonsillar carriage in participants aged 15–25 years in Sweden has implications on the interpretation of tonsillar findings in patients with pharyngotonsillitis. Interestingly, a geographical difference was found with tonsillar carriage rarely identified in Zambia.