In Finland, a National Infectious Disease Register was established in 1994, which contains information about laboratory confirmed findings of infectious diseases. For the present study, monthly numbers of zoonotic infections in children from January 1996 to December 2019 have been analyzed for infections caused by Borrelia burgdorferi, Puumala virus, Francisella tularensis and TBE virus.
Overall, a total of 6107 laboratory-confirmed zoonotic findings were reported for patients aged 0–19 years during the years 1996–2019. 54% of the cases were B. burgdorferi, 31% were Puumala virus, 12% were F. tularensis and 2% were TBE cases. TBE was mainly detected from May to November.
Incidences for B. burgdorferi and TBE virus have increased in Finland among patients aged 0–19 years over the past 24 years with a total of 129 TBE cases reported. Of these cases, 11% were in the age group 0–4 years, 44% in patients 5–9 years, 29% in patients 10–14 years and 16% in patients 15–19 years. The highest yearly incidence of TBE (0.9 per 100,000) occurred in 2019, and the incidence of TBE appeared to exhibit an increasing trend. TBE cases were mostly reported from southwestern Finland with a trend to northward expansion during the period 1996–2019, and the highest regional incidence was reported in the Åland Islands (22 per 100,000 person-years).