Publication by our researchers on the risk of Lyme borreliosis after a tick bite in Poland

29 01 2026

Researchers from the Department of Parasitology (Institute of Experimental Zoology, Faculty of Biology, University of Warsaw), MSc Julia Koczwarska and Dr hab. Renata Welc-Falęciak, have published the results of a study on the risk of developing Lyme borreliosis after a bite by the common tick Ixodes ricinus in Poland, and on the factors that increase this risk. The paper, titled “Incidence of Lyme borreliosis following Ixodes ricinus tick bites in Poland: a citizen science approach”, was published in Parasites & Vectors.

Lyme borreliosis, caused by bacteria of the genus Borrelia, is one of the most common tick-borne diseases in Europe, and its reported incidence is also increasing in Poland. The risk of infection after a tick bite depends on several factors, including whether the tick is infected, how long it has been feeding, and the tick’s developmental stage. Nymphs are particularly important from a public health perspective because they are very small and therefore easy to miss on the body.

The study used a citizen science approach. People who had been bitten by ticks submitted the removed ticks for laboratory testing and completed questionnaires describing follow-up observations after the bite. This design made it possible to link clinical information with molecular test results obtained from the ticks.

The authors found that the overall risk of developing Lyme borreliosis after a bite by Ixodes ricinus was 3.1%, which corresponds to 54 clinically confirmed cases among 1,757 people with complete data. Borrelia spp. were detected in 15.7% of the examined ticks, with a total of 2,079 specimens analysed. Infection was more frequent in adult ticks than in nymphs, and the prevalence of Borrelia spp. was lower in 2022 than in 2021.

The most important factor increasing risk was whether the tick carried Borrelia DNA. When Borrelia DNA was detected, the risk of Lyme borreliosis increased to 16.0%, whereas it was 0.5% after a bite by a tick that tested negative (including situations where the bacterial load may have been too low to detect). Among infected ticks, risk rose with feeding time and reached 30% after more than 48 hours, compared with 10% when the tick was removed within the first 24 hours. Erythema migrans was reported by 1.9% of all participants and by 64.9% of those diagnosed with Lyme borreliosis. Among ticks removed from people who developed the disease, the predominant species was ** Borrelia afzelii **. The authors also highlighted ** Borrelia miyamotoi **, which showed a higher bacterial load in ticks than species from the Borrelia burgdorferi sensu lato complex, suggesting that this pathogen should also be considered in tick-borne disease risk assessment in Poland.

The publication is available at:
https://link.springer.com/article/10.1186/s13071-025-07133-y

We warmly congratulate the Authors on their publication and invite you to explore educational materials on the Kleszczologia website, where you can find information about ticks, as well as recommendations on how to protect yourself and what to do after a tick bite:
https://kleszczologia.biol.uw.edu.pl/