Differential Exposure to Borrelia spp. and Spotted Fever Group Rickettsia in Serbia and North Macedonia: A Comparative Study

Dejan Jakimovski, Sofija Mateska, Marija Najdovska, Angela Stamenkovska, Verica Pavleva, Mile Bosilkovski, Dragana Mijatović, Verica Simin, Ivana Bogdan, Jasmina Grujić, Milica Simeunović, Miodrag Vranješ, Eleftherios Meletis, Polychronis Kostoulas, Olympia Lioupi and Pavle Banović

Skopje, North Macedonia / Novi Sad, Serbia – August 2025 – A recent cross-border study highlights stark differences in exposure to tick-borne pathogens between neighboring Balkan countries. Researchers from Serbia and North Macedonia found that residents in Skopje showed significantly higher exposure to spotted fever group Rickettsia (SFGR), while individuals in Novi Sad were more frequently exposed to Borrelia species, the bacteria responsible for Lyme disease.

The study, published in Pathogens, analyzed blood samples from 223 participants, including individuals recently bitten by ticks and healthy controls. In Skopje, nearly one-third of tick-exposed participants (30.9%) tested positive for SFGR antibodies, a rate almost four times higher than in Novi Sad (8.0%). Conversely, anti-Borrelia antibodies were more commonly detected in Novi Sad, though differences were not statistically significant.

“Our findings suggest a north-to-south gradient in tick-borne pathogen exposure across the Balkans,” said lead author Dejan Jakimovski. “Borrelia exposure is higher in northern regions like Novi Sad, while SFGR exposure dominates in the south, particularly in Skopje.”

The research underscores the under-recognition of SFGR infections in North Macedonia, where high exposure rates contrast with limited clinical reporting. In both countries, the study authors stress the urgent need for enhanced surveillance, diagnostic capacity, and public health infrastructure to better identify and manage tick-borne diseases.

The study also highlighted dual exposure, with some individuals showing antibodies for both pathogens, emphasizing the complexity of tick-borne disease ecology in the region.

“Tick-borne rickettsioses may be circulating undetected due to mild or atypical symptoms,” said Pavle Banović, co-author and coordinator. “Public health authorities must establish targeted surveillance and early diagnostic protocols to prevent serious complications.”

The research draws attention to the need for multicenter studies to map risk zones for Lyme disease and SFGR and to implement region-specific public health strategies.

The study was conducted under ethical approval from the faculties of medicine in Skopje and Novi Sad and did not receive external funding. It was supported by the COST Action project on tick-borne disease prevention and the Balkan Association for Vector-Borne Diseases.