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Vector-Borne Pathogen DNA Detected in 10 of 23 Finnish Moose Calves

Wild moose calf in Denali National Park
Research · Disease, parasites & microbiology

PCR screening detected DNA from at least one of three vector-borne pathogen groups in 10 of 23 moose (Alces alces) calves examined in Finland. The study shows that these microorganisms can circulate in calves during their first season of life, but the small, geographically concentrated sample cannot be used to estimate prevalence in Finland’s moose population.

Twenty-two calves were about six months old and were shot by hunters around Parainen in southwestern Finland in October 2022. One additional sample came from an emaciated calf found dead in eastern Finland.

Trypanosoma DNA was the most frequent finding

Trypanosoma DNA was detected in eight calves. All sequences belonged to the TthII lineage of the Trypanosoma theileri complex, and three 18S rRNA haplotypes had not previously been recorded.

The tick-borne bacterium Anaplasma phagocytophilum was detected in four calves, while Bartonella DNA was found in two. Four calves carried DNA from two pathogen groups. Phylogenetic comparisons placed the detected lineages within broadly distributed pathogen populations rather than variants known only from southwestern Finland.

DNA detection is not the same as clinical disease

PCR shows that pathogen DNA was present in the blood sample at the time of collection. It does not by itself demonstrate clinical illness, quantify how severe an infection was or show that the detected organisms caused other health findings in the calves.

The study found no clear evidence that the molecular detections explained calf weight or other recorded health variables. The authors also note that effects can differ among pathogen lineages and with the age and condition of the host.

The percentages describe this sample, not all Finnish calves

Most animals came from one region and one short seasonal window, and almost all were obtained through hunting. The 10 positive calves therefore document early-life circulation of vector-borne microorganisms in the sampled animals rather than a national prevalence estimate.

The authors present the study as a baseline for broader wildlife-health surveillance. Future work combining moose, vector, host-condition and environmental data could clarify how these pathogens circulate as vector distributions and seasonal activity change in northern Europe. The study was not designed to quantify zoonotic risk.

Sources and image credit

  1. Filip-Hutsch, K., Oksanen, A., Heikkinen, P., Asman, M., Świsłocka-Cutter, M., Młocicki, D., Czopowicz, M., Anusz, K., Isomursu, M., & Werszko, J. (2026). Early-life exposure to vector-borne pathogens in moose calves from Finland: molecular and phylogenetic evidence. BMC Veterinary Research.Primary peer-reviewed open-access study of PCR detection and phylogenetic analysis in 23 Finnish moose calves.

Image: Mary Lewandowski/National Park Service — wild moose calf eating fireweed in Denali National Park and Preserve, Alaska, 12 July 2018; Wikimedia Commons / NPGallery. Public domain. Representative calf image, not an animal from the Finnish study. · Public domain — U.S. National Park Service · Source

About this content: This story was produced with AI assistance within an editorial workflow developed by Wildlife Vagabond. Editorial responsibility remains with Wildlife Vagabond.How AI is used

Disease, parasites & microbiology

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