ИСТИНА

It is believed that when birds are infected with malaria parasites not found in their natural habitat, this can lead to serious negative consequences for the infected individuals. Given global warming and the potential expanding range of vectors, there is a growing threat of infection to bird species in northern latitudes that have never been exposed to tropical malaria parasites. In our study, we infected two groups of young siskins (Spinus spinus). One group was infected with a parasite species known to transmit in the North Palearctic, P. relictum (SGS1 lineage). The second group was infected with a parasite transmitted in Central and Southern Africa, P. ashfordi (GRW2 lineage). We compared the effects on the birds' physiological state using parameters like resting metabolic rate (RMR) and interleukin-6 (IL-6) levels. RMR gives insight into the energetic cost of the disease, and IL-6 is a pro-inflammatory cytokine indicative of the acute phase response within the innate immune system. Our results reveal that during the acute phase of SGS1 infection, a decrease in RMR and a reduction in IL-6 levels occur in siskins. For the GRW2 group, a similar trend in IL-6 was observed during the acute phase but not in the later stages of chronic infection. The RMR dynamics in the GRW2-infected siskins differed significantly from those in the SGS1 group. While our findings do not conclusively show that tropical malaria has more severe consequences for infected siskins, they do indicate distinct disease progressions between the two infected groups of birds.