The study led by Prof. Sándor Hornok, Head of the HUN-REN–UVMB Climate Change: New Blood-sucking Parasites and Vector-borne Pathogens Research Group, jointly operated by HUN-REN and the University of Veterinary Medicine Budapest, has yielded findings of outstanding international significance. The Netherlands Food and Consumer Product Safety Authority (NVWA), as well as the veterinarian Dr. Orsolya Péteri, played a key role in the research. 

Over the course of one year, the researchers collected and analysed ticks in an outer district of Budapest. During the study, they discovered a series of mutations that can only be explained by mitochondrial genes integrated into the cell nucleus. Such genes had not previously been identified in ticks. In addition, they developed a new method for estimating the age of the affected ticks, which demonstrated that the mutant genes could, unusually, be detected more frequently in young ticks. Another major finding of the study was that a bacterial pathogen of Far Eastern origin was identified for the first time in an urban area of Central Europe, while a unicellular parasite hazardous to humans occurred in the samples at a prevalence that is outstanding even by global standards. The study reporting these findings was published in the prestigious Q1 journal Ticks and Tick-borne Diseases. 

In the temperate zone, ticks are regarded as the most important vectors of pathogens. In the European part of the Western Palaearctic, the two most widespread tick species are the common tick (Ixodes ricinus) and the ornate dog tick (Dermacentor reticulatus). One of the most important differences between them is that the former frequently feeds on birds and therefore has a fluctuating population, whereas this is not typical of the latter, whose resident populations are more exposed to local environmental effects. These two species also predominated at the Budapest habitat investigated in the study. 

Using a general PCR-based genetic testing method, the researchers identified a series of theoretically lethal mutations in the mitochondrial cox1 gene of local ornate dog ticks collected at the beginning of the season. Most of these ticks were young adults. However, when the complete mitochondrial gene set of the same ticks showing these alterations was examined using a more specific method, the lethal mutations were absent. This indicates that the mutations were present only in non-functional mitochondrial DNA integrated into the cell nucleus, known as NUMTs (nuclear mitochondrial DNA). Although the existence of NUMTs is known in humans and in many animal species, they had not previously been demonstrated in ticks. Their importance lies in the fact that their analysis can provide information on the origin, age and health status of a population, as well as on the effects of mutagenic substances present in the environment. 

The Budapest study also detected a zoonotic bacterium, Ehrlichia muris, which may have arrived with birds migrating from the Far East and, and according to the findings, has already become endemic, that is, permanently established, in the suburban habitat studied. In addition, whereas the zoonotic unicellular parasite Babesia microti is typically found in around 1–2% of common ticks in Hungary, it was detected in 36% of the specimens collected in Budapest in spring, which is considered a very high rate. Comparable prevalence has previously been reported only in ticks in North America, where, unlike in Europe, this species is responsible for most cases of human babesiosis, a parasitic infection that attacks red blood cells.