This opinion piece highlights the role of migratory birds in the spread of ticks and their role in the circulation and dissemination of pathogens in Europe. Birds with different lifestyles, i.e., non-migrants residing in a specific area, or short-, medium-, and long-distance migrants, migrating within one or several distant geographical regions are carriers of a number of ticks and tick-borne pathogens. During seasonal migrations, birds that cover long distances over a short time and stay temporarily in different habitats can introduce tick and pathogen species in areas where they have never occurred. An increase in the geographical range of ticks as well as the global climate changes affecting the pathogens, vectors, and their hosts increase the incidence and the spread of emerging tick-borne diseases worldwide. Tick infestations of birds varied between regions depends on the rhythms of tick seasonal activity and the bird migration rhythms determined by for example, climatic and environmental factors. In areas north of latitude ca. 58°N, immature Ixodes ricinus ticks are collected from birds most frequently, whereas ticks from the Hyalomma marginatum group dominate in areas below 42°N. We concluded that the prognosis of hazards posed by tick-borne pathogens should take into account changes in the migration of birds, hosts of many epidemiologically important tick species.

Tick-borne encephalitis (TBE) is the most common viral neurological disease in Eurasia. It is usually transmitted via tick bites but can also occur through ingestion of TBEV-infected milk and dairy products. The present paper summarises the knowledge of the food-borne TBEV transmission and presents methods for the prevention of its spread. The incidence of milk-borne TBE outbreaks is recorded in central, eastern, and north-eastern Europe, where Ixodes ricinus, Ixodes persulcatus, and/or Dermacentor reticulatus ticks, i.e., the main vectors of TBEV, occur abundantly. The growing occurrence range and population size of these ticks increases the risk of infection of dairy animals, i.e., goats, sheep, and cows, with viruses transmitted by these ticks. Consumers of unpasteurised milk and dairy products purchased from local farms located in TBE endemic areas are the most vulnerable to alimentary TBEV infections. Familial infections with these viruses are frequently recorded, mainly in children. Food-transmitted TBE can be monophasic or biphasic, and some of its neurological and psychiatric symptoms may persist in patients for a long time. Alimentary TBEV infections can be effectively prevented by consumption of pasteurised milk and the use of TBEV vaccines. It is recommended that milk and dairy products should be checked for the presence of TBE viruses prior to distribution. Protection of dairy animals against tick attacks and education of humans regarding the epidemiology and prophylaxis of TBE are equally important.

Due to their mass occurrence in some environments and high aggressiveness, blackflies (Simulium spp.) represent the most bothersome arthropods attacking humans. In this study, we describe the medical effects of blackfly infestations in humans in southeastern Poland. Local and systemic reactions to blackfly bites were monitored in 418 patients (61.24% of females and 38.76% of males) of medical centers. Only skin lesions at the site of the bites were found in 88.52% of the patients, whereas accompanying systemic reactions were diagnosed in 11.48%. The most common signs observed in the area of the bites were pruritus (94.74%), burning (55.02%), edema (44.02%), and erythema (40.91%). The skin lesions, which were most often grouped small papules and papular and purpuric lesions with a varied range, typically persisted for several days, or for several weeks in some patients. Statistical analyses confirmed that the persistence of the skin lesions did not depend on the sex of the patients and the number of blackfly infestations. The systemic reactions to the components of the blackfly saliva were manifested by headache, increased body temperature, arthralgia, lymphadenopathy, and menstrual disorders in the females. The patients were most often attacked simultaneously by many blackflies on exposed parts of the body, mainly the upper limb, lower limb, head, and neck areas. The investigations indicate that blackflies are an important etiological factor of dermatitis and other symptoms in humans; hence, they should be considered in clinical diagnosis.

Background: The territorial expansion and increased population size of haematophagous arthropods (i.e., the castor bean tick Ixodes ricinus (Ixodida: Ixodidae) and the deer ked Lipoptena cervi (Diptera: Hippoboscidae)) has enhanced the risk of human infestations in Europe. The aim of our study was to present skin lesions induced by tick and deer ked bites in patients from recreational forest regions in southeastern Poland and pay attention to features of skin changes that may be useful in differential diagnosis. Methods: We compare the skin lesions after I. ricinus and L. cervi bite and draw attention to the biological and ecological traits of both ectoparasites, which may be diagnostically relevant for determination of the cause of skin symptoms reported by patients. Results: I. ricinus bites lead to development of erythematous-infiltrative poorly demarcated lesions with a centrally located bite mark, which usually disappears within one to several days. In turn, L. cervi bites leave irregularly shaped scattered erythematous papules. The papules may persist for up to one year and are accompanied by itching. Conclusions: Correct assessment of the clinical picture and its association with an arthropod bite (e.g., tick or deer ked) is highly important for further diagnostic procedures (i.e., differentiation of skin lesions developing in tick-borne diseases and, consequently, correct choice of pharmacological therapy). I. ricinus and L. cervi differ in their developmental cycles and rhythms of activity, which indicates that both species should be considered potential causative agents in the differential diagnosis of skin lesions when the patient has been bitten by an arthropod in autumn and winter months.

Rickettsiae from the spotted fever group, i.e. the etiological agents of tick-borne lymphadenopathy/Dermacentor-borne necrotic erythema and lymphadenopathy (TIBOLA /DEBONEL) syndrome, are associated with ticks, including Dermacentor marginatus and Dermacentor reticulatus. The expansion of these ticks into new areas increases the risk of infection of their hosts with tick-borne pathogens. The study summarises the importance of 2 species from the genus Dermacentor, i.e. D. marginatus and D. reticulatus, in the spread of spotted fever group rickettsiae in various regions of Europe. The study also focuses on the determinants of the presence of vectors and transmission of rickettsiae, as well as the effects of human infections with these pathogens. The climate changes observed nowadays affect vectors and increase the incidence and spread of tick-borne diseases worldwide. Due to the existing risk of exposure to an increasing number of people, knowledge about the course of these serious diseases and their etiological factors should be disseminated among healthcare professionals as well as in society. There is a great challenge for epidemiological services to provide access to medical and veterinary facilities in order to diagnose and treat rickettsioses. Therefore, the development of a strategy for tick control and the popularisation of knowledge concerning prophylaxis of tick-borne diseases is indispensable.

Increased human mobility elevates the risk of exposure of companion animals travelling with their owners or imported from other regions to tick attacks. In this study, we highlight the potential role of dogs and cats taken for tourist trips or imported animals in the spread of ticks and tick-borne pathogens. The Rhipicephalus sanguineus tick, which is a vector of numerous pathogens causing diseases in animals and humans, is imported most frequently from endemic areas to many European countries. Additionally, alien tick species with high epizootic and epidemiological importance can be imported on dogs from other continents. Companion animals play an even greater role in the spread of autochthonous tick species and transmission of tick pathogens to other animals and humans. Although the veterinary and medical effects of the parasitism of ticks carried by companion animals travelling with owners or imported animals are poorly assessed, these animals seem to play a role in the rapid spread of tick-borne diseases. Development of strategies for protection of the health of companion animals in different geographic regions should take into account the potential emergence of unknown animal tick-borne diseases that can be transmitted by imported ticks.

Objective. This study presents for the first time a case of Hyalomma excavatum hyperparasitism and an analysis of this phenomenon in terms of its potential role in the biology of ticks and epidemiology of tick-borne diseases. Materials and method. Two partially engorged H. excavatum females, one fully engorged female, and 5 males were collected from a naïve rabbit and placed together in a rearing chamber at a temperature of 25 °C and 75% humidity. Results. 3-4 days after tick detachment from the host's skin, one partially engorged H. excavatum female was observed attached to the idiosoma of the fully engorged conspecific female. Conclusions. This study and observations of other authors confirm that partially engorged ixodid ticks can re-infest the host, and even co-feeding fully engorged ticks in order to collect the blood meal that is indispensable for important physiological processes. However, inefficient feeding of a partially engorged female on another conspecific female may reduce its reproductive performance and disturb the development of eggs and larvae. It seems that parasitism of a tick on another conspecific specimen, when at least one of them is infected by a microorganism, may be a yet poorly explored route of transmission of pathogens or symbionts between the ticks. Initiation of feeding by a hungry or partially engorged tick on a fully engorged specimen is an attempt to obtain food in the drastic conditions of the absence of a target host. Tick hyperparasitism with concurrent pathogen transmission can contribute to the genospecific diversity of pathogens in vectors and hosts.

Ixodiphagus endoparasitoid wasps are natural tick enemies that can reduce their abundance. In this study, we investigated the presence of Ixodiphagus hookeri in Haemaphysalis concinna and Ixodes ricinus ticks in the Slovak Karst (southern Slovakia) and analysed the ecological and physiological relationships in the parasitoid-host system. Unfed H. concinna and I. ricinus nymphs harvested from vegetation were fed on rabbits. The engorged specimens were kept at 25 °C and 75% RH until the emergence of the adult wasps. For the first time in Europe, we found the presence of I. hookeri in two species of ticks collected in the same locality and compared their development in these tick species. The prevalence of wasps in H. concinna and I. ricinus during their spring activity was estimated at 10.64% and 27.78%, respectively. The presence of the wasps did not affect the duration of nymph feeding. Engorged wasp-infected ticks achieved higher body mass than non-infected specimens. In both tick species, there were no differences in the length of the development period and the number and sex ratio of adult I. hookeri. The analysed indicators and characteristics of the I. hookeri wasp-tick system can be used in research on tick control.