Dermacentor reticulatus is the second most important tick species in Poland. Although the north-eastern region of Poland is considered typical for D. reticulatus and is treated as a contiguous area of Eastern populations of the meadow ticks, the occurrence of this tick species in this region to date has been recorded as separate foci. The present report supplements data on the geographical distribution of D. reticulatus in urban and natural biotopes of north-eastern Poland (Warmia and Mazury province). In 2015–2017 (during the springtime activity of ticks) adult questing D. reticulatus were found in 13 of 25 monitored localities. Six sites are located in urbanized areas, within the administrative borders of the city of Olsztyn and seven sites are in natural biotopes in the central part of Warmia and Mazury. A total of 398 adult D. reticulatus ticks, including 257 females and 141 males, were collected. A comparison of data grouped according to urban and natural type of area revealed no statistical differences between them. Taking into account the habitat type, the mean tick density was the highest in open landscapes. The identification of new foci D. reticulatus in the endemic areas of Lyme borreliosis, tick-borne encephalitis and canine babesiosis is crucial for determining the risk of diseases transmitted by ticks and taking proper preventive measures.

Proposed at the beginning of the twentieth century to explain the origin of eukaryotic organelles from prokaryotes, endosymbiosis is now medically defined by various interaction patterns between microorganisms and their residing hosts, best exemplified by the bacterial endosymbiont Wolbachia identified in arthropods and filarial nematodes, which can influence normal development, reproduction, survival and transmission of the hosts. Based on the transmission modes, vertical or horizontal, and the function of the endosymbionts, the host–symbiont dependence can be divided into primary or secondary. In dermatology, the role of endosymbionts in skin ectoparasitosis has aroused great interests in the past years. Riesia pediculicola is a primary bacterial endosymbiont in body lice Pediculus humanus, and supplement their hosts with vitamin B, especially pantothenic acid. In cimicosis, the Gram‐negative Wolbachia can synthesize biotin and riboflavin, which are crucial for the growth and reproduction of the bedbug Cimex lectularius. In human demodicosis and rosacea, further study is required to prove the pathogenic role of the Gram‐negative bacteria Bacillus oleronius or the Gram‐positive bacteria Bacillus cereus demonstrated in the Demodex mites. The high infection rate of adult female ticks Ixodes ricinus with the Gram‐negative bacteria Midichloria mitochondrii present in the mitochondria in diverse ovarian cells, with the high seroprevalence rate in tick‐exposed subjects, raises the possibility that this non‐pathogenic endosymbiont may play a role in immune response and successful transmission of the tick‐borne pathogen. The anaerobic protozoan Trichomonas vaginalis and bacteria Mycoplasma hominis are two obligate parasites in the urogenital epithelium, with partially overlapping symptoms. Intracellular localization of Mycoplasma hominis can avoid host immune response and penetration of antibiotics, while Trichomonas vaginalis infected with Mycoplasma hominis seems to have a higher cytopathic activity and amoeboid transformation rate. Further study on the biology and pathogenesis of different endosymbionts in dermatological parasitosis will help for the development of new treatment modalities.

The relationship between CRP gene (1271 G/A, 3’UTR) polymorphism and the serum levels of C-reactive protein (CRP), total cholesterol (Ch-T) and high density lipoprotein cholesterol (HDL-ch) was analysed in suckling crossbred [Polish Large White × Polish Landrace (♀) × × Duroc × Pietrain (♂)] piglets. CRP genotypes were identified by PCR-RFLP with Hinfi restriction enzyme. The levels of CRP, Ch-T, HDL-ch and white blood cell (WBC) counts were determined in blood samples collected from younger (21±3 days of age) and older piglets (35±3 days of age). There was a relationship between CRP gene (1271 G/A, 3’UTR) polymorphism and variations in the serum levels of CRP in piglets with normal WBC counts. The above relationship did not manifest itself in piglets with elevated WBC counts. The studied genotypes differed in their response to elevated WBC counts, and the noted differences were more pronounced in older piglets. The response of genotypes with weak CRP expression caused an increase in CRP levels and a decrease in the serum concentrations of Ch-T and HDL-ch. Such a response was not observed in the genotype with strong CRP expression.