Climate change is affecting human health worldwide. In particular, changes to local and global climate parameters influence vector and water-borne diseases like malaria, dengue fever, and tick-borne encephalitis. The Republic of Sakha in northern Russia is no exception. Long-term trends of increasing annual temperatures and thawing permafrost have corresponded with the northward range expansion of tick-species in the Republic. Indigenous communities living in these remote areas may be severely affected by human and livestock diseases introduced by disease vectors like ticks. To better understand the risk of vector-borne diseases in Sakha, we aimed to describe the increase and spatial spread of tick-bite cases in the Republic. Between 2000 and 2018, the frequency of tick bite cases increased 40-fold. At the start of the period, only isolated cases were reported in southern districts, but by 2018, tick bites had been reported in 21 districts in the Republic. This trend coincides with a noticeable increase in the average annual temperature in the region since the 2000s by an average of 1 °C. Maps illustrate the northward spread of tick-bite cases. A negative binomial regression model was used to correlate the increase in cases with a number of climate parameters. Tick bite case frequency per district was significantly explained by average annual temperature, average temperature in the coldest month of the year, the observation year, as well as Selyaninov’s hydrothermal coefficient. These findings contribute to the growing literature that describe the relationship between tick abundance and spread in Northern Latitudes and changes in temperatures and moisture. Future studies might use these and similar results to map and identify areas at risk of infestation by ticks, as climates continue to change in Sakha.

The subgenus Megatrypanum Hoare, 1964, with the type species Trypanosoma theileri Laveran, 1902, comprises stercorarian trypanosomes of mammals. A substantial portion of this subgenus consists of T. theileri-like trypanosomes parasitizing cervids and bovids worldwide. Similar to most other members of the genus Trypanosoma that lack obvious economic importance, the biology of T. theileri-like trypanosomes remains poorly understood. In particular, fundamental aspects such as their host specificity, host–parasite interactions, and the morphology of developmental stages have been studied only to a limited extent. In this work, we provide a detailed description of the development and cellular organization of T. theileri-like trypanosomes in the horsefly Hybomitra montana using transmission electron microscopy (TEM). We show for the first time that T. theileri-like trypanosomes possess a well-developed cytostome–cytopharyngeal complex, morphologically similar to those in other stercorarian trypanosomes. This complex is present in the studied trypanosomes at the epimastigote stage and degrades during metacyclogenesis. In the host ileum, epimastigotes and trypomastigotes at different stages of metacyclogenesis are embedded in a fibrillar matrix that isolates them from the gut lumen. This promotes their accumulation in the vector, thereby increasing the efficiency of future infection of the vertebrate host, which occurs via contamination of the oral mucosa.

Цель: изучение видового разнообразия эндобионтной фауны северного домашнего оленя эвенской и чукотской породы. Материалы и методы. Проведены исследования содержимого преджелудков 69 взрослых северных оленей двух пород: чукотской породы из Нижнеколымского района (40 голов) и эвенской породы из Оймяконского района (29 голов). Сбор содержимого преджелудков проводился во время массового забоя домашних северных оленей в ноябре 2022 г. Промежуток времени после забоя оленя до взятия проб составлял не более 20-25 минут. Пробы фиксировали 10% раствором формалина. Определение видов проведено по определителям Догеля В.А., 1929; Корниловой О.А., 2003, 2010. Сравнение видового состава эндобионтных инфузорий фауны животных исследованных пород проведена по коэффициенту сходства Жаккара-Малышева (Kj-m) и индексу общности фаун Чекановского-Сьеренсена (Ics). Результаты. В результате проведенных исследований установлено, что видовое разнообразие эндобионтной фауны домашних северных оленей чукотской и эвенской пород не значительно, но отличается. Определен видовой состав эндобионтных инфузорий на основании морфологических и морфометрических исследований. Всего идентифицировано 18 видов инфузорий, относящихся к 9 родам, в том числе у оленей эвенской породы - 18 видов по 9  родам и у оленей чукотской породы - 13 видов по 6 родам. Основу общих видов инфузорий для оленей чукотской и эвенской пород, разводимых в Якутии, составляют 3 вида Entodinium, 3 вида Epidinium, по 2 вида Diplodinium и Ostracodinium, по 1 виду Polyplastron, Enoploplastron и Dasytricha. Большее видовое разнообразие эндобионтов эвенской породы можно объяснить тем, что эвенская порода относится к таежному типу с более широким многообразием поедаемых кормовых растений, чем у тундровых оленей чукотской породы.