Olga A. Loginova

Trichostrongylid nematodes are globally distributed gastrointestinal parasites of major veterinary and, in some cases, zoonotic importance. Accurate identification often requires an integrative approach because morphology alone may be compromised by specimen damage, cryptic diversity, and dimorphic species complexes. In the Philippines previous work has been largely limited to coproscopy, with no published DNA-based studies on adult trichostrongylids or scanning electron microscopy (SEM) documentation. Here, we provide an integrative characterization of Haemonchus contortus and Trichostrongylus axei recovered from a single goat in Mindanao, Philippines, in 2023. Identification was based on light microscopy, SEM, morphometry, and sequence data from the cox1 and ITS regions. Phylogenetic analyses and a haplotype network for H. contortus placed the Philippine material within a widely distributed lineage complex with weak geographic structuring. Because the study is based on parasites from a single host, the findings should be interpreted as a taxonomic and faunistic record rather than evidence for broader epidemiological or population-level patterns. This study provides the first molecular record of trichostrongylid nematodes from the Philippines and the first SEM-based documentation of H. contortus in the country. Broader sampling is needed to assess parasite diversity, distribution, genetic variation, and potential veterinary and public health relevance nationwide.

Trichostrongylid nematodes are globally distributed gastrointestinal parasites of major veterinary and, in some cases, medical importance. Among them, Haemonchus contortus is especially important as a highly pathogenic haematophagous species. Reliable diagnosis of trichostrongylids often requires an integrative approach because specimen damage, cryptic diversity, dimorphic species complexes, and possible hybridization may compromise identification based on morphology alone. In the Philippines, and particularly in Mindanao, previous work has been restricted largely to coproscopy, with no published studies on adult trichostrongylids using DNA-based methods or scanning electron microscopy (SEM). Here, we present an integrative characterization of H. contortus and Trichostrongylus axei recovered from a goat in Mindanao, Philippines, in 2023. Identification was based on light microscopy, SEM, morphometry with descriptive statistics, and sequence data from the CoxI and ITS regions. Phylogenetic analyses and a haplotype network for H. contortus indicated that the Philippine material belongs to a widely distributed lineage complex showing weak geographic structuring. In broadly distributed nematodes of small ruminants, the geographic origin of individual genotypes may therefore be difficult to infer from locality alone, as global host movements can facilitate admixture among parasite lineages. This study provides the first molecular record of trichostrongylid nematodes from the Philippines and the first SEM-based documentation of H. contortus in the country. These findings confirm the presence of economically important gastrointestinal nematodes in Philippine small ruminants and underscore the value of integrative diagnosis for accurate species delimitation. Broader sampling is needed to clarify parasite diversity, distribution, and genetic variation across the country.

Reindeer in the southern Palearctic remain poorly documented, especially regarding helminths. Limited data exist for their small, isolated, and conservation-important populations. Because helminths affect survival, reproduction, and population stability, and act as biogeographic indicators, knowledge of their diversity in these southern regions is considered essential for research and management purposes. A total of 242 fecal samples were obtained from 2012 to 2025 from reindeer inhabiting China, Kazakhstan, Mongolia, and Russia. These samples were examined by coproscopy. Morphological diagnoses were supplemented with DNA analyses. Trematodes of Paramphistomoidea, cestodes of Moniezia, and nematodes identified as E. rangiferi, O. macrotis, the dimorphic O. gruehneri/O. arctica, as well as Nematodirus, Capillaria, and unidentified small strongylids were revealed. All taxa detected in this study have been reported previously for R. tarandus and for the Palearctic, exception for Nematodirus sp. for the southern area. However, examinations of reindeer from selected regions in Russia, as well as Mongolia and Inner Mongolia (China) were carried out for the first time. Southern range limits were established for E. rangiferi in China and O. macrotis in Russia. Species O. macrotis has been proposed as a biogeographical marker for wild reindeer in the Eastern Siberia, while Capillaria may indicate domestic herds.

Rangifer tarandus in the southern Palaearctic remains poorly documented, particularly with respect to its helminth fauna. Existing data are scarce for these small, isolated, and conservation-significant populations. As helminths influence host survival, reproduction, and population stability, and may serve as biogeographical indicators, understanding their diversity in southern regions is of clear scientific and conservation importance. A total of 242 faecal samples were collected between 2012 and 2025 from populations of Rangifer tarandus in China, Kazakhstan, Mongolia, and Russia and analysed using coproscopic methods. Morphological identifications were complemented by molecular analyses where possible. Taxonomic identification of larvae of some nematodes was based on sequencing the internal transcribed spacer regions of ribosomal DNA; attempts to extract DNA from the eggs of helminths failed. The study revealed trematodes of the superfamily Paramphistomatoidea, cestodes of the genus Moniezia, and nematodes including Elaphostrongylus rangiferi, Orthostrongylus macrotis, the dimorphic Ostertagia gruehneri / Ostertagia arctica species, as well as Nematodirus, Capillaria, and unidentified small strongylids. All taxa identified have previously been reported in Rangifer tarandus within the Palaearctic, with the exception of Nematodirus sp. in the southern part of the range. This study also provides the first helminth records from faecal samples of wild Rangifer tarandus in several Protected Areas and regions, including the State Nature Reserve «Vasyugansky» (Novosibirsk Region, Russia), Altai State Nature Reserve (Republic of Altai, Russia), Baikal State Nature Reserve (Republic of Buryatia, Russia), Irkutsk Region (Russia), Olyokminsky State Nature Sanctuary and Tokinsko-Stanovoy National Park (both – Amur Region, Russia), as well as from semiwild Rangifer tarandus in Zabaykalsky Krai (Russia), Khövsgöl National Park (Mongolia), and Inner Mongolia (China). The southernmost known distribution limits were established for Elaphostrongylus rangiferi and Orthostrongylus macrotis.

Parasites of marine mammals are of significant interest in the fields of evolutionary biology, veterinary medicine, human health, conservation, and ecology. Therefore, every opportunity to study them should be seized. This study aimed to report on specimens of cestodes found in the small intestine of a gray whale (Eschrichtius robustus) in Chukotka, Russia, in 2024. The specimens were examined using light and scanning electron microscopy, histology, and molecular analysis. Based on their morphology and host specificity, the cestodes were identified as Priapocephalus eschrichtii. Analyses of the 18S and 28S ribosomal RNA genes confirmed a close relationship between P. eschrichtii and species of Tetrabothrius, which infect seabirds and whales. Sequences of the 18S, 28S, ITS2 rDNA, and gene CoxI mtDNA are reported here for the first time. More than 50 specimens of P. eschrichtii were detected in 1 meter of intestine of the whale with a maximum length of 50 cm. Chronic lymphoplasmacytic inflammation of the intestinal mucosa was observed in the infected whale. The eggs of the cestodes were clustered within an irregular membrane, which may contribute to multiple infestations of the host and lead to diseases that affect the whale’s health and survival. This study should be continued.

Zoo conditions are unique for reindeer, since domestic reindeer are not kept in captive facilities like cattle. In the zoo, reindeer are usually surrounded by many different animals that they would never encounter naturally. Thus, they might be infected with new helminths. Numerous petting zoos raise concerns about the safety of tactile interactions for human visitors. Our study is the first large-scale one. Qualitative and quantitative fecal analyses were carried out for 233 reindeer distributed over 50 Russian zoos according to the National Standard of the Russian Federation (GOST R 54627-2011) Ruminant animals—Methods of Laboratory Helminthological Diagnostics. Where possible, DNA analyses of helminths were performed targeting internal transcribed spacer region. As a result, F. hepatica, Paramphistomum sp., Moniezia sp. (including M. expansa), gastrointestinal strongylids (including Nematodirus spp.), Dictyocaulus sp., E. rangiferi, Trichuris sp., and Capillaria sp. were found in 106 (45%) zoo reindeer. All these helminths were previously reported in reindeer and pose no direct danger for humans. The intensity of invasions was mostly low. Fecal examination might be considered as an indirect method for mange diagnostics, as Chorioptes and Demodex mites were found in reindeer fecal samples. The latter may represent a novel species of mite specific for reindeer.

This work presents the results of studying the molecular characteristics of parasitic tapeworms Echinococcus canadensis. The helminths were discovered during the autopsy of a wolf (Canis lupus Linnaeus, 1758) killed by hunters in the Kirov oblast in 2021. A molecular phylogenetic study was performed by analyzing the sequence of a fragment of the first subunit of the mitochondrial cytochrome oxidase gene (CoxI). It was found that the detected echinococci belong to the G10 genotype of E. canadensis, which is common in wolves in the northern territories of the Holarctic. We discovered four positions at which the substitutions characteristic only of this genotype are revealed. A substitution at one of the positions that is characteristic exclusively for the representatives of the G10 genotype found in Russia and Finland was also discovered.

Zoo conditions are unique for reindeer, since even domestic reindeer are not kept in captive facilities like cattle. In the zoo, reindeer are usually surrounded by many different animals they would never encounter naturally. Thus they might pick up some new helminths. Numerous petting zoos raise an issue of safety of tactile communications for human visitors. Out study is the first large-scale one. Qualitative and quantitative fecal analysis was carried out for 233 reindeer distributed over 50 Russian zoos according to National Standard of the Russian Federation (GOST R 54627-2011) Ruminant animals—Methods of Laboratory Helminthological Diagnostics. Where possible, DNA analyses of helminths were performed targeting internal transcribed spacer region. In result, F. hepatica, Paramphistomum sp., Moniezia sp. (including M. expansa), gastrointestinal strongylids (including Nematodirus spp.), Dictyocaulus sp., E. rangiferi, Trichuris sp., and Capillaria sp. were found in 106 (45%) zoo reindeer. All these helminths were previously reported for reindeer and pose no direct danger for humans. Intensity of invasions was mostly low. Fecal examination might be considered as an indirect method for mange diagnostics, as Chorioptes and Demodex mites were found in reindeer fecal samples. The latter may represent a novel species of mite specific for reindeer.