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Helminth infection is highly prevalent in indigenous chickens reared in semi-scavenging/ scavenging systems in Bangladesh. Here, we estimated the prevalence of gizzard worm infection in indigenous chickens, the detection of the worm-induced pathologies, the development of ex vivo cultural protocol, and anthelmintic efficacy. We randomly collected and examined 390 chickens and isolated worms from the gizzard and proventriculus. The isolated worms were identified as Cheilospirura hamulosa Diesing, 1861. The overall prevalence of C. hamulosa was 33.1% (129 out of 390). Prevalence of the worm was almost similar in both sexes but significantly (p <0.05) higher in adult chickens (44.3%) and in the summer season (47.1%). In heavy infections, C. hamulosa destroyed the muscular layer of the gizzard. The presence of brown necrotic tissues and curd-like caseous materials was detected in the affected gizzards. In severe cases, the horny lining of the gizzard was inflamed, necrotized and marked by multiple holes and brick-red colored spots. Liquefied, fetid materials oozed out from the muscular layer in extensive cases. Histopathological examination showed marked infiltrations of eosinophils. In serum-supplemented M199 and DMEM, adult C. hamulosa survived well and reproduced. Levamisole (LEV) and ivermectin (IVM) efficiently killed the worm. However, albendazole (ABZ), mebendazole (MBZ) and piperazine (PPZ) did not kill the worms. Our results suggest that C. hamulosa is highly prevalent in semi-scavenging chickens in Bangladesh. LEV and IVM can be used to treat and control the infection in chickens.

Stegophorus macronectes (Johnston & Mawson, 1942) is a gastrointestinal parasite found in Antarctic seabirds. The original description of the species, which was based only on females, is poor and fragmented with some unclear diagnostic characters. This study provides new morphometric and molecular data on this previously poorly described parasite. Nuclear rDNA sequences (18S, 5.8S, 28S and internal transcribed spacer (ITS) regions) were isolated from S. macronectes specimens collected from the chinstrap penguin Pygoscelis antarctica Forster on Deception Island, Antarctica. Using 18S rDNA sequences, phylogenetic analyses (maximum likelihood, maximum parsimony and Bayesian inference) of the order Spirurida were performed to determine the phylogenetic location of this species. Primer pairs of the ITS regions were designed for genus-level identification of specimens, regardless of their cycle, as an alternative to coprological methods. The utility of this molecular method for identification of morphologically altered specimens is also discussed.

We describe Hedruris dratini n. sp. (Nematoda, Hedruridae) from Hydromedusa tectifera and Phrynops hilarii in Argentina based on morphological and molecular characters. Also, we provide information about its life cycle. The new species differs from other species of the genus by possessing the excretory pore, nerve ring and deirids at equal distance from the anterior end. Additionally, H. dratini n. sp. has mammilated eggs and males possess nine pairs of caudal papillae. The subadults and adults of H. dratini n. sp and H. orestiae were characterized by sequencing the small subunit ribosomal DNA (18S). We present for the first time a life cycle of a species of Hedruris that includes an amphipod as intermediate host and a reptile as definitive host. Furthermore, we analysed the host and geographic distribution of all Hedruris species. Although the genus has a cosmopolitan distribution and parasitizes a great host diversity, the majority of species have a Gondwanian distribution, with amphibians being the preferred hosts.

Thelazia callipaeda is a zoonotic vector-borne nematode that infects and causes eye disease among a wide range of domestic and wild mammals, including humans. We describe an unusual case of reinfection by this nematode in Serbia and call for a focus on preventive measures in endemic areas.

Background Spirocerca lupi is a nematode that infects domestic dogs and wild carnivores. Methods This study retrospectively analyzed postmortem records between 1989 and 2024 to assess S. lupi -associated lesions in coyote necropsies. In addition, it conducted molecular characterization of 18S rRNA and cytochrome oxidase subunit 1 ( cox1 ) gene fragments of larvae found at necropsies. Fecal samples from free-ranging coyotes were molecularly examined for S. lupi 18S DNA. Results Of the 39 coyote cases, 33 (84. 6%) presented S. lupi -associated lesions. A significant association was observed between the presence of Spirocerca nematodes and the development of esophageal granulomas and aortic aneurysms. In addition, an atypical case of spinal cord invasion was documented, representing the first reported occurrence of this condition in coyotes. Out of all fecal samples tested, 4.6% were positive for S. lupi infection. Conclusions The obtained cox1 sequence revealed a complete similarity to S. lupi isolated from the Andean fox Lycalopex culpaeus from Peru, suggesting its transmission between wild canid populations. These findings indicate that coyotes play a significant role in S. lupi transmission dynamics and highlight the need for further research on the ecological interactions between domestic and wild canids in Costa Rica. Graphical abstract

Recent examinations of spirurid nematodes (Spirurida) from deep-sea or coral reef marine fishes off New Caledonia, collected in the years 2006–2009, revealed the presence of the following five species: Ichthyofilaroides novaecaledoniensis (Moravec et Justine, 2009) n. gen., n. comb. (transferred from Ichthyofilaria Yamaguti, 1935) (females) (Guyanemidae) from the deep-sea fish Hoplichthys citrinus (Hoplichthyidae, Scorpaeniformes), Philometra sp. (male fourth-stage larva and mature female) (Philometridae) from Epinephelus maculatus (Serranidae, Perciformes), Ascarophis ( Dentiascarophis ) adioryx Machida, 1981 (female) (Cystidicolidae) from Sargocentron spiniferum (Holocentridae, Beryciformes), Ascarophis ( Ascarophis ) nasonis Machida, 1981 (males and females) from Naso lituratus and N . unicornis (Acanthuridae, Perciformes), and Ascarophisnema tridentatum Moravec et Justine, 2010 (female) from Gymnocranius grandoculis (Lethrinidae, Perciformes). Two species, I . novaecaledoniensis and A . nasonis , are redescribed based on light microscopical (LM) and scanning electron microscopical (SEM) examinations, the latter used in these species for the first time. Morphological data on the specimen of A . tridentatum from the new host species are provided. Philometra sp. (from E . maculatus ) most probably represents a new gonad-infecting species of this genus. The newly established genus Ichthyofilaroides n. gen. is characterized mainly by the presence of a small buccal capsule and by the number and distribution of cephalic papillae in the female; it is the sixth genus in the Guyanemidae. L’étude récente de nématodes Spirurida de poissons marins de mer profonde ou des récifs coralliens au large de la Nouvelle-Calédonie, collectés dans les années 2006-2009, a révélé la présence des cinq espèces suivantes : Ichthyofilaroides novaecaledoniensis (Moravec et Justine, 2009) n. gen., n. comb. (transféré depuis Ichthyofilaria Yamaguti, 1935) (femelles) (Guyanemidae) du poisson de profondeur Hoplichthys citrinus (Hoplichthyidae, Scorpaeniformes), Philometra sp. (larve mâle de quatrième stade et femelle mûre) (Philometridae) d’ Epinephelus maculatus (Serranidae, Perciformes), Ascarophis (Dentiascarophis) adioryx Machida, 1981 (femelle) (Cystidicolidae) de Sargocentron spiniferum (Holocentridae, Beryciformes), Ascarophis (Ascarophis) nasonis Machida, 1981 (mâles et femelles) de Naso lituratus et N. unicornis (Acanthuridae, Perciformes), et Ascarophisnema tridentatum Moravec et Justine, 2010 (femelle) de Gymnocranius grandoculis (Lethrinidae, Perciformes). Deux espèces, I. novaecaledoniensis et A. nasonis , sont redécrites sur la base de la microscopie optique et de la microscopie électronique à balayage, cette dernière étant utilisée pour la première fois chez ces espèces. Des données morphologiques sur le spécimen d’ A. tridentatum de la nouvelle espèce hôte sont fournies. Philometra sp. (d’ E. maculatus ) représente très probablement une nouvelle espèce infectant les gonades de ce genre. Le genre nouvellement établi Ichthyofilaroides n. gen. se caractérise principalement par la présence d’une petite capsule buccale et par le nombre et la répartition des papilles céphaliques chez la femelle. C’est le sixième genre des Guyanemidae.

Background Infectious keratoconjunctivitis (IKC) is a common ocular disease of ruminants worldwide. Recently, an outbreak of infectious keratoconjunctivitis was observed in the European bison in Poland. Hundreds of animals show conjunctival congestion, corneal opacity, and ulceration, leading to total blindness. The present study aimed to examine the ocular changes of European bison and patterns of the disease occurrence with special emphasis on the role of Thelazia nematodes in the development of IKC. Results The eyes of 131 European bison, showing ocular signs and clinically healthy, were collected in Poland in 2021 – 2022 and subjected to parasitological and histopathological examination. Histopathology showed varying lesions, including corneal erosions or ulcers, diffuse purulent infiltrates to lymphocytic infiltration in the cornea, and lymphocytic or mixed conjunctivitis with CALT stimulation. The severity of ocular changes was higher in European bison from mountain areas and during the winter season. Two species of Thelazia nematodes – T. skrjabini and T. gulosa have been isolated from eyes. Prevalence of infection reached over 66.4%, and the infection intensity ranged from 1 to 16 nematodes per individual. Although nematodes of the genus Thelazia were prevalent in European bison, their occurrence did not correspond with the severity of ocular changes. Conclusions The results of our studies allowed to identify patterns related to the first outbreak of infectious keratoconjunctivitis in European bison. Living in mountain areas and winter season were the most predisposing factors for the development of ocular changes. Despite the high prevalence of Thelazia nematodes in the present study, their role in forming ocular lesions was not confirmed.

Nematodes of the genus Thelazia (also referred to as eyeworms) pose a growing concern for wild and domestic ruminants. This study aimed to investigate the prevalence, species composition, and associated ocular pathology of Thelazia infection in several European bison populations in Poland. The eyes of 223 European bison were examined over five years (2020–2024). Nematodes of the genus Thelazia were identified based on morphometrical and molecular analysis of the cox 1 sequences. Epidemiological analysis of Thelazia infection in relation to age, sex, genetic line of European bison, as well as severity of ocular changes, habitat, and season, was performed. Morphometrical and molecular analysis revealed the presence of two species – Thelazia gulosa and T. skrjabini . Nematodes were detected in 61.9% of examined animals, with T. skrjabini being significantly more prevalent than T. gulosa ( p  < 0.001). Infection with T. skrjabini was significantly associated with the severity of ocular lesions, which might suggest higher vulnerability of European bison to this eyeworm species. In the study period, prevalence of Thelazia infection significantly decreased in the Lowland line of European bison ( p  = 0.022) while it remained unchanged in the Lowland-Caucasian bison ( p  = 0.328). The study shows that Thelazia spp. is a common parasite of the European bison, equally spread across different studied populations, irrespective of habitat, geographical region, season or individual factors. It may indicate that thelaziosis occurs endemically in the Polish population of the European bison.

The genus Spirocerca includes nematodes that parasitize the stomach and the oesophagus of carnivores, chiefly canids. Herein, we provide new data about the morphological, histopathological, and molecular characterization of Spirocerca sp. in Andean foxes ( Lycalopex culpaeus ) in Chile. Intact immature worms, identified as Spirocerca sp., were recovered in the lumen of the stomach from two foxes. Histologically, worms morphologically consistent with spirurid nematodes were present within the wall of the stomach and surrounded by nodular areas of inflammation with central necrotic debris. Molecular analysis of the cox 1 gene yielded 19 sequences and 5 nucleotide sequence types with 99.95 to 99.98% similarity, being shared between both foxes. Nucleotide similarity ranged from 93.1 (with genotype 2 of S. lupi and S. vulpis ) to 95.8% (with genotype 1 of S. lupi ), a higher similarity than noted from sequences of S. lupi from an Andean fox from Peru (91.0 to 93.3%). However, the Poisson Tree Processes for species delineation did not support the existence of a new species Spirocerca . Phylogenetic and nucleotide analyses suggest that these specimens belong to a new variant or genotype of S. lupi or to a cryptic species. Whether the presence of the worms in the stomach has to do with genotypic differences in parasites or host or some combination is uncertain. Spirocerca lupi has never been found in Chilean dogs and must be investigated.

Cylicospirura Vevers, 1922 is a genus of gastrointestinal spirurid nematodes parasitizing mainly felid but also canid, hyaenid and dasyurid hosts. Presently, 11 species are recognized worldwide, of which 4, Cylicospirura subaequalis, Cylicospirura felinea, Cylicospirura crocutae and Cylicospirura pardalis, have been recorded from African carnivores. In the present study, we describe Cylicospirura phiri n. sp. from hyaenas, namely Crocuta crocuta (type host) in Zimbabwe and Hyaena hyaena in Cameroon. The new species is the second species in the genus with bicuspid teeth. Furthermore, it can be distinguished from its congeners by a combination of characters, such as the absence of accessory teeth, the length and shape of the muscular oesophagus, position of the nerve ring, deirids and excretory pore in relation to the muscular oesophagus, the position of the vulva, spicule length and the shape of the female tail. Additionally, based on new material, detailed morphological descriptions are provided for C. crocutae and C. pardalis whose original descriptions were based on fragmented material. The material from Felis lybica, currently deposited as C. subaequalis, is described as C. felinea. First-time scanning electron micrographs are presented for the 4 species confirmed in African carnivores.