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Human larva migrans is a zoonotic disease caused by larvae of various nematode species, with all previously confirmed pathogens originating from mammalian reservoirs. In 2020, a case series in Vietnam reported instances of cutaneous larva migrans caused by avian eyeworm larvae of the Oxyspirura genus. This nematode genus, belonging to the Thelaziidae family, includes 84 species that mainly parasitize the eyes of various bird species. They utilize different arthropod intermediate hosts, such as cockroaches, grasshoppers, and crickets, in their life cycle. Although the 18S sequences of the larvae were analyzed, the precise identification of the pathogen at the species level remains inconclusive. This study aims to identify the exact causative agent at the species level by analyzing larvae from a patient and adult eyeworms collected from chickens raised in his family using morphological and molecular methods. Molecular analysis of 18S rDNA, ITS2, and cox 1 sequences revealed genetic identity between the larva from the patient and adult eyeworms from chickens, as well as with Oxyspirura mansoni from Thailand and Bangladesh. Additionally, morphological examinations further confirmed the adult chicken eyeworms as Oxyspirura mansoni . These findings confirm that O. mansoni larvae are responsible for human larva migrans, marking the first confirmation of nematode larvae from birds (chickens) as a pathogen causing an emerging neglected tropical disease in humans. Given the widespread distribution of this nematode, further research is crucial to investigate this neglected disease, not only in Vietnam but also in other regions. Understanding appropriate treatments and transmission routes is essential to prevent infections in both chickens and humans.

Background In Europe, the first Thelazia callipaeda infections were found in the eyes of some dogs in Italy three decades ago. Since that time, this vector-borne nematode species has been diagnosed in domestic and wild carnivores and humans in some western European countries. During the last few years, autochthonous thelaziosis of dogs, red foxes, cats and humans has also been reported from eastern Europe. The first cases of ocular infections caused by T. callipaeda have been described in dogs living in the eastern and southern part of Slovakia and Hungary. Methods Whitish parasites found in the conjuctival sac and/or under the third eyelid of one or both eyes of animals were removed and morphologically identified according to species and sex. To confirm the morphological identification with molecular analysis a single step conventional PCR was carried out. Results A total of 116 adult worms (1–37 per dog, median: 7, IQR: 14.5 and 7 from a cat) were collected from the eyes of 11 animals. Nematodes were identified as T. callipaeda according to the morphological keys and molecular analysis. The sequences of a portion of the mitochondrial cytochrome c oxidase subunit 1 ( cox 1) gene were identical to those representing T. callipaeda haplotype 1, previously reported in neighbouring and other European countries. Since the infected cat and dogs had never travelled abroad, all of the cases were autochthonous thelaziosis. Conclusions The present study reports the first case of thelaziosis in a cat and new cases in 10 dogs found in the southern and northern region of Hungary, respectively. Further studies are needed to clarify whether wild carnivores (e.g. red foxes, golden jackals) may act as reservoirs of this eyeworm species in the country.

A 12-year old Elo dog was presented with recurring symptoms of conjunctivitis in November 2019. A single whitish nematode was found upon inspection of the eye and identified as a Thelazia callipaeda male. The morphological identification of the eye worm was supported by analysis of a partial cytochrome c oxidase I (cox1) gene sequence. The dog lived in Lower Saxony, northwestern Germany, and had not visited regions known to be endemic for T. callipaeda. This suggests that a local transmission cycle of this zoonotic nematode may exist in Germany.

Background Five species of the Phortica genus (Diptera: Drosophilidae) are known in Europe and the Middle East. Among these, Phortica variegata and Phortica okadai are better known for their role as vectors of the zoonotic eyeworm Thelazia callipaeda . Other species, such as Phortica semivirgo and Phortica oldenbergi , have been studied less. Given the paucity of data about these Phortica spp. vectors, we explored the population dynamics and ecology of Phortica spp. in an area highly endemic for T . callipeada (Manziana, Rome, Central Italy). Methods Phortica spp. flies were collected over a 3-year period (2018–2020) during their active season (April–October) with a sweep net while hovering around fermenting fruits or a human operator acting as baits. Collected flies were morphologically identified and tested for a T . callipeada infection and for the presence of Wolbachia , by polymerase chain reaction (PCR). Population dynamics of species collected was associated to environmental drivers through generalized additive models. Results Of the 5564 flies collected, 90.8% were P . variegata , 9.1% were P . oldenbergi , 0.05% were P . semivirgo , and one specimen was P . okadai . Only P . variegata scored molecularly infected with T . callipeada throughout the 3-year sampling period (1.8%). Phortica oldenbergi , observed consistently during the entire sampling period, exhibited a marked preference for fruit traps, contrasting with the lachryphagous activity of P . variegata . Analysis of environmental drivers of P . oldenbergi and P . variegata population dynamics indicated temperature, wind speed, and pressure as significant factors. In addition, Wolbachia pipientis endosymbiont was detected in P . oldenbergi and P . okadai . Conclusions For the first time, this study analysed several ecological aspects of Phortica species coexisting in a T . callipeada endemic area, highlighting different behaviors in the same environment and their vectorial role. Notably, this is also the first report of the presence of P . oldenbergi in Italy and P . okadai in Europe, underscoring the importance of extensive sampling for detecting potential vectors and alien species with direct implications for vector-borne disease epidemiology. Graphical Abstract

Background In camels, thelaziosis is mainly caused by Thelazia leesei Railliet & Henry, 1910, a little-known eyeworm species. Given the paucity of scientific data, this study aimed to provide new insights into the morphology, molecular characterization, and phylogenetic relationship of T. leesei and its occurrence in camels from Iran, where animals suffer from the high burden of eyeworms. Methods From December 2020 to November 2022, slaughtered camels ( n  = 400) of different sex and age groups were examined in Sistan-va-Baluchestan province in Southeast Iran’s local abattoirs. Adult eyeworms were fixed and stored for morphological identification by light and scanning electron microscopy (SEM). Polymerase chain reaction (PCR) products corresponding to the partial sequences of the mitochondrial cytochrome c oxidase subunit I ( cox 1) of eyeworms were Sanger sequenced and analyzed phylogenetically. Results A total of 118 (29.5%) camels from all five counties examined were infected with eyeworms, with an abundance of 0.9 and a mean intensity of 3.2 (i.e., up to 18 worms from a single animal). The infection rate was higher in camels older than 4 years of age ( P  = 0.01901). Lachrymation was associated with infection in animals ( P  < 0.00001). The morphology of our specimens resembled that of T .  leesei , with the exception of the position of the nerve ring and esophagus length. Genetic analysis showed that the cox 1 partial sequences of our T. leesei specimens had genetic distances of 8.8% to 13.5% compared with other Thelazia species. Conclusions On the basis of the morphometrics and morphological characteristics, we identified our specimens as T .  leesei . In the phylogenetic tree, T. leesei herein isolated formed a monophyletic group together with its congeners, and T .  leesei formed a sister clade to T. lacrymalis . In addition, we demonstrated the epidemiology of the infestation of T .  leesei in camels in the endemic areas of southeastern Iran. The data presented are crucial for better understanding the pathogenic role of T. leesei and developing effective treatment strategies. In particular, studies on the intermediate host(s) of T. leesei in these regions will support effective control strategies for this parasitosis. Graphical Abstract

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

Background Thelazia callipaeda is an emerging zoonotic nematode that infects the eyes of domestic and wild mammals across Europe and is transmitted by drosophilid flies of the genus Phortica . Despite increasing reports across the continent, its distribution in wildlife in southeastern Europe remains poorly understood. To our knowledge, this study represents the first comprehensive parasitological and molecular investigation of T. callipaeda in wild carnivores in Croatia. Methods Between 2020 and 2023, a total of 2632 animals, either legally hunted or found dead, were examined. These included 1794 red foxes ( Vulpes vulpes ), 443 golden jackals ( Canis aureus ), 180 European badgers ( Meles meles ), and 215 stone martens ( Martes foina ). Ocular examination and nematode collection were conducted, followed by morphological identification and COI gene sequencing for species confirmation. Results The overall prevalence of T. callipaeda infection was 3.9% in red foxes and 4.3% in golden jackals. No infections were detected in badgers or martens. The infections were geographically restricted to continental regions, with the highest prevalence recorded in eastern counties. Seasonal patterns were evident in red foxes, where infection rates and reproductive activity peaked in autumn and winter. In contrast, golden jackals showed more stable infection rates throughout the year. A significant proportion of infections involved gravid females, particularly in jackals (73.7%), suggesting their critical role in sustaining transmission cycles. Molecular analysis confirmed that all isolates belonged to T. callipaeda haplotype 1. Conclusions These findings highlight the established presence of T. callipaeda in Croatian wildlife and reveal distinct host-specific patterns in prevalence, seasonality, and reproductive dynamics. Red foxes may act as seasonal reservoirs of infection, while golden jackals could serve as year-round reservoirs. Considering the zoonotic potential of this parasite, further surveillance and integrated monitoring of vectors and vertebrate hosts are essential for evaluating future risks to public and veterinary health in the region. Graphical abstract

We identified a Thelazia callipaeda eyeworm in an American black bear in Pennsylvania, USA, on the basis of its morphological features and molecular analysis. Our finding highlights emergence of a T. callipaeda worm sylvatic transmission cycle in the United States.

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.

Background The spirurid nematode Thelazia callipaeda , also called the “Oriental eyeworm”, is the causative agent of canine and human ocular thelaziosis. In the past few years it has started to spread across central Europe and new endemic areas have been established. The present study reports on the first four autochthonous cases of canine ocular thelaziosis in the territory of Slovakia, Central Europe. Results All cases were recorded in dogs living in eastern Slovakia, near the border with the Ukraine. All worms collected were investigated morphologically and their identification further confirmed at the molecular level by PCR amplification and direct sequencing. Nucleotide sequences of partial T. callipaeda cox 1 and 28S rDNA gene fragments isolated from Slovak dogs were submitted to the GenBank database under accession numbers KY476400 and KY476401, respectively. Conclusions Considering that all four cases were diagnosed in animals that had never travelled abroad, there is clear evidence of an autochthonous occurrence and thereby the further spread of T. callipaeda across Europe. Moreover, at latitude of 48°N, these cases might be considered as the northernmost recorded cases of autochthonous in western and Central Europe.