Thelazia callipaeda ocular infection in two dogs in Belgium

Epidemiology of Ocular Thelaziosis in Domestic Dogs in Beijing

Thelazia callipaeda is a zoonotic parasitic nematode that lives in the ocular conjunctival sac of domestic and wild carnivores, lagomorphs, and humans, with Phortica spp. as its intermediate host. At present, the important role that domestic dogs play in thelaziosis has been studied in many countries. However, Beijing, which is the first city in China to experience human thelaziosis, has not yet conducted a comprehensive epidemiological analysis of the disease. In this study, we analyzed risk factors (region, season, age, sex, breed, size, living environment, diet, country park travel history, immunization history, anthelmintic treatment history, and ocular clinical symptoms) associated with the prevalence of thelaziosis in domestic dogs in Beijing. The overall prevalence of T. callipaeda in the study area was 3.17% (102/3215 domestic dogs; 95% CI 2.57-3.78%). The results of the risk factor analysis showed that thelaziosis in domestic dogs from Beijing was significantly correlated with regional distribution, seasonal distribution, country park travel history, and anthelmintic treatment history (p < 0.05). In summer and autumn, domestic dogs living in mountainous areas, with a history of country park travel and without deworming were 4.164, 2.382, and 1.438 times more infected with T. callipaeda than those living in plain areas without a history of country park travel and with a history of deworming (OR = 4.164, OR = 2.382, OR = 1.438, respectively). T. callipaeda-infected domestic dogs did not always show any ocular clinical symptoms, while symptomatic domestic dogs were mainly characterized by moderate symptoms. The results indicate that in summer and autumn, preventive anthelmintic treatment should be strengthened for domestic dogs with a country park travel history or those living in mountain areas. At the same time, we should be vigilant about taking domestic dogs to play in country parks or mountainous areas during summer and autumn because this may pose a potential risk of the owner being infected with T. callipaeda.

Thelazia callipaeda as a potential new threat to european wildcats: insights from an eco-epidemiological study

Global warming and displacement of vectors and wild and domestic hosts by humans greatly change host-parasite interactions and parasite transmission rates. Thelazia callipaeda Railliet and Henry, 1910 (Spirurida: Thelaziidae) is a zoonotic parasite rapidly colonizing Europe from its Asian native range. This nematode is vectored by Phortica flies and may cause ocular disorders, such as keratitis and corneal ulcers, in wild mammals, dogs, cats and humans. With the aim of detecting possible threats for the European wildcat (Felis silvestris) in one of its last Mediterranean strongholds, we initiated in 2017 a long-term monitoring program in Sierra Arana (southeastern Spain), which includes exploring its epidemiological and spatial relationships with domestic cats (Felis catus). During routine medical check-ups, we detected ocular nematodes in 3 of 17 (17.6%) wildcats and 1 of 23 (4.3%) domestic cats tested, confirmed to be T. callipaeda by microscopic and molecular analyses. This nematode species was first detected in the study area in 2021. To our knowledge, this is the first case of infection in wildcats in Spain. Through telemetry, we detected little spatial overlap between the home ranges of wildcats and domestic cats, which seems to be sufficient to facilitate the inter-specific transmission of T. callipaeda. Our findings suggest that this pathogen could be a new threat to the wildcat, a locally endangered wild felid. Further eco-epidemiological monitoring and sanitary control of domestic cats will be strongly needed, especially given the ongoing global warming scenario.

Canine ocular thelaziosis: first report in Andhra Pradesh

Thelaziosis is a vector-borne zoonotic disease with worldwide distribution, including in India and reports on canine ocular thelaziosis are very limited. The present case documentation will provide basic information to initiate the geographical epidemiological studies which will help to prevent the spread to these zoonotic diseases in the specified location. This communication reports about the rare case of canine ocular thelaziosis in Andhra Pradesh with the morphological features of the parasite and the management of ocular manifestations with suitable antimicrobial and anti-inflammatory eye drops along with ivermectin injections.

Zoonotic Thelazia callipaeda eyeworm in brown bears (Ursus arctos): A new host record in Europe

Thelazia callipaeda (Spirurida, Thelaziidae) eyeworm, a zoonotic parasite transmitted by lachryphagus drosophilids, causes subclinical to clinical ocular disease in a wide range of vertebrates, including humans. In the past 20 years, the infection spread primarily in areas where the vector thrives, and now is endemic in many European countries. Recently, this nematode has been reported also in the United States. Here, we describe the first record of the brown bear (Ursus arctos) as a host of T. callipaeda. Eight (26.7%) out of 30 bears were found to be infected with T. callipaeda adult worms. In addition, the parasite was detected in 13 wolves (Canis lupus) sharing the same environment with the brown bears. At the molecular characterization, all nematodes belonged to the haplotype 1, which is the only one recorded in Europe, as yet. This finding demonstrates that brown bears may act as hosts for this parasite, suggesting its potential role in the maintenance of the cycle not only in the wild but also in captivity. Under the above circumstances, the brown bear may represent a potential zoonotic risk for humans, both in rural and urban areas where other reservoirs may be infected.

Zoonotic Thelazia californiensis in dogs from New Mexico, USA, and a review of North American cases in animals and humans

Thelazia californiensis is a spirurid nematode found in the conjunctival sac of domestic and wild animals, including humans, across the western United States of America. Herein, we report two cases of thelaziosis by T. californiensis in dogs from New Mexico, United States, based on integrated morphological and molecular approaches. Nematode specimens collected from the conjunctiva of both dogs were identified as T. californiensis based on morphology. Our study substantially expands the knowledge on morphometry of this nematode species. Therefore, these data will be useful for accurate diagnosis of thelaziosis in domestic animals, wildlife and humans in North America, using classical, microscopy-based methods. We characterized for the first time the mitochondrial cytochrome c-oxidase subunit 1 (COI) and 12S genes of T. californiensis. While these markers support the validity of T. californiensis, they were not very informative for elucidating the phylogenetic relationships among Thelazia species. Nevertheless, the characterization of these diagnostic markers for T. californiensis will be useful for studies on the epidemiology, molecular xenomonitoring of fanniid vectors, and population genetics of this multi-host, zoonotic parasite.

Systematic review on infection and disease caused by Thelazia callipaeda in Europe: 2001-2020

Cases of thelaziosis by Thelazia callipaeda have been increasing considerably in Europe throughout the 21st century, with recent emphasis on Eastern Europe. A systematic review was conducted using defined search terms across three major databases and, additionally, with the examination of the references of the 56 articles selected. Available information about epidemiological and clinical features of all cases of thelaziosis by T. callipaeda in companion animals, wildlife and humans was extracted, evaluated and subjected to qualitative and quantitative analysis. In all cross-sectional studies about dogs, cats and red foxes, males were more frequently infected than females (dogs: p = 0.0365; cats: p = 0.0164; red foxes: p = 0.0082). Adult dogs seem to be more prone to infection (p < 0.0001), as well as large-sized dogs (p < 0.0001), and companion animals that live exclusively outdoors (p < 0.0001). Dogs and red foxes involved in these cross-sectional studies harboured significantly more female than male nematodes (p < 0.0001). Thelaziosis by T. callipaeda is far from controlled in Europe. Only through updated epidemiological data, knowledge improvement and awareness can correct diagnosis and appropriate treatment and prevention be ensured to tackle this zoonosis.

Canine thelaziosis in the Czech Republic: the northernmost autochthonous occurrence of the eye nematode Thelazia callipaeda Railliet et Henry, 1910 in Europe

The eye nematode Thelazia callipaeda Railliet et Henry, 1910 (Spirurida: Thelaziidae) is a vector-borne zoonotic nematode infecting a range of wild and domestic carnivores as well as humans. It is considered to be a causative agent of emerging and neglected disease and currently invades central part of Europe. Nematodes were collected from the eye of a dog living in Prague, which never travelled outside the Czech Republic. The nematodes were identified based on their morphology and partial sequence of the cox1 gene as T. callipaeda haplotype 1. This finding represents the northernmost record of autochthonous canine thelaziosis in Europe. The insufficient control of imported animals as well as free movement of dogs and wild carnivores within Europe probably facilitates spreading of T. callipaeda throughout the continent. To better understand the spreading of T. callipaeda and to prevent its zoonotic transmissions, information about the risk of this infection in newly invaded countries should be disseminated not only among veterinarians and physicians, but also within the community of pet owners and hunters.

Spain as a dispersion model for Thelazia callipaeda eyeworm in dogs in Europe

Thelazia callipaeda (Spirurida, Thelaziidae) causes ocular infection in carnivorous animals and humans. While growing numbers of companion dogs and sometimes cats are being diagnosed with thelaziosis, little is known about its real spread. As it has been also diagnosed in wild animals and human beings, it is considered a potential emerging zoonotic disease. This study provides information about the spread of the parasite in dogs in Spain since its initial description in 2010 until 2018. The first detection of T. callipaeda in the Principality of Andorra in 2017 is also reported. Two different studies were conducted: a) a survey in which clinical cases from veterinary practices were collected and b) a prevalence study in two endemic areas in western and central Spain (Site 1 La Vera region, Cáceres, and Site 2 El Escorial municipality, Madrid). In total, 1114 cases of thelaziosis were detected in 121 municipalities of Spain and 6 municipalities of Andorra. In 92 out these 127 municipalities, reports were of autochthonous cases. Six hundred twenty-three out of 1114 presented data collection sheet and were included in the statistical analysis: 510 cases identified by veterinarians in Spain and Andorra in Study 1, and 113 cases detected among the 234 dogs (48.3 %) examined in the prevalence study (Study 2). Prevalences were 61.3 % (84/137) for Cáceres and 29.9 % (29/97) for Madrid, being Site 1 significantly more risky (P <  0.0001, odds ratio: 3.72, CI: 2.14-4.47 %) compared to Site 2. Our study updates data for canine thelaziosis reported in the last decade in Spain and Andorra. Results highlight the urgent need for prevention strategies to control the spread of this potential zoonotic disease.

Thelaziosis due to Thelazia callipaeda in Europe in the 21st century-A review

Thelazia callipaeda was first described at the beginning of the 20th century in Asia, but this eyeworm is now frequently reported in Europe in the 21st century. To date, thelaziosis has been described in the following European countries (in order of appearance): Italy, France, Germany, Switzerland, Spain, Portugal, Belgium, Bosnia and Herzegovina, Croatia, Serbia, Romania, Greece, Bulgaria, Hungary, Slovakia, the United Kingdom, Turkey and Austria. The infected vertebrate host species include domestic carnivores (dogs and cats), wild carnivores (red foxes, wolves, beech martens, wildcats and golden jackals), lagomorphs (brown hares and wild European rabbits) and humans. In Europe, 11 cases of human thelaziosis have been reported, the majority of which are autochthonous. However, some of them have been imported, a fact which highlights the importance of surveillance policies to restrict cross-border spread of the parasite. The objectives of this article are to review key aspects of the epidemiology of T. callipaeda, summarise animal and human cases in Europe and emphasise the importance of education and awareness among veterinarians, physicians (particularly ophthalmologists) and animal, in order to owners to tackle this zoonosis.

Canine Ocular Thelaziosis in Slovakia a Case Report

Thelaziosis is a parasitic disease of the eye that has become more common in Europe over the last twenty years. It is caused by a nematode, order Spirurida, family Thelaziidae. The transmission of this parasite occurs by the dipteran flies. Thelazia callipaeda occurs in the conjunctival sac, under the third eyelid or in the lacrimal ducts, causing blepharospasm, conjunctivitis, keratitis and sometimes corneal ulceration. Thelaziosis is a zoonotic disease. It occurs in humans, domestic animals and wildlife. Between 2016 and 2018 three cases of canine ocular thelaziosis occurred in dogs admitted to the Small Animals Clinic in Kosice, Slovakia. In all cases, the systemic and local treatments were administered. The parasites were removed from the conjunctival sac. The identification of Thelazia callipaeda was performed by microscopic examinations.

The eyeworm Thelazia callipaeda in Portugal: Current status of infection in pets and wild mammals and case report in a beech marten (Martes foina)

Ocular thelaziosis is caused by nematodes of the genus Thelazia (Spirurida, Thelaziidae), which inhabit the surface of the eyes and associated tissues. Thelazia callipaeda affects a range of mammal species, including humans, and in the last two decades has been reported in multiple European countries, being classified as an emergent vector-borne pathogen. In Portugal T. callipaeda is endemic in north-eastern areas, where it has been reported in domestic dogs, cats, red foxes (Vulpes vulpes) and wild European rabbits (Oryctolagus cuniculus). We report, for the first time, T. callipaeda in a beech marten (Martes foina) from Portugal and highlight the presence of haplotype 1 as the only one found in Europe, irrespective of the host species and geographical area of provenience.

Three cases of imported eyeworm infection in dogs: a new threat for the United Kingdom

In July 2016 we described the first known case of canine ocular thelaziosis in the UK in a dog recently imported from Romania. Here we confirm our initial diagnosis using PCR followed by sequence analysis, and we report a further two clinical cases in dogs with recent history of travel to Italy and France. In view of the presence in the UK of the vector for Thelazia callipaeda, namely Phortica spp, we discuss the significance of these three cases in the context of the UK government’s pet travel scheme, disease control and both animal and public health in the UK.

First autochthonous cases of canine thelaziosis in Slovakia: a new affected area in Central Europe

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 cox1 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.

First autochthonous cases of canine thelaziosis in Slovakia: a new affected area in Central Europe

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 cox1 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.

The Increase of Exotic Zoonotic Helminth Infections: The Impact of Urbanization, Climate Change and Globalization

Zoonotic parasitic diseases are increasingly impacting human populations due to the effects of globalization, urbanization and climate change. Here we review the recent literature on the most important helminth zoonoses, including reports of incidence and prevalence. We discuss those helminth diseases which are increasing in endemic areas and consider their geographical spread into new regions within the framework of globalization, urbanization and climate change to determine the effect these variables are having on disease incidence, transmission and the associated challenges presented for public health initiatives, including control and elimination.

First report of canine ocular thelaziosis in the Muntenia Region, Romania

Ocular thelaziosis by Thelazia callipaeda is a vector-borne disease that infects domestic and wild carnivores as well as humans. In this paper, we present two cases of ocular thelaziosis in dogs that had never traveled outside Romania. Both presented with moderate conjunctivitis and ocular discharge. In total, 41 adult nematodes were removed from the conjunctival sacs of both dogs; these were identified via morphology as T. callipaeda. To the best of our knowledge, this is the first report of canine ocular thelaziosis caused by T. callipaeda from the Muntenia Region of Romania.

Thelazia callipaeda (Spirurida: Thelaziidae): first report in Greece and a case of canine infection

The eyeworm Thelazia callipaeda has been reported in different European countries, i.e. Italy, France, Germany, Switzerland, Spain, Portugal, Bosnia and Herzegovina, Croatia and Romania. The present article describes the first autochthonous case of ocular thelaziosis in a dog from Greece, thus revealing a new spot of infection in Europe. The dog in this case report, most likely infected at the northern borders of Greece, was referred to a private veterinary practice with conjunctivitis, oedema, keratitis, epiphora and mucoid discharge in both eyes. Seventy-seven nematodes were removed from both eyes, and the dog was treated with two subcutaneous injections of ivermectin 14 days apart, in combination with a topical antimicrobial medication. The parasites were morphologically and molecularly identified as T. callipaeda. Although in Greece there is no information about the presence and distribution of the fruit fly Phortica variegata, i.e. the intermediate host of T. callipaeda, the location where the dog was infected is environmentally suitable for its development. The present report of this zoonotic parasitosis indicates that in Greece, along with endemic areas in Spain and Italy, T. callipaeda is currently reaching its southernmost distribution limit in Europe.

A look into the Medical and Veterinary Entomology crystal ball

Medical and Veterinary Entomology (MVE) represents a leading periodical in its field and covers many aspects of the biology and control of insects, ticks, mites and other arthropods of medical and veterinary importance. Since the first issue of the journal, researchers working in both developed and developing countries have published in MVE, with direct impact on current knowledge in the field. An increasing number of articles dealing with the epidemiology and transmission of vector-borne pathogens have been published in MVE, reflecting rapid changes in vector distribution, pathogen transmission and host-arthropod interactions. This article represents a gaze into the crystal ball in which we identify areas of increasing interest, discuss the main changes that have occurred in the epidemiology of parasitic arthropods since the first issue of MVE, and predict the principal scientific topics that might arise in the next 25 years for scientists working in medical and veterinary entomology.

It shouldn't happen to a dog … or a veterinarian: clinical paradigms for canine vector-borne diseases

Canine vector-borne diseases (CVBDs) comprise a diverse group of viral, bacterial, protozoal, and helminth pathogens, transmitted predominantly by ticks and fleas, and cause significant health problems for dogs worldwide. Growing numbers of reports indicate that CVBDs are emerging in regions where they previously did not exist and this, combined with pathogens that are inherently difficult to detect, is providing companion animal veterinarians with some significant diagnostic challenges. This review discusses six paradigms concerning the diagnosis, treatment, prevention, and zoonotic implications of CVBDs from a veterinary clinical perspective.