Ocular Thelaziosis Research Articles

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.

Update on infections with Thelazia callipaeda in European wildlife and a report in a red fox, Vulpes vulpes, in Portugal

Thelazia callipaeda, also known as the “oriental eye worm”, is a zoonotic parasitic nematode with a wide range of hosts, particularly wild and domestic carnivores, but also lagomorphs and humans. Currently, ocular thelaziosis presents an expanding distribution range throughout Europe, including Portugal. This study provides an update on T. callipaeda infection reports (30 studies) in European wildlife comprising 54 host-locality records in 10 host species from nine European countries. The prevalence of T. callipaeda varied widely, with ranges from around 1% in red foxes and European hares to almost 50% in red foxes. The lowest mean intensity was 2.7 nematodes/host in European wildcats and the highest was 38.0 nematodes/host in wolves. In addition, a massive infection with T. callipaeda in a juvenile male red fox from eastern-central Portugal is also described, representing the southernmost report in a wild animal in this country. A total of 188 nematodes (139 females and 49 males) were collected from both eyes and were submitted to morphological and molecular characterization. Collected nematodes were morphologically identified as T. callipaeda. Given the endemicity of T. callipaeda in eastern-central Portugal, surveillance system should be implemented to monitor its presence among wild and domestic animals.

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.

First report of human Thelazia callipaeda infection in Portugal

The zoonotic parasitic nematode Thelazia callipaeda, also known as the oriental eye worm, is endemic in several European countries, including Portugal. Infections may result in ocular disease in domestic and wild animals as well as humans, with more or less severe manifestations. We report the first human case of ocular thelaziosis by T. callipaeda in Portugal, a country where the parasite had already been found to infect dogs, cats, red foxes, wild rabbits and a beech marten. An 80-year-old patient from east-central Portugal, who had been suffering from tearing for a few years, had whitish filiform fragments removed from the left eye. Polymerase chain reaction of partial cytochrome c oxidase subunit 1 and 18S small subunit rRNA genes followed by bidirectional sequencing and BLAST analysis confirmed T. callipaeda haplotype 1, the only haplotype previously reported in Europe. The endemicity of T. callipaeda in domestic and wild animals in east-central Portugal makes it very likely that infection of the human patient had occurred locally. In east-central and other geographical areas of Portugal, veterinarians and physicians, especially ophthalmologists, should regard T. callipaeda as a cause of ocular pathology in animals and humans.

Canine ocular thelaziosis from North East India.

Thelazia callipaeda is a vector borne zoonotic nematode transmitted by drosophilid flies of Phortica genus. It has been reported in humans from different parts of India including North Eastern region. Only one case of canine ocular thelaziosis has been reported from southern India while no case has yet been reported from the rest of the country. This communication reports the first case of canine ocular thelaziosis from Nagaland and the entire North East region of India along with the morphological characters and treatment.

The Vector-Borne Zoonotic Nematode Thelazia callipaeda in the Eastern Part of Europe, with a Clinical Case Report in a Dog in Poland

Thelazia callipaeda is a zoonotic nematode transmitted by drosophilid flies. It causes ocular thelaziosis, a disease of carnivores, such as dogs, cats, and foxes, and also humans. The parasite has thus far been observed in various areas of Eurasia, including 20 countries within Europe. The present study documents its presence in the south-east region of Poland, near the Ukraine border. An adult nematode was removed from the conjunctival sac of a dog showing ocular inflammation and purulent discharge. The dog’s precise origin is unknown. Based on its localization and morphometrical features, the nematode was identified as a Thelazia callipaeda adult male. The present study is the first report of T. callipaeda in a dog in Poland.

Update on the treatment and prevention of ocular thelaziosis (Thelazia callipaeda) in naturally infected dogs from Spain

This study examines the therapeutic and year-round prophylactic efficacy of different formulations used in dogs in three Spanish areas where canine thelaziosis is endemic. The study was conducted as a Good Clinical Practice, multicentre, randomised field study in privately owned outdoor dogs naturally infected with Thelazia callipaeda. The active pharmaceutical ingredients tested were: an oral formulation of milbemycin oxime 12.5 mg combined with praziquantel 125 mg (A), a subcutaneous sustained-release formulation of moxidectin 10 g (B), a moxidectin 2.5% weight/volume (w/v) spot-on formulation combined with imidacloprid 10% w/v (C), and an eye drop formulation (6 µg) of ivermectin 10 mg/ml diluted 10% in propylene glycol (D). Infected dogs were randomly allocated to treatment Groups A, B, C and D. Dogs testing negative for T. callipaeda inspection in two visits (Day 7/Day 14 and D30) were enrolled in the prophylaxis trial and reallocated to the corresponding study group (A, B, C or D). Treatment efficacy ranged from 70.4% recorded in Group A 1 week after treatment, to 100% recorded in Group C on Day 30 and in Group B on Day 60. Treatment was more efficacious in Group D (85.7% 1 week after treatment) than A, but was never 100% efficacious as in Groups B and C. Year-round prophylactic efficacy was 83.3% in Group A, 100% in Group B, 93.5% in Group C and 87.5% in Group D. In conclusion, products containing moxidectin were highly efficacious both in treating and preventing canine thelaziosis. Milbemycin also emerged as a good option. However, the off-label use of topical or subcutaneous ivermectin should be avoided due to possible adverse reactions such as pruritus, irritation or redness. In endemic areas, monthly prophylaxis to limit the spread of T. callipaeda to new areas across Europe and reduce zoonotic risks is essential.

First report of canine ocular thelaziosis in the Republic of Moldova

BackgroundCountries of eastern Europe are considered, due to several risk factors, more vulnerable to infections with newly (re)emerging pathogens. During the last decade, in several European countries, reports of autochthonous cases of ocular thelaziosis due to Thelazia callipaeda have been published, posing a great concern from both veterinary and public health perspective. However, in the Republic of Moldova only limited epidemiological data are available regarding zoonotic vector-borne pathogens and, until now, no data exist on the zoonotic nematode T. callipaeda.MethodsIn September 2018, an 11-year-old dog, mixed-breed, intact male was referred to a private veterinary clinic from Chișinău, Republic of Moldova, with a history of 2 weeks of an ocular condition affecting the right eye. The ophthalmological exam revealed the presence of nematode parasites in the conjunctival sac and under the third eyelid. The collected parasites were identified by morphological techniques and molecular analysis.ResultsA total of 7 nematodes were collected, and 5 females and 2 males of T. callipaeda were identified morphologically. The BLAST analysis confirmed the low genetic variability of this parasite in Europe. The travel history of the patient allowed us to confirm the autochthonous character of the case.ConclusionsTo the best of our knowledge, this is the first report of thelaziosis in dogs from the Republic of Moldova, which confirms the spreading trend of T. callipaeda and the existence of an autochthonous transmission cycle of this zoonotic parasite in the country.

Effectiveness of the spot-on combination of moxidectin and imidacloprid (Advocate\xae) in the treatment of ocular thelaziosis by Thelazia callipaeda in naturally infected cats

BackgroundThe present study evaluated the therapeutic effectiveness of moxidectin 1.0% (w/v) and imidacloprid 10% (w/v) (Advocate® spot-on solution for cats, Bayer Animal Health) against natural infections with the eyeworm Thelazia callipaeda in cats. This study was conducted as a GCP, negative-controlled, blinded and randomised field study in privately owned cats living in an area in southern Italy where T. callipaeda is enzootic.MethodsThe study was carried out in 30 cats (19 females and 11 males, aged from 8 months to 5 years, weighing 1.2–5.2 kg) of different breeds, naturally infected by T. callipaeda. At study inclusion (Day 0), animals were physically examined and the infection level was assessed by examination of both eyes for clinical score and live adult T. callipaeda count. Each cat was weighed and randomly assigned to one of the treatment groups (G1: Advocate, G2: untreated control). Clinical assessments and T. callipaeda adult counts were performed on Day 14. At the study completion visit on Day 28, clinical assessments and counts of T. callipaeda adults and larvae were performed. All cats were daily observed by their owners and general health conditions were recorded during the entire period of the study.ResultsThe primary effectiveness variable was the percentage of animals in G1 group (Advocate) showing a complete elimination (parasitological cure) of adult eye worms at Day 14 and Day 28 . The effectiveness of the treatment in the G1 group was 93.3 and 100% at Day 14 and Day 28 , respectively, when compared to group G2. Total worm count reduction from both eyes for Advocate was 96.3% on Day 14 and 100% on Day 28. Clinical data were confirmed by the examination of conjunctival pouch flushing. An overall reduction in the number of cats with lacrimation and conjunctivitis was observed following treatment despite the fact that in a few cats treated with Advocate clinical signs persisted due to the chronic nature of the disease.ConclusionsBased on the results of the present trial, a single dose of Advocate was found to be safe and highly effective in the treatment of natural T. callipaeda infection in cats.

Canine Ocular Thelaziosis in Slovakia a Case Report

Abstract 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.

Questionnaire-based survey on distribution of canine ocular thelaziosis in southwestern France

The distribution of Thelazia callipaeda, commonly known as “oriental eyeworm’’, has been considered for a long time to be confined to the former soviet Republics and Asia where the nematode causes infections in domestic and wild carnivores, rabbits and sometimes humans. However, since 2000, thelaziosis has been diagnosed in dogs and sometimes in cats from a growing number of European countries, including France. In 2006, a survey demonstrated that many autochthonous cases of canine thelaziosis were present in the department of Dordogne (southwestern France) in three hyperenzootic counties where strawberry production was predominant. The objective of the present study was to obtain an updated evaluation of the enzootic occurrence of T. callipaeda in France. In April 2016, an electronic questionnaire was sent to 1670 veterinary clinics from 24 French departments of southwestern France. Among 279 responses, 97 veterinary clinics reported cases of canine thelaziosis during the last 12 months. Most of them (72/97, 74.2%) reported a limited number of cases. Two veterinary clinics in previously-identified hyperenzootic counties of Dordogne reported the higher incidence (50 and 68 new cases annually). Noteworthly, two clinics located in another department (Landes) also reported many autochthonous cases (30 cases annually) demonstrating the existence of new enzootic foci. The present investigation confirmed that Dordogne is still an enzootic area of ocular thelaziosis and that the disease is spreading in new areas of southwestern France since a decade.

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.

Ocular thelaziosis in dogs and cats: good to keep an eye on

In the past decades the so-called ‘oriental eyeworm’, Thelazia callipaeda, has become endemic in various regions of Europe and, at the same time, non-endemic countries are currently at risk of introduction and establishment of an autochthonous life cycle. This drosophilid-transmitted nematode affects the eye and associated tissues of domestic animals (e.g. dogs, cats), wildlife and, sometimes, humans, thus posing a zoonotic hazard. Recently, therapeutic and prophylactic options have become available for controlling this parasitosis and minimising the risk of its spreading from endemic regions to areas that are presently free of the parasite. This article concisely reviews the current knowledge on T. callipaeda and its infection in companion animals, with a focus on practical and clinical aspects.

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...

Canine ocular thelaziosis produced by Thelazia callipaeda

Canine ocular thelaziosis produced by Thelazia callipaeda

Efficacy of moxidectin 2.5% and imidacloprid 10% in the treatment of ocular thelaziosis by Thelazia callipaeda in naturally infected dogs

Thelazia callipaeda (Spirurida, Thelaziidae) has been documented as agent of ocular infection in domestic animals (dogs and cats), wildlife (e.g., foxes, hares, rabbits), and humans. In the last two decades, this parasitosis has been increasingly reported in several European countries. Both adult and larval stages of the eyeworm are responsible for symptoms ranging from mild (e.g., lacrimation, ocular discharge, epiphora) to severe (e.g., conjunctivitis, keratitis, and corneal opacity or ulcers). The present study evaluated the clinical efficacy and safety of imidacloprid 10% and moxidectin 2.5% spot on (Advocate®, Bayer Animal Health) in comparison to milbemycin oxime/praziquantel tablets (Milbemax®, Novartis-Animal Health), as positive control, in the treatment of canine thelaziosis in naturally infected dogs and, a third group was used as an untreated control. Forty-seven dogs (27 females and 20 males) harbouring at least one live adult worm of T. callipaeda in one eye were enrolled from an endemic area of southern Italy. Each dog was then weighed and assigned in accordance with a random treatment allocation plan to one of the treatment groups (G1: imidacloprid 10% and moxidectin 2.5% spot on, G2: Untreated control and G3: milbemycin oxime/praziquantel tablets). On Day (D) 7, 14, 28 and 35 dogs were physically examined and the infection level was assessed by examination of both eyes, including conjunctival pouch and third eyelid for live adult T. callipaeda count and clinical scores. Dogs in G1 were treated on D0 and D28, whereas those in G3 on D0 and D7. Efficacy in G1 was 100% at each day post treatment (p<0.01). For the G3 group efficacy was 57.39% on D7 (p<0.05), 92.79% on D14 and 100% on D28 and D35 (p<0.01). The application of the spot on formulation moxidectin 2.5% and imidacloprid 10% was highly effective in the treatment of canine thelaziosis caused by T. callipaeda. Advocate® spot on can be recommended for the control of T. callipaeda infection, considering that this formulation is currently licensed in Europe for the treatment of a wide range of parasites affecting dogs.

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.

Serbia: Another endemic region for canine ocular thelaziosis

Canine thelaziosis is widely distributed in Far Eastern countries and considered endemic in many European countries, between latitudes 39' and 46' N. Because of the unique relationship between the causer and its intermediate and final hosts, the genus Thelazia is one of the most specialized nematodes in the taxon. Thelazia callipaeda (superfamily: Thelazioidea) infects the conjunctivas of several mammalians, including dogs and humans. Since dogs may also represent a reservoir of infection for humans, the aim of the study was to show the epidemiological situation of thelaziosis in dogs in the Republic of Serbia, after it was first diagnosed in 2014, which is crucial for the successful treatment, control, and prevention of the disease. The research was performed on privately owned dogs in the period from the end of April 2013 to the end of October 2015 in 7 different regions in Serbia. Adult parasites were mechanically removed from dogs with manifested ocular disorders, and thelaziosis was diagnosed in 178 out of 501 animals. The high prevalence of T. callipaeda in dogs (35.52%) in the analyzed areas of Serbia indicates the endemicity of eyeworm infestation in these areas.

Resolution of canine ocular thelaziosis in avermectin-sensitive Border Collies from Spain

Ocular thelaziosis by Thelazia callipaeda is an emerging disease that affects primarily dogs, but also cats, foxes and other wild carnivores, as well as humans. Three clinical cases of unilateral conjunctivitis caused by Thelazia nematodes were detected in Border Collie, a dog breed intolerant to the macrocyclic lactones. Animals came from southwestern Spain, on the border with Portugal. Eight worms were collected and identified molecularly as T. callipaeda by amplification and sequencing of partial cytochrome c oxidase subunit 1 gene. Oral treatment with mebendazole 20mg/kg (Telmin®) was effective in curing the infection.

Canine ocular thelaziosis caused by Thelazia callipaeda in Portugal

Ocular thelaziosis caused by Thelazia callipaeda is a vector-borne disease affecting dogs and humans. We report a case of thelaziosis in a 10-year-old German Shepherd dog from Vila Real city (Portugal). Ophthalmological examination revealed bulbar and nictitating membrane conjunctival hyperemia with serous discharge noted at the left medial canthus and blepharitis. Schirmer tear test value and intraocular pressure were within the reference ranges in both eyes, and biomicroscopy showed a transparent cornea without lesions or edema and no inflammatory reaction in the anterior chamber. No funduscopic alterations were detected by direct and indirect ophthalmoscopic examination. When testing the nasolacrimal patency, two white worms were observed on the caruncle conjunctival surface with undulating movements that increased with light intensity. In total, eight worms were collected and morphologically identified as T. callipaeda (seven mature females and one male). PCR amplification of a 689 sequence of partial cytochrome c oxidase subunit 1 target gene confirmed the nematodes were T. callipaeda, haplotype 1. The dog was treated with a single subcutaneous injection of ivermectin combined with additional topical application of ophthalmic fusidic acid drops and oral milbemycin oxime. One week after treatment, no worms were detected and the ocular clinical signs resolved. The most recent reports of canine thelaziosis in the Iberian Peninsula should alert local health authorities to the zoonotic potential of infestation with T. callipaeda, which should be included in the differential diagnosis of conjunctivitis in dogs and humans.