Canine Thelaziosis Research Articles

Eight cases of canine thelaziosis found in two localities in Korea.

Thelazia callipaeda, a parasitic nematode that causes thelaziosis in various mammals, including humans, is known to be endemic in Korea. However, life cycle-related information on the parasite, primarily from human infection and a few dog cases, is limited. This study reports additional cases of T. callipaeda infections in dogs from both rural and urban areas in Korea, indicating the potential for transmission to humans and other animals. We collected 61 worms from 8 infected dogs from Paju and Cheongju Cities and observed their morphological characteristics under a light microscope. The findings indicate that T. callipaeda infections in animals in Korea may be underestimated and are distributed close to human environments. Our results contribute to the growing knowledge of the reservoir hosts of T. callipaeda in Korea and highlight the importance of continued surveillance and research to prevent and control this emerging zoonotic disease.

Thelaziosis caused by <i>Thelazia callipaeda</i> Railliet et Henry, 1910 (literature review)

The purpose of the researchis to analyze literature data on epizootology, morphology and biology ofThelazia callipaeda, and on clinical signs of thelaziosis.Thelaziosis caused byTh. callipaedais widespread and not limited to Southeast Asian countries. At the end of the last century, autochtonous infection cases of thelaziosis were noted in Italy, and later the disease was recorded in France, Switzerland, Germany, Spain, Belgium, Portugal, Romania, Bosnia, Herzegovina, Croatia, Greece, Slovakia, Serbia, Turkey, Hungary, Moldova, Austria, Czech Republic, Poland, etc. Cases of thelaziosis recorded in the United States of America and the Russian Federation were most likely allochthonous and imported from contaminated areas. In Russia, canine thelaziosis was recorded in Moscow, St. Petersburg and Tyumen. It was found that definitive hosts ofTh. callipaedawere not only cats, dogs or humans, but also many species of wild animals, namely, gray wolf, red fox, pine marten, hare, wild cat, Iberian wolf, European grey rabbit, beech marten, pine marten, golden jackal, European badger and brown bear. The prevalence of Thelazia infection among populations of wild animals reached 38.1%. The maximum number of helminths found in one animal was 96 specimens. In the life cycle ofTh. callipaeda, males of the fruit flyPhortica variegataandPh. okadai, which can keep Thelazia larvae in their bodies for up to 180 days are involved. Phylogenetic analysis of the cox1 gene showed thatTh. callipaedaisolated from diseased animals in different countries belonged to haplotype-1, which was common in Europe.

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.

Thelazia callipaeda in Slovakia - From sporadic cases to endemic areas.

Spirurid nematode Thelazia callipaeda, transmitted by the fruit fly Phortica variegata, is a causative agent of an ocular parasitic disease called also canine thelaziosis. Dogs, cats, and wild canids are considered the primary definitive hosts for the parasite, but humans may also serve as aberrant definitive hosts. For long decades the geographic range of T. callipaeda was strictly limited to the territory of Asia, but after the year 2000, the parasite began to spread rapidly through Europe. The first autochthonous infections of dogs and foxes in Slovakia were recorded in 2016. In the present study, the results of a whole-area surveillance for canine thelaziosis are reported. Altogether, 142 cases of infection caused by T. callipaeda were diagnosed by veterinarians in dogs between 2016 and the first quarter of 2021, and two cases of feline thelaziosis were recorded. The majority of the dogs showed mild ocular signs manifested by conjunctivitis; 8.5% of them suffered from more serious mucopurulent discharge, and in two dogs corneal ulceration was recorded. The screening revealed increasing trends in the occurrence of canine thelaziosis from both a temporal and spatial point of view and unambiguously confirms the endemic status of T. callipaeda in Slovakia with the prospect of its further expansion.

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.

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.

Temperature is a common climatic descriptor of lachryphagous activity period in Phortica variegata (Diptera: Drosophilidae) from multiple geographical locations

BackgroundThe drosophilid Phortica variegata is known as vector of Thelazia callipaeda, the oriental eyeworm native to Asia that has become an emergent zoonotic agent in several European regions. Unlike almost all other arthropod vectors of pathogens, only P. variegata males feed of lachrymal secretions of animals, ingesting first-stage larvae (L1) of the worm living in the orbital cavities of the host, and allowing with the same behaviour the introduction of infective L3. Despite the increased detection of T. callipaeda in many European countries, information about the length of the lachryphagous activity period of P. variegata and a deep knowledge of the environmental and climatic variables involved are still limited.MethodsWe herein present the results of a multicentre study involving five sites from four different countries (Italy, Spain, UK and USA) where canine thelaziosis is endemic and/or where it has already been ascertained the presence of P. variegata. Field data have been obtained on a fortnightly basis from mid-April to the end of November 2018 from a contemporary standardized sampling (same sampling effort and time of collection in all sites) of lachryphagous flies collected around the eyes of a human bait using an entomological net. These data have been associated to data collection of local climatic variables (day length, temperature, wind speed, barometric pressure and relative humidity).ResultsOverall, a total of 4862 P. variegata flies (4637 males and 224 females) were collected, with high differences in densities among the different sampling sites. Significant positive correlations were found between P. variegata male density and temperature and wind speed, while negative correlations were observed for barometric pressure and relative humidity. However, the above significant differences are confirmed in each sampling site separately only for the temperature.ConclusionsThis multicentre study highlights that temperature is the major common environmental driver in describing the lachryphagous activity of P. variegata in Europe and USA and, therefore, the transmission risk of thelaziosis.

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.

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.

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.

Detection of Thelazia callipaeda in Phortica variegata and spread of canine thelaziosis to new areas in Spain

BackgroundThe fruit fly Phortica variegata (Drosophilidae: Steganinae) feeds on the ocular secretions of animals and humans, and has been described as an intermediate host of the eye worm Thelazia callipaeda (Spirurida: Thelaziidae) in Italy. Despite the increased detection of T. callipaeda in many European countries, information about its vector role in natural conditions is still limited. In the Iberian Peninsula, thelaziosis caused by T. callipaeda has been reported in dogs, cats, red foxes, wild rabbits and humans.MethodsIn the last seven years, we have detected increased numbers of cases of canine thelaziosis at three locations in mainland Spain: Site 1, La Vera region (Cáceres Province, central-western Spain; 51 cases); Site 2, El Escorial municipality (Madrid Community, central Spain; 23 cases); and Site 3, Miraflores de la Sierra municipality (Madrid Community, central Spain; 41 cases). Site 1 is considered endemic for T. callipaeda while the other two sites have been recently recognised as risk zones for T. callipaeda infection.ResultsFrom June 2016 to September 2017, 2162 flies were collected and morphologically identified as Phortica spp. (Site 1, n = 395; Site 2, n = 1544; and Site 3, n = 223). Upon dissection, third-stage T. callipaeda larvae were found in two out of 155 flies examined from Site 1, and both these larvae tested molecularly positive for the eye worm. Of the 395 flies collected from Site 1, 371 were molecularly processed for arthropod species identification and T. callipaeda detection. All 371 flies were identified as P. variegata and 28 (7.5%; 95% CI: 4.8–10%) tested positive for T. callipaeda DNA haplotype 1.ConclusionsOur findings indicate that T. callipaeda circulates among dogs and P. variegata in Spain, where zoonotic cases have been also reported. The co-existence of canine thelaziosis and Phortica spp. in geographical areas previously considered free of the eye worm indicates a risk of infection for both animals and humans living in this region.

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.

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...

Spreading of Thelazia callipaeda in Greece.

Thelazia callipaeda (Spirurida, Thelaziidae), the so-called oriental eyeworm, has been increasingly reported as an agent of infection in animals and humans from many European countries. Clinical signs range from subclinical to moderate or severe ocular disorders (e.g., epiphora, photophobia, conjunctivitis, keratitis, ulcers). The disease has been also diagnosed in animals from countries of the Balkan area (e.g., Croatia, Bosnia and Herzegovina and Serbia), but only a single case of canine thelaziosis, presumably autochthonous, was reported in Northern Greece. In this study, we provide robust information of the occurrence of thelaziosis in Greece by reporting autochthonous cases of thelaziosis in dogs (n=46), cats (n=3) and in one rabbit (Oryctolagus cuniculus) living in Northern and Central regions of Greece. The occurrence of a single haplotype of the cytochrome oxidase subunit 1 gene confirms that the same zoonotic haplotype of the parasite circulating in Europe is also spreading in Greece. The increased awareness of this parasitosis is crucial to limit the risk of further infections in both humans and animals in European countries.

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.

Canine and Feline Thelaziosis Caused by Thelazia Callipaeda in Serbia

Abstract Thelazia callipaeda is a parasitic nematode causing ocular infections in different mammalian species and humans, clinically manifested as lacrimation, conjunctivitis, keratitis, corneal opacity or corneal ulcer. In this paper, we reported six cases of autochthonous canine and feline thelaziosis on different localities in Serbia. Total of 285 parasites (85 males and 200 females) were collected from the eyes of infected animals (n=6) suffering from uni- or bilateral conjunctivitis, with the number of parasites ranging from 7 to 150 per animal. All parasites were morphologically identified as T. callipaeda, while molecular analyses of cytochrome oxidase 1 (cox1) gene revealed the presence of h1 haplotype, as the unique previously reported in other studies in Europe. Since T. callipaeda is a newly detected parasite in Serbia with the infective potential for humans, there is a necessity for animal owners education and cooperation among professional services in order to control this zoonosis.

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.