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

Efficacy of a combination of esafoxolaner, eprinomectin and praziquantel (NexGard® Combo) against Thelazia callipaeda in naturally infected cats

This clinical study assessed the efficacy of a topical combination of esafoxolaner, eprinomectin and praziquantel (NexGard® Combo) in treating cats naturally infected with the eyeworm Thelazia callipaeda (Nematoda, Thelaziidae). On Study Day (SD) 0, sixteen client-owned cats with eyeworm infection were allocated to an untreated control group (G1, 8 cats) or to a NexGard® Combo treated group (G2, 8 cats) and subjected to ocular examination. Cats in G2 received the treatment as per label recommendations. On SD 7 and 14 (±1), cats were examined for the presence of eyeworms and clinical signs. On SD 14, eyeworms were collected and counted. On SD 7 and 14, all cats in G1 were still infected with eyeworms, while G2 cats were free from eyeworms on SD 7 and 14, demonstrating 100% efficacy (p < 0.0001). All collected eyeworms were morphologically and molecularly confirmed to be T. callipaeda. On SD 0, fifteen out of the sixteen cats (7 in G1 and 8 in G2) displayed inflammatory ocular signs. On SD 7, all eight untreated cats and seven treated cats displayed inflammatory ocular signs. On SD 14, five out of eight G2 treated cats had recovered, while the eight untreated cats still displayed inflammatory ocular signs. The treatment significantly reduced lacrimation and conjunctivitis (p = 0.0001). No adverse reactions occurred. This clinical study provides evidence that NexGard® Combo is highly safe and effective for the treatment of T. callipaeda infection in cats under field conditions.

Occurrence of Thelazia callipaeda and its vector Phortica variegata in Austria and South Tyrol, Italy, and a global comparison by phylogenetic network analysis

The zoonotic nematode Thelazia callipaeda infects the eyes of domestic and wild animals and uses canids as primary hosts. It was originally described in Asia, but in the last 20 years it has been reported in many European countries, where it is mainly transmitted by the drosophilid fruit fly Phortica variegata. We report the autochthonous occurrence of T. callipaeda and its vector P. variegata in Austria. Nematodes were collected from clinical cases and fruit flies were caught using traps, netting, and from the conjunctival sac of one dog. Fruit flies and nematodes were morphologically identified and a section of the mitochondrial cytochrome c oxidase subunit I gene (COI) was analysed. A DNA haplotype network was calculated to visualize the relation of the obtained COI sequences to published sequences. Additionally, Phortica spp. were screened for the presence of DNA of T. callipaeda by polymerase chain reaction. Thelazia callipaeda and P. variegata were identified in Burgenland, Lower Austria, and Styria. Thelazia callipaeda was also documented in Vienna and P. variegata in Upper Austria and South Tyrol, Italy. All T. callipaeda corresponded to haplotype 1. Twenty-two different haplotypes of P. variegata were identified in the fruit flies. One sequence was distinctly different from those of Phortica variegata and was more closely related to those of Phortica chi and Phortica okadai. Thelazia callipaeda could not be detected in any of the Phortica specimens.

Feline thelaziosis (Thelazia callipaeda) in Spain: state-of-the-art and first prophylactic trial in cats

OBJECTIVES

Thelaziosis caused by the nematode Thelazia callipaeda (Spirurida, Thelaziidae) affects the eyes of domestic and wild carnivores, lagomorphs and even humans. The role of cats in spreading thelaziosis remains unclear. The present study assesses the current status of feline T callipaeda infection in Spain and presents the results of the first prophylactic trial conducted in this species.

METHODS

We retrospectively analysed the occurrence of feline thelaziosis (study 1), examined its prevalence based on cross-sectional sampling of endemic areas (study 2), and assessed the therapeutic/prophylactic benefits of a spot-on (moxidectin) and therapeutic efficacy of an eye drop (ivermectin) formulation (study 3).

RESULTS

In study 1, 69 Thelazia-infected cats were examined. Autochthonous cases were detected in 18/26 municipalities surveyed in Spain, which corresponds to 88.4% (n = 61/69) of the total number of cases. In study 2, 74 cats (20 from La Vera region and 54 from Orense province) were examined from 2011 to 2013. Ten of these cats (13.5%) were infected with T callipaeda. The infection prevalence was 40% (n = 8/20) in La Vera and 3.7% (n = 2/54) in Orense. The therapeutic efficacy of ivermectin was assessed over a summer (2011) in 12 cats, while that of moxidectin was examined over a 17-month period in seven cats. Four of these seven cats were subsequently included in an all-year-round prophylaxis trial. Treatment efficacy ranged from 91.7% (ivermectin) on day 28 after treatment to 100% (moxidectin) on day 14. Moxidectin prevented reinfections in cats.

CONCLUSIONS AND RELEVANCE

Our data confirm the endemic status of T callipaeda infection in Spain, revealing its high prevalence in cats living in known endemic areas. Moxidectin was effective in treating and preventing infection. We strongly recommend the inclusion of thelaziosis in the differential diagnosis of pets and humans presenting with ocular manifestations, along with adequate preventive measures.

Efficacy of fipronil/(S)-methoprene/eprinomectin/praziquantel (Broadline®) against Thelazia callipaeda in naturally infected cats

Background

The present clinical field trial was conducted to assess the efficacy of a broad-spectrum parasiticide spot-on formulation containing eprinomectin (Broadline^®) against Thelazia callipaeda eyeworm in naturally infected cats.

Methods

Fifteen privately owned cats harboring at least one live adult T. callipaeda were included in the study. Cats were randomly allocated to an untreated control group of seven cats or to a Broadline^®-treated group of eight cats. Cats were treated on Day 0; ocular examinations were performed at inclusion and on Days 7 and 14; eyeworms were recovered and counted on Day 14. The primary efficacy assessment was based on group comparison of number of T. callipaeda on Day 14.

Results

Seven days after treatment, six of eight treated cats were negative for eyeworm infection per visual examination, and on Day 14 no eyeworms were found in the treated cats while the seven untreated cats were still infected (geometric mean: 1.97). All cats had inflammatory ocular signs at inclusion; on Day 14, five of eight treated cats had recovered while all untreated control cats were still symptomatic. All collected parasites were confirmed to be T. callipaeda by morphology and molecular characterization.

Conclusions

A single treatment with Broadline^® provided 100% efficacy against feline thelaziosis and improved related ocular inflammation signs.

Graphical abstract

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.

Ophthalmic Thelazia callipaeda infections: first feline and new canine imported cases in Germany

The first case of feline ocular Thelazia callipaeda infection and two new canine imported infections in West Germany are here described. The three animals had a history of recent travel to/from other countries. The young adult cat imported from Spain presented an intermittent unilateral ocular discharge. During in-depth ophthalmic examination, a single alive nematode was removed from the conjunctival compartment of the affected eye. Referring to the canine cases, an adult female dog originated from Kenya presented epiphora and mucous whitish-grey discharge of the right eye. During flushing of the nasolacrimal duct two small, thin and long nematodes were removed. Furthermore, a male Borzoi racing dog with regular visit to racing tracks in different countries presented ocular mucous discharge. At ophthalmologic examination, two transparent-whitish vital nematodes were removed. All nematode specimens of the three cases were morphologically identified as adult T. callipaeda parasites. The animals were treated orally with milbemycin oxime (2.0 mg/kg; cat) or milbemycin oxime/praziquantel (0.5 mg/kg and 5.0 mg/kg; dogs) twice with 1-week interval resulting in complete resolution of symptoms. The repeated introduction of patent T. callipaeda-infected animals, especially from southern and eastern endemic countries, will ease the establishment of ophthalmic thelaziosis in Northern Europe. The male fruit fly, Phortica variegata, an intermediate host of T. callipaeda, is endemic within European countries. Considering the clinical and zoonotic relevance of ophthalmic thelaziosis, enhanced disease awareness of European medical and veterinarian doctors and in-depth eye examination for proper detection of T. callipaeda are crucial for appropriate anthelmintic treatments and to limit spreading of the infection.

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.

The first autochthonous case of feline ocular thelaziosis in Austria

Over the last 30 years, Thelazia callipaeda (Spirurida: Thelaziidae) has increasingly been reported as an agent of ocular infections in animals and humans throughout Europe. Following the cases of canine ocular thelaziosis recently recorded in Austria for the first time, in the present paper, we describe the first case of T. callipaeda infection in an Austrian cat with no history of traveling abroad. This finding further supports the occurrence of the parasite’s autochthonous transmission cycle in the country. The cat showed serous ocular discharge, conjunctival hyperemia, and mild conjunctival edema in the right eye. Mechanical removal of the parasite from the cat’s eye, in combination with milbemycin oxime/praziquantel oral treatment and topical use of tobramycin/dexamethasone eye drops led to complete resolution of the clinical signs within 2 weeks. Results presented in the current study are of great importance for the local veterinarians who seemed largely unaware of this zoonotic parasite. Therefore, increased awareness of medical and veterinary communities is imperative for preventing further infections in both animals and humans.