Echinocephalus inserratus sp. n. (Nematoda: Gnathostomatidae) from the stingray Pastinachus ater (Dasyatidae) and new records of congeneric and some other nematode larvae from teleost fishes off New Caledonia.

Based on light and electron microscopical studies, a new nematode parasite, Echinocephalus inserratus sp. n. (Spirurida: Gnathostomatidae), is described from the spiral valve of the broad cowtail stingray Pastinachus ater (Macleay) (Dasyatidae, Myliobatiformes) from off New Caledonia. The new species is morphologically and biometrically most similar to Echinocephalus overstreeti Deardorff et Ko, 1983, differing from it mainly in the absence of serrations on the posterior parts of pseudolabia and on interlabia, and in having a longer gubernaculum (150-299 µm long). Morphologically unidentifiable, mostly encapsulated larvae of Echinocephalus spp. were recorded from the following six species of teleost fishes collected in New Caledonian waters, serving as paratenic hosts: Perciformes: Acanthopagrus berda (Forsskål) (Sparidae) and Nemipterus furcosus (Valenciennes) (Nemipteridae); Tetraodontiformes: Abalistes stellatus (Anonymous), Pseudobalistes fuscus (Bloch et Schneider) (both Balistidae), Lagocephalus sceleratus (Gmelin) (Tetraodontidae) and Aluterus monoceros (Linnaeus) (Monacanthidae). Co-parasitising larvae of Ascarophis sp. and Hysterothylacium sp. were also collected from P. fuscus. All these findings represent new host and geographical records. A key to valid species of Echinocephalus Molin, 1858 is provided.

Morphological and molecular characterization of Spirocerca lupi (Nematoda: Spirocercidae) from domestic dogs in Vietnam with reference to Spirocerca vulpis.

Spirocerca lupi is a common parasitic nematode associated with esophageal cancer of canids. Recent surveys have revealed an increasing number of canids infected with Spirocerca spp. in Africa, the Americas, Europe and Western Asia, and described a new species, Spirocerca vulpis, from red foxes (Vulpes vulpes). However, in Southeast Asia, research on Spirocerca spp. is scarce. Therefore, the aim of this study is to explore Spirocerca infection in domestic dogs in Vietnam and to identify the Spirocerca species by analyzing their morphometric and molecular data. We found Spirocerca spp. specimens in 51 (17.7%) out of 287 dogs examined with the intensity of infection ranging from one to 29 nematodes per dog. These nematodes were morphologically and molecularly identified as S. lupi. For morphology, the presence/absence of teeth, the ratio of glandular to muscular esophagus lengths, and the position of the vulva opening of S. lupi and S. vulpis varied between reports, suggesting caution in identification of Spirocerca species based exclusively on morphological characteristics. The molecular analysis based on a partial cox1 sequence revealed that S. lupi from Vietnam is genetically close to those from India and China, but far different from those of Israel, South Africa, Peru and Hungary. Given high genetic and morphological variations, more extensive surveys on Spirocerca spp. from various mammalian hosts at a greater scale are necessary to elucidate the divergence of this nematode.

Prevention of canine ocular thelaziosis (Thelazia callipaeda) with a combination of milbemycin oxime and afoxolaner (Nexgard Spectra®) in endemic areas in France and Spain.

In the past decade, canine thelaziosis due to Thelazia callipaeda has been diagnosed in an increasing number of European countries, with endemic areas being identified. A multi-center field trial was conducted in endemic areas in France and Spain to evaluate the efficacy of monthly administrations of the oral milbemycin oxime/afoxolaner combination (NexGard Spectra®) for the prevention of T. callipaeda infection in at-risk dogs. A total of 79 dogs negative for T. callipaeda and with a clinical history of eyeworm infection in the past two years completed the study. Dogs were randomly allocated either to a negative control group (42 dogs) or to the NexGard Spectra® treated group (37 dogs). All dogs were followed up for a 6-month period and assessed monthly for the presence of nematodes on the eyes and for the signs of ocular thelaziosis (e.g., conjunctivitis, keratitis, and ocular discharge). When the presence of nematodes was confirmed, the conjunctival fornix was flushed with a saline solution for parasite recovery and counting, and the dogs were treated appropriately. Recovered parasites were stored in 70% alcohol for subsequent morphological identification. During the course of the study, 57.1% (24/42) of the control dogs were diagnosed positive for Thelazia infection, which illustrates a high incidence rate of parasite infection. Conversely, no eyeworm was recovered from any of the 37 dogs that received NexGard Spectra®. All parasites sampled were confirmed to be T. callipaeda. This clinical field study demonstrated that monthly administrations of NexGard Spectra® provided 100% preventive efficacy against canine thelaziosis.

Redescription of Rhabdochona papuanensis (Nematoda: Thelazioidea), a parasite of rainbow fishes (Melanotaenia spp.); the first record of the species of Rhabdochona in Australia.

Numerous specimens of the parasitic nematode Rhabdochona papuanensis Moravec, Riha et Kuchta, 2008 (Spirurida: Rhabdochonidae) were collected from the intestines of the Australian endemic freshwater fish (eastern rainbow fish) Melanotaenia splendida (Peters) (Melanotaeniidae, Atheriniformes) in the Behana Creek, North Queesland during November of 2015. Although many species of Rhabdochona Railliet, 1916 are known to be common parasites of fishes in other continents, the present finding of R. papuanensis represents the first record of the species belonging to this genus from the Australian mainland. Light and scanning electron microscopical examinations of these newly collected specimens made it possible to redescribe in detail this nematode species, originally incompletely described from a congeneric host in Papua New Guinea. Fully developed, filamented eggs of R. papuanensis and the conspecific fourth-stage larva are described for the first time. The present finding of R. papuanensis in M. splendida from Australia represents new host and geographical records.

Eyeworm infections in dogs and in a human patient in Serbia: A One Health approach is needed.

Thelazia callipaeda eyeworm has been frequently reported parasitizing humans in Asia. In Europe, the parasite is endemic in wild and domestic carnivores and only eight cases have been reported in humans so far. We describe the first case of human thelaziosis in Serbia, along with two cases in dogs from the same area. A One Health approach, based on cooperation amongst veterinarians and physicians, is strongly advised for this emerging infection in order to assess the risk for and prevent of the zoonotic infection.

Thelazia rhodesii infection on cattle in Kupang district.

A cross-sectional study was carried out to determine the prevalence, the intensity, infection, clinical sign, to identify species and to investigate associated risk factors of thelaziosis in cattle in Kupang district, Nusa Tenggara Timur Province. A total of 385 head of cattle were randomly selected from 96 farms in three subdistricts of Kupang District and observed for thelaziosis. The nematode present in the eye of cattle were collected with a forcep after administering local anesthesia (10% Xylocaine). The potential risk factors related to age of cattle, human resources and farm management were obtained by interviewing the farmers. Logistic regression was applied to analyze related risk factor of thelaziosis. The result showed that of the total 385 cattle observed, 23 (5.96%) were infected by Thelazia spp., of which 22 cattle showed apparent clinical signs namely excessive lacrimation and conjunctivitis that led to keratoconjunctivitis, while one cattle showed ulceration. A total of 357 worms (157 males and 210 female) were collected from 23 infected cattle with the mean number of worms in infected cattle being 32.92 ± 21.03. Observations on morphological characteristics using Scanning Electron Microscope (SEM) helped to identify the nematode species as Thelazia rhodesii. The infection was more prevalent in older cattle (≥ 6-12 month old) than calves (0-6 month old) (P<0.05). Significant risk factors of animal husbandry practices affecting the prevalence of thelaziosis in cattle were anthelmintic treatment, grazing management, barn cleaning, and manure management. Our results highlight that significant risk factors of the disease should be considered in designing strategic control programs for thelaziosis.

Morphological differentiation among three Thelazia species (Nematoda: Thelaziidae) by scanning electron microscopy.

Thelaziasis is an ocular infection of several mammals caused by nematodes of the genus Thelazia (Spirurida, Thelaziidae). The adults live in the lachrymal ducts and conjunctival sacs of infected animals, and transmission occurs by means of different species of muscids. T. rhodesi, T. skrjabini, and T. gulosa affect mainly cattle, inducing conjunctivitis, keratitis, and ocular discharge. This article describes the morphological features of adult T. rhodesi, T. skrjabini, and T. gulosa by scanning electron microscopy and highlights the most relevant differences for their identification.

Fine structure of body surface of Thelazia skrjabini (Nematoda: Spirurida, Thelaziidae).

Thelazia skrjabini (Spirurida, Thelaziidae) is a parasite of cattle that causes ocular infections. Scanning electron microscopy was used to study the surface ultrastructure of adult worms of this nematode. At the anterior end of both sexes, the buccal opening was orbicular. Around the mouth, two circles of cephalic papillae were seen: the inner circle with six papillae and the outer circle with four submedian papillae. At both lateral sides of the head, two amphids were observed. A pair of lateral cervical papillae was present. In the female, the vulva was located at the anterior part of the body and the tail carried an anal pore and two phasmids near the tip. In the male, the tail was blunt without caudal alae and curved ventrally. There were 31 to 38 unpaired preanal papillae, two paired postanal papillae, and two phasmids at the posterior end. The cuticle had fine, scarcely visible transversally striations. At the anterior end of the two cases, one abnormal mass was seen.

Thelazia rhodesi (Spirurida, Thelaziidae), bovine eyeworm: morphological study by scanning electron microscopy.

Thelazia rhodesi (Spirurida, Thelaziidae) is a parasite of ruminants, which causes ocular infections. Scanning electron microscopy was used to study the surface ultrastructure of adult worms of this nematode. At the anterior end of both sexes, the buccal opening was orbicular. Around the mouth, four pairs of cephalic papillae and two lateral amphids were seen. A pair of lateral cervical papillae was present. In the female, the vulva was located at the anterior part of the body, and the tail end was stumpy with two phasmids near its extremity. In the male, the tail was blunt, without caudal alae, and curved ventrally. There were 14 paired preanal papillae, one single papilla directly anterior to cloaca, one paired postanal papilla, and two phasmids at the posterior end. The spicules were unequal and dissimilar. The cuticle was transversally striated and appeared serrated.

Ultrastructural observations on the surface of Thelazia lacrymalis (Nematoda: Spirurida, Thelaziidae).

Scanning electron microscopy (SEM) was used to study the surface ultrastructure of female Thelazia lacrymalis obtained from naturally infected cattle. At the anterior end, the buccal capsule was cup shaped. The mouth was without lips and was surrounded by four cephalic papillae and two amphids. There were two lateral cervical papillae. Also, a single small papilla was seen on the ventral side, close to the vulvar opening. The vulva was located posterior to the end of the oesophagus and the tail carried an anal pore and a pair of phasmids near the tip. The cuticle was transversally annulated with fine striations.

Scanning electron microscopic observations on adult Spirocerca lupi (Nematoda: Spirurida, Thelaziidae).

Scanning electron microscopy was used to study the surface ultrastructure of adult worms of Spirocerca lupi. At the anterior end of both sexes, the mouth is hexagonal, without definite lips. Around the mouth, two pairs of submedian cephalic papillae and two lateral amphids are present. There is a pair of lateral cervical papillae. At the anterior end of the body, on the ventral side, an excretory pore is seen. In the female, the vulva is located anteriorly and the tail is blunt, with a pair of subterminal phasmids. The male tail is spiral, with four pairs of preanal papillae, a single large median preanal papilla on the anterior lip of the cloacal aperture, two pairs of postanal papillae, four pairs of tiny papillae near the tip of the tail and two subterminal phasmids. The cuticle shows an abnormal tumour-like mass in two cases.

Embryogenesis and the first-stage larva of Thelazia lacrymalis.

The female reproductive system of Thelazia lacrymalis (Nematoda: Thelaziidae) was investigated by light and scanning electron microscopy (SEM) with regard to the developmental stages and the stage deposited by the gravid nematode. Female T. lacrymalis have a didelphic and opisthodelphic type of reproductive system with paired ovaries, oviducts and uteri and a single vagina and vulva. Round and spindle-shaped primary oocytes are documented within the ovaries and oviducts, respectively. The distal part of each uterus provides a fertilization chamber filled with spermatozoa, followed by a sphincter-like part. Further anterior, the uteri broaden gradually containing dividing zygotes, small and large morulae, tadpole-stage embryos and horseshoe-shaped embryos which increase in length and become slimmer forming pretzel-stage embryos and larvae rolled up. The larvae stretch gradually and finally lie straight but still covered with their egg membrane in the vagina. The egg membrane encloses the whole larva and is enlarged at the pointed tail of the larva forming a bulb. At the SEM level, the first-stage larva is shown to have a terminal mouth and three hooks directed posteriorly and a striated cuticle. As morphologically identical larvae were also found in lavages of the conjunctival sac of horses infected with T. lacrymalis, this nematode species can be described as ovoviviparous.

Ephemera strigata (Insecta: Ephemeroptera: Ephemeridae) is the intermediate host of the nematodes Rhabdochona denudata honshuensis and Rhabdochona coronacauda in Japan.

Juvenile freshwater parasitic nematodes Rhabdochona denudata honshuensis Moravec and Nagasawa, 1989 and Rhabdochona coronacauda Belouss, 1965 (Spirurida: Thelazioidea: Rhabdochonidae) were found in mayfly nymphs collected in a mountain stream in Japan. Considering the relative density of mayfly nymphs, nematode prevalence, and intensity of parasitism, Ephemera strigata Eaton and Potamanthus formosus Ulmer (Ephemeroptera: Ephemeridae) are frequent natural intermediate hosts for R. d. honshuensis in this locality. The intermediate host of R. coronacauda also is the E. strigata nymph.

Thelazia callipaeda (Spirurida, Thelaziidae) of carnivores and humans: morphological study by light and scanning electron microscopy.

Thelazia nematodes cause ocular infection in several mammals and are transmitted by dipteran flies. Thelazia callipaeda Railliet and Henry 1910 (Spirurida, Thelaziidae) is common in the Far East, where it causes eyeworm infection in carnivores and humans. In the past few years, it has also been reported in dogs, cats and foxes in Northern and Southern Italy. Although a great deal of work has been carried out in China and other Eastern countries, knowledge of the morphology of T. callipaeda is scanty. Eighty-three nematodes collected from the eyes of naturally infected dogs from the Basilicata region (southern Italy) were examined by light and scanning electron microscopy, and the most important features of the nematodes were described. The morphological characteristics useful for the identification of T. callipaeda are discussed.

Two human cases of Thelazia callipaeda infection in Korea.

Thelazia callipaeda were observed from a 7-month old baby who lived in Uijongbu in 1989 and from a 42-year old man who lived in Anyang in 1994. These are the 23rd and 24th records of human thelaziasis in Korea as the literature are concerned.

Development of the nematode eyeworm, Thelazia skrjabini (Nematoda: Thelazioidea), in experimentally infected face flies, Musca autumnalis (Diptera: Muscidae).

The development of Thelazia skrjabini Erschow, 1928, was studied in experimentally infected laboratory-reared Musca autumnalis De Geer. Thelazia skrjabini developed to the infective third stage in a minimum of 9 days in M. autumnalis maintained at 27 +/- 2 C. First-stage larvae were not observed postinoculation, but second-stage larvae were first observed 3 days postinoculation. Development was asynchronous. Second- and third-stage larvae occur in capsules, occasionally in the head but primarily in the abdomen attached to fat bodies. First-stage larvae have anteriorly 1 ventral and 2 dorsal hooks, directed posteriorly. Second-stage larvae have 4 submedian cephalic papillae and faint annular striations. Third-stage larvae have 6 labial papillae, 4 submedian cephalic papillae and pronounced annulations. Morphometric studies of each larval stage were performed with specimens in glycerine.

Scanning electron microscopic observations of Thelazia callipaeda from human.

Four females and a male nematode isolated from 2 patients who visited eye clinics in Seoul were identified as Thelazia callipaeda and their ultrastructures were observed by scanning electron microscopy (SEM). General features of the worms were slender and attenuated at both ends. Vaginal opening was located at 0.27 mm from the anterior end, and in front of the esophago-intestinal junction. In the body cuticle transverse striations varied characteristically through the body. The number of cuticular transverse striations was 400-650/mm at head portion, 250/mm at middle portion and 300-350/mm at tail portion. The SEM observation of the mouth part of the females showed 6 cord-like cuticular thickenings in hexagonal arrangement and an amphid was observed. A lateral line, a vaginal opening, a pair of phasmids, and an anus were identified in the body portion. A pair of papillae and 6 cord-like cuticular thickenings were on the mouth part of the male. It was difficult to observe structures at the tail of the male except wrinkle-like structures. Most of the larvae isolated from the uterus of a female worm were sheathed and thus cuticular striations were not seen. Others were un-sheathed and revealed cuticular striations. The oval membrane which encysted sheathed larvae was also observed. These are the 18th and 19th record of human thelaziasis in Korea as the literature are concerned.

Presence of Thelazia callipaeda Railliet & Henry, 1910, in Piedmont, Italy.

A sample of 314 dogs from a zone of 80,000 ha in Piedmont, Italy, were examined for the presence of thelaziae under the nictitating membrane. Sixteen animals from eight districts were infected, the foothills being the main location of the parasitosis. All 44 nematodes collected were identified as Thelazia callipaeda.