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At least 19 recordsLinked to original sources
PubMed2005

Analysis of genetic variability within Thelazia callipaeda (Nematoda: Thelazioidea) from Europe and Asia by sequencing and mutation scanning of the mitochondrial cytochrome c oxidase subunit 1 gene.

This study investigated genetic variability within the 'eyeworm'Thelazia callipaeda (Nematoda: Thelazioidea) from Europe and Asia by polymerase chain reaction (PCR)-coupled sequencing and mutation scanning of the mitochondrial cytochrome c oxidase subunit 1 gene (cox 1). Eight different sequence variants of cox 1 (haplotypes) were determined for the 50 individual adult specimens of T. callipaeda (from dogs, foxes or cats from Italy, Germany and the Netherlands and from dogs from China and Korea). Nucleotide variation (0.3--2%) was detected at 23 of 649 positions in the cox 1. Six of these positions were invariable among all 37 individuals from Europe and among the 13 individuals from Asia (irrespective of host origin) but differed (five G<-->A and one C<-->T changes) between Europe and Asia. PCR-based single-strand conformation polymorphism (SSCP) analysis of the most variable portion (v-cox 1) of the cox 1 was validated (for a subset of samples) as a tool to rapidly screen for genetic (haplotypic) variability. The results for the SSCP analysis and sequencing were concordant, indicating that the mutation scanning approach provides a useful tool for investigating the population genetics and molecular ecology of T. callipaeda.

Animals↗
PubMedDate not supplied

Helminths of birds and mammals of Israel. VII. - Pneumospirura rodentium n. sp. (Pneumospiruridae - Thelazioidea).

Pneumospirura rodentium a lung parasite of Gerbillus dasyurus and Meriones crassus is described. P. hainanensis Wu and Hu, 1938 and Metathelazia servalis Chabaud and Biocca, 1950, have cephalic structures resembling those of P. rodentium. But the three species can be differentiated by the size of spicules, their localization, hosts and geographical distribution.

Animals↗
PubMedDate not supplied

Scanning electron microscopy of the cephalic structures of Pneumospiruridae. (Thelazioidea - Nematoda). Revision of the family.

In a study with the scanning electron microscope (SEM) five different types of cephalic structure were found in five species of Pneumospiruridae recorded in Israel. The description, in the literature, of a sixth type, based on a study with the light microscope, was also considered in evaluating the results. By comparing descriptions and drawings of the known Pneumospiruridae with the SEM micrographs the species in the family were grouped into two genera: 1. Vogeloides Dougherty, 1952 in which the form of the cephalic structures could be correlated with the structure of the oesophagus; 2. Metathelazia Skinker, 1931 in which the cephalic structures could not be correlated with any other morphological or anatomical character. The species included in the genus Metathelazia were therefore grouped on the basis of the form of cephalic structures in 5 types: booliati, multipapillata, acomysi, capsulata and rodentium. The genus Pneumospirura Wu and Hu, 1938 is considered a subjective synonym of Metathelazia.

Animals↗
PubMed2004

Molecular characterization of the first internal transcribed spacer of ribosomal DNA of the most common species of eyeworms (Thelazioidea: Thelazia).

Spirurid nematodes of the genus Thelazia cause ocular infection in several mammals and are transmitted by dipteran flies. Of the 10 described species, T. gulosa, T. rhodesi, T. skrjabini (affecting cattle), T. lacrymalis (affecting horses), and T. callipaeda (affecting carnivores and humans) are the most common. The aim of this study was to characterize the first internal transcribed spacer (ITS1) ribosomal DNA sequences of these 5 species. The length of the ITS1 sequences ranged from 357 bp (T. lacrymalis) to 905 bp (T. callipaeda). Interspecific differences ranged from 35 to 77%. Polymorphic sites were detected in each species. Intraspecific variation varied from 0.3 to 2.5%. The characteristics of the ITS1 of Thelazia spp. show similarities to those of other Spirurida. The findings of this present study show that the ITS1 represent a powerful genetic marker for the molecular identification of eyeworms and a useful tool for developing molecular epidemiological techniques to study Thelazia spp. transmission patterns and prevalence in definitive and intermediate hosts.

Animals↗
PubMed1993

First report of immature Thelazia skrjabini (Nematoda: Thelazioidea) from the eye of a white-tailed deer, Odocoileus virginianus.

The eyes from 103 hunter-killed white-tailed deer (Odocoileus virginianus), and 19 mule deer (O. hemionus) killed between 28 November to 14 December 1991 from Wainwright, Alberta were examined for Thelazia spp. One immature male and two immature female Thelazia skrjabini were collected from beneath the third eyelid of one adult female O. virginianus. This is the first report of T. skrjabini in a member of the Cervidae.

Animals↗
PubMed1991

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.

Animals↗
PubMed1990

A study on the prevalence and intensity of occurrence of Thelazia skrjabini (Nematoda: Thelazioidea) in cattle in central Alberta, Canada.

The distribution of Thelazia skrjabini in the eyes of cattle was examined from necropsies on 297 animals. Although the overall prevalence in beef cattle (21.5%) was similar to that in dairy cattle (25.7%), in general worms were more abundant in beef than in dairy animals. The worm prevalence was lowest in the months from March to June and highest in September among beef and dairy animals. Thelazia skrjabini was found in 76 (16.8%) eyes from beef, and 23 (16.4%) eyes from dairy cattle. Infections were not randomly distributed among the eyes of cattle. Significantly more dairy and beef cattle contained T. skrjabini in both eyes than expected based on the observed prevalences. Based on chi-square probabilities, significantly more cattle more than 2 yr of age and less than 10 mo of age were infected with T. skrjabini. Although all age groups were infected, more worms were observed in cattle more than 2 yr of age. More female worms than males were collected from cattle. The male-to-female ratio of 1:2 was consistent regardless of cattle age, season, or type.

Age Factors↗
PubMed1989

Prevalence and intensity of Thelazia spp. (Nematoda: Thelazioidea) in a Musca autumnalis (Diptera: Muscidae) population from Central Alberta.

A face fly (Musca autumnalis) population near Wetaskiwin, central Alberta, Canada, was sampled 9 times from 26 July to 29 September 1988 for the early larval stages of Thelazia spp. Of 426 female flies examined, 159 (37%) contained Thelazia spp. (almost exclusively T. skrjabini), with an average worm burden of 4.2 larvae per infected fly. Prevalence ranged from 17 to 56% over 9 collections. This is the first report of Thelazia skrjabini in flies from western North America and the highest Thelazia prevalence in face flies yet reported in North America. The face fly population was also parasitized by Heterotylenchus autumnalis, with a prevalence of 5.5%.

Alberta↗
PubMed1994

Site segregation of Thelazia skrjabini and Thelazia gulosa (Nematoda: Thelazioidea) in the eyes of cattle.

One thousand three hundred and twenty-two eyes obtained from slaughtered cattle throughout Alberta were examined for eyeworms. Each eye was partitioned into 9 sites and all eyeworms were recorded by site. Seven hundred eyeworms were recovered from 121 infected eyes. The distribution of Thelazia skrjabini across the 9 sites differed significantly (P < 0.001) from that of Thelazia gulosa. The 2 major lacrimal ducts associated with the Harderian gland contained 58% (354/613) of the T. skrjabini present, whereas the large ventral lateral duct of the orbital gland contained 58% (50/87) of the T. gulosa recovered. Eyeworms occurred more often (90%, 631/700) in a duct as a single species than as a mixed species infection (10%, 69/700). The data suggest that T. skrjabini and T. gulosa are more site specific than previously believed.

Animals↗
PubMed1994

The effect of treating beef cattle on pasture with ivermectin on the prevalence and intensity of Thelazia spp. (Nematoda: Thelazioidea) in the vector, Musca autumnalis (Diptera: Muscidae).

Trihedron sticky traps were used to monitor the prevalence and intensity of Thelazia spp. in face flies associated with 2 groups of cattle. Traps were set for 24 hr once a week beginning 2 wk before cattle were turned out to pasture following winter housing and continued until flies reached diapause in October. The 50 heifers in group 1 received 1 treatment with ivermectin (Ivomec Pour-On for cattle, 500 micrograms/kg body weight) on the day of turnout onto pasture. The 50 cows and their calves in group 2 were not treated. Treating cattle with ivermectin delayed the onset of infection in Musca autumnalis by 20 days and reduced the prevalence to 2.2% compared to 26.9% in flies from the control pasture. Although residues of ivermectin eradicate many fly larvae developing in cattle feces, there was no significant difference in the number of flies counted on the faces of cattle or in the number of flies caught on sticky traps on the 2 pastures (P > 0.05).

Alberta↗
PubMed1993

Prevalence of eyeworms (Nematoda: Thelazioidea) in beef cattle grazing different range pasture zones in Alberta, Canada.

The eyes from 410 beef cattle grazing 6 range pasture zones in Alberta were dissected and examined for species of Thelazia. Thirty-eight (9.3%) contained eyeworms: 25 (6.1%) contained Thelazia skrjabini alone, 3 (0.7%) contained Thelazia gulosa alone, and 10 (2.4%) had a mixed infection of T. skrjabini and T. gulosa. Prevalence was related to the type of pasture. The prevalence was lower in cattle grazing short- and mid-grass pastures (zones 1, 2; 0% and 1.5%, respectively) than those grazing transitional or aspen parkland pastures (zones 3, 5; 7.4% and 6.2%, respectively) or rough fescue or woodland type pastures (zones 4, 6; 11.3% and 18.4%, respectively). The data suggest that prevalence is related to pasture type that limits the number of its vector, Musca autumnalis.

Alberta↗
PubMed1994

The evolutionary expansion of the Spirurida.

The possible origins of the 12 superfamilies of the Spirurida are considered, based on comparative morphology, host and geographic distributions. The available evidence suggests a complex origin of these nematodes, some families being derived from the Seuratoidea, and others from the Cosmocercoidea (Ascaridida). The spirurid radiation is an old one and seems to have occurred primarily in the Secondary or early Tertiary eras. Since then, expansion has occurred with host capture as a prominent mechanism. The Dracunculoidea Procamallanidae and Camallanidae are probably derived from the Chitwoodchabaudiidae and the Rictularioidea from the Schneidernematidae. The Seuratidae may have given rise to the Gnathostomatoidea, the Physalopteroidea, the Thelazioidea, the Habronematoidea, the Spiruroidea and the Acuarioidea. The filarioid nematodes appear to have several origins with the Diplotriaenoidea derived from the Spiruroidea, while constituents of the Aproctoidea derived from the Cystidicolinae, the Seuratoidea and the Spiruroidea. The Filarioidea are thought to have arisen from the Spiruroidea and the Thelazioidea. The evolution of tissue parasitism as a secondary phenomenon is considered in various groups.

Adaptation, Biological↗
PubMed2003

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.

Animals↗
PubMed1975

Conjunctivitis due to Thelazia californiensis.

A patient with chronic conjunctivitis was found to have a parasitic nematode infection of the conjunctiva. The parasite was found within the cul-de-sac of the conjunctiva, entirely motile. The treatment of the conjunctivitis was simple removal of the organism, and periodic follow up.

Adult↗
PubMed1987

Early third-stage larvae of Gnathostoma hispidum in cyclops. Surface topography revealed by scanning electron microscopy.

Surface structures of the early third-stage larvae were examined by scanning electron microscopy. There were hemispherical head-bulbs at the apical ends. These bulbs could be clearly distinguished from the bodies. The head-bulbs (52 X 29 micron) had four transverse rows of sharp hooklets. The number of hooklets in each row was 37, 36, 38, and 43, posteriorly. The larvae posessed a pair of lateral lips in the head-bulb. Each of the lips had two labial papillae and an amphid between the papillae. Small unidentate cuticular spines were present along the entire length of larvae on their transverse striations. The number of these cuticular striations was 175-217. A pair of cervical papillae and an excretory pore were present on the anterior part of the body. Another pair of papillae was detected laterally on the posterior one-third of the body. The shape of the posterior body papillae resembled that of cervical papillae. The cuticular spines were absent around the anus.

Animals↗
PubMed1992

Studies on the developmental cycle of Trichospirura leptostoma (Nematoda: Thelaziidae). Experimental infection of the intermediate hosts Blatella germanica and Supella longipalpa and the definitive host Callithrix jacchus and development in the intermediate hosts.

The cockroaches Blatella germanica and Supella longipalpa can act as intermediate hosts of Trichospirura leptostoma as demonstrated by experimental infestation. The parasite developed from the embryonated egg into the infective larval stage (L3) in cockroaches within 5-6 weeks. After experimental infection of marmosets (Callithrix jacchus), eggs were first found in faecal samples (prepatency) at 8-9 weeks post-infection. Patency lasts about 2 years. Despite the presence of living adult worms in the marmosets' pancreas, no additional eggs were observed in their faeces after the patent period.

Animals↗