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At least 19 recordsLinked to original sources
PubMed2000

Comparison of the Galleria baiting technique and a direct extraction method for recovering Steinernema (Nematoda: Rhabditida) infective-stage juveniles from soil.

Forty soil samples from forests and other biotopes in Germany and the Czech Republic were studied for the presence of entomopathogenic nematodes using the Galleria bait method at the same time as a sieving-decanting method for direct extraction of infective-stage juveniles. Five Steinernema species were recovered from the samples from Germany and four species from the samples from Czechia. All five species were recovered with both methods, but the baiting technique was generally less effective and mixtures of species were frequently undetected. The direct extraction method provided quantitative estimates of infective-stage juvenile density but no information on their infectivity or on morphological characters of adults, and nematode cultures could not be established.

Animals↗
PubMed2003

Impact of the host cadaver on survival and infectivity of entomopathogenic nematodes (Rhabditida: Steinernematidae and Heterorhabditidae) under desiccating conditions.

Entomopathogenic nematode species of Steinernema carpocapsae, Steinernema riobrave, or Heterorhabditis bacteriophora were used to compare survival and infectivity among infective juveniles (IJs) emerging in water from hosts in White traps (treatment a), emerging in sand from hosts placed in sand (treatment c), and emerging from hosts placed on a mesh suspended over sand (treatment m). Nematode survival and infectivity was recorded in sand at three-day intervals during 21 days of storage in desiccators at 75% relative humidity and 25 degrees C. Infectivity was measured by exposing 5 Galleria mellonella for 16 h to IJs. Treatment did not affect percent survival of H. bacteriophora IJs. Percent survival of S. riobrave and S. carpocapsae IJs was lowest in treatment a. Across all treatments, by 10 days after the beginning of the experiments, IJ survival declined to 93, 43, and 28% of levels on day 1 for H. bacteriophora, S. riobrave, and S. carpocapsae, respectively. For the three treatments, infection rate over time was described by a negative exponential function for S. riobrave and S. carpocapsae and by a sigmoid function for H. bacteriophora.

Animals↗
PubMed2003

Molecular phylogenetics and diagnosis of soil and clinical isolates of Halicephalobus gingivalis (Nematoda: Cephalobina: Panagrolaimoidea), an opportunistic pathogen of horses.

Phylogenetic relationships among six isolates of Halicephalobus gingivalis (Stefanski, 1954), a species with pathogenic potential in horses and humans, were evaluated using DNA sequences from the nuclear large-subunit ribosomal RNA (LSU rDNA) gene. Sequences from nematodes obtained from in vitro cultures (soil or clinical sources), or isolated from infected horse tissues, were compared. Gene sequences from a fatal equine clinical case from southern California and a free-living isolate recovered from southern California soil showed no fixed differences. Sequences from isolates representing two fatal equine cases from North America, one from Ontario, Canada and another from Tennessee also showed no fixed differences. In contrast, two equine cases from Tennessee had 18 fixed differences for this LSU region, the greatest observed among isolates from horses. Phylogenetic analysis of six Halicephalobus sequences and four outgroup taxa by maximum parsimony yielded one tree with five well-supported clades. This phylogeny did not group isolates of Halicephalobus strictly by region of geographic isolation or source of sample, and depicted one clinical and one soil isolate as sister taxa. These results confirm that free-living environmental isolates are potential sources of infection for horses. The phylogeny also reveals that diverse isolates can cause infections in horses within a relatively limited geographic region, and conversely that genetically similar sister taxa can be recovered from geographically distant localities. PCR primers that selectively amplify Halicephalobus DNA were designed and tested based on comparison of closely related nematodes as inferred from phylogenetic analysis.

Animals↗
PubMed1995

Ocular Halicephalobus (syn. Micronema) deletrix in a horse.

Ocular contents from a horse with a 4-week history of severe unilateral uveitis were submitted for histopathologic examination. A severe unilateral granulomatous chorioretinitis with intralesional Halicephalobus deletrix was diagnosed. The horse developed progressive neurologic signs several days following the surgery to remove ocular contents and implant a prosthesis and was subsequently euthanatized. A severe multifocal granulomatous encephalitis with intralesional H. deletrix, localized primarily to the optic chiasm, thalamus, and brain stem, was diagnosed from tissues acquired at necropsy. The other eye was not affected. This is the first report of ocular parasitism by H. deletrix and suggests possible systemic dissemination from a primary site in the eye.

Animals↗
PubMed2000

Halicephalobus gingivalis (Nematoda) infection in a Grevy's zebra (Equus grevyi).

A 6-yr-old female Grevy's zebra (Equus grevyi) with a disseminated rhabditiform nematode infection is described. Antemortem clinical signs were limited to blindness and abnormal behavior believed to be caused by a recurrent nematode-induced uveitis. Histologic examination of the kidneys, heart, eyes, uterus, and lymph nodes revealed granulomas containing multiple sections of rhabditiform nematodes. Most of the recovered nematodes were larval stages with only a few adult females noted. The adults measured 243-297 microm x 11-16 microm (x = 269 x 14 microm). The distinctive rhabditiform esophagi had corpus:isthmus:bulb proportions of 19:11:5. On the basis of adult morphology, the nematode was identified as Halicephalobus gingivalis. This is the first report of this parasite in a zebra and indicates that this parasitic granulomatous disease should be considered in zebras with neurologic disease.

Animals↗
PubMed2006

[Halicephalobus gingivalis infection in a 5-year-old Tinker gelding].

A 5-year old Tinker gelding was referred to the Department of Equine Sciences with a left eye uveitis and fever. At presentation the horse showed a mild lethargy, fever and decreased vision of the left eye. Rectal examination revealed an enlarged left kidney, with a hard and an irregular surface. The cranial mesentery artery had an enlarged and irregular aspect. Blood analysis showed anaemia, leucocytosis, increased blood urea nitrogen and creatinine and a hyperproteinemia. Urine analysis repeatedly showed a marked proteinuria and an increased gammaGT/creatinine ratio. The amount of abdominal fluid was slightly increased. However, the aspect, amount of cells and protein were normal. In the following two days the fever persisted and the horse showed anorexia and severe neurological signs. The horse was euthanized with permission of the owner. Post mortem examination showed a generalized parasitic infestation of Halicephalobus gingivalis in the uvea of the left eye, the kidneys and the central nerve system.

Animals↗
PubMed2001

Infection behavior of the rhabditid nematode Phasmarhabditis hermaphrodita to the grey garden slug Deroceras reticulatum.

Infection behavior of the rhabditid nematode Phasmarhabditis hermaphrodita to the grey garden slug Deroceras reticulatum was studied. The dauer (enduring or nonaging) juveniles of P. hermaphrodita invade D. reticulatum within 8-16 hr following external exposure, with the posterior mantle region containing the shell cavity serving as the main portal of entry. The dauer juveniles can recover, multiply, and produce new dauer juveniles in the slug and slug feces homogenates, but not in the soil extract. These results demonstrate that P. hermaphrodita is a facultative parasite of the slug and can complete its life cycle under nonparasitic conditions associated with the host. Although the juvenile and adult nematodes can kill the slug if injected into the shell cavity of the host, only the dauer juvenile can serve as an infective stage in the natural environment.

Age Factors↗
PubMed2005

Diploscapter coronata infection in Thailand: report of the first case.

A 73-year-old Thai woman living in Mueang District, Saraburi Province, central Thailand presented with numerous hookworm-like nematodes, finally revealed as Diploscapter coronata, by fecal culture. The patient exhibited no significant clinical signs of the gastrointestinal or genitourinary systems, and was generally not ill as a result of this unusual infection. Less commonly, patients have presented with symptoms and signs of Diploscapter coronata infection. However, potentially serious consequences can occur where people have exposure to an environment that has been contaminated with infected feces, or more specifically, infective eggs; such conditions could lead to human infection with Diploscapter coronata worms. This was the first reported occurrence of human Diploscapter coronata infection in Thailand.

Aged↗
PubMed2004

Morphological and biological study of Rhabdias spp. (Nematoda) from African chameleons with description of a new species.

Lung-dwelling females of Rhabdias (Rhabdiasidae), and possible migrating ceolomic young females were searched for in 46 chameleons, belonging to seven species. Rhabdias chamaeleonis, the single species identified to date in Africa, was found in Chamaeleo (Trioceros) johnstoni and C. (T.) hoehnelii, and redescribed; the sizes of the buccal capsule and oesophagus were stable compared to the length of the female parasiles, which varied from 6 mm to 22 mm in length. A second species, R. jarki n. sp., was identified from one C. (T.) johnstoni; it differed from R. chamaeleonis in the shape of anterior region, the longer and slender oesophagus (ratio bulb diameter-body diameter at that level about 1/5 instead of 1/2), the arrangement of the head papillae, the shape of the buccal capsule, and the anatomy of the genital apparatus: one of the ovaries (the anterior or posterior one according to the specimen) had a band of small cells, among larger ovocytes of the synapsis zone, which were likely to generate the spermatozoa present in the oviducts, whereas these two elements were absent from R. chamaeleonis. The parasitic females of R. jarki thus appeared to be hermaphroditic, whereas those of R. chamaeleonis appeared to be parthenogenetic. The free living phase of these Rhabdias species was heterogonic. The infective larva of R. chamaeleonis was 360-590 microns long, unmolile and at third stage inside the maternal cuticle. The free-living male of R. jarki was described. The numerous infective larvae recovered from cultures of unidentified Rhabdias were all in maternal cuticle (one larva/female instead of two as in R. gemellipara from Calumma parsonii, from Madagascar) and two kinds of larvae were identified, R. chamaeleonis and larvae 700-900 microns long provisionally identified to R. jarki. The behaviour of infective larvae and a few successful infections of insects suggest that, in the field, insect transport hosts are involved in transmission and in preventing infective larvae from drying out.

Animals↗
PubMed1998

Halicephalobus gingivalis (Stefanski, 1954) from a fatal infection in a horse in Ontario, Canada with comments on the validity of H. deletrix and a review of the genus.

Although the original description given by Stefanski (1954) was satisfactory, Anderson & Bemrick (1965), in describing H. deletrix (= Micronema deletrix), claimed Stefanski's description was "inadequate" and the species a "species inquirenda". Thus, infections in horses and humans have been assigned to H. deletrix. We believe the species reported in horses and humans is H. gingivalis and that H. deletrix is its synonym. H. gingivalis is separated herein from forms found free-living. The genital tract in the advanced fourth stage of H. gingivalis is didelphic and amphidelphic and terminal ends of the horns are reflected, the anterior one ventrally, the posterior one dorsally. In the adult parthenogen the latter forms a short ovary, whereas most of the anterior horn forms a combined uterus-oviduct as a receptacle for a single large egg which is laid in the 2-cell or multi-cell stage. Eggs in the 2-cell stage embryonated to larvae in 17 hours at 28 degrees C but did not hatch until an additional 24 hours. First-stage larvae were unusually large and variable in length (136-199 microns x = 168). Inactive third-stage larvae were 180-240 microns (x = 203) in length. The possible route of infection in horses and humans is briefly discussed.

Animals↗
PubMed1995

The susceptibility of different species of sciarid flies to entomopathogenic nematodes.

Steinernema feltiae is the most effective nematode for controlling sciarid species but S. carpocapsae does exert some control. S. feltiae is less effective at 30 degrees C than at 22 degrees C. S. anomali, S. riobravis and two Heterorhabditis spp. gave better control at the higher temperature. All six sciarid species tested were susceptible to S. feltiae but there was some variation in the level of infection. UK isolates of S. feltiae were more effective against UK sciarids than the nematode isolates from other European countries which were tested. Adult sciarids are infected by S. feltiae and can disperse nematodes to nematode-free compost.

Animals↗
PubMed2004

Human infection with Photorhabdus asymbiotica: an emerging bacterial pathogen.

The three currently recognised Photorhabdus species are bioluminescent bacteria that are pathogenic to insects. P. luminescens and P. temperata form a symbiotic relationship with nematodes that infect insects. P. asymbiotica, on the other hand, has only been isolated from human clinical specimens from the USA and Australia. The bacterium has been associated with locally invasive soft tissue and disseminated bacteraemic infections. An invertebrate vector for P. asymbiotica has not yet been identified.

Communicable Diseases, Emerging↗
PubMed1995

The effect of temperature on infection, development and reproduction of heterorhabditids.

The effect of temperature on infection, development and reproduction of five Heterorhabditis isolates was examined in Galleria mellonella larvae. Infectivity was examined at six temperatures (5, 10, 15, 20, 25 and 30 degrees C). The proportion of Galleria infected remained relatively constant, only dropping at extremes of the temperature range tested. However, the mean number of nematodes per host produced a different trend, with each isolate displaying optimal infectivity at 25 degrees C. The temperature range over which the juveniles could infect differed between the isolates. This is thought to be related to the geographic origins of the species. Development and reproduction occurred over a slightly narrower temperature range than that allowing infection to occur. Differences between the isolates at which development and reproduction occurred were noted. There were also differences in the mean number of juveniles produced per cadaver following either infection in sand (10 nematodes/larva) or the injection of one juvenile per larva, suggesting that reproduction is tightly regulated by density-dependent constraints.

Animals↗