Hepatic pathology of experimental Parascaris equorum infection in worm-free foals.
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Animals↗
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Thienylvinylindoles as inhibitors of mitochondrial NADH dehydrogenase.
In connection with a previous study, new phenylindoles bearing a 2- or 3-thienyl group were synthesized and tested as specific inhibitors of mitochondrial NADH dehydrogenase. The position of the phenyl ring and the geometrical configuration play an important role in the activity and specificity of these derivatives. In order to study the mechanism of action of these thienylvinylindoles, their activity was compared with that of known inhibitors in a new test employing exogenous quinones.
Animals↗
The radioallergosorbent test (RAST) for the serological diagnosis of human anisakiasis.
The serum of patients with parasitologically confirmed and one patient with a clinically presumptive case of anisakiasis were tested by the radioallergosorbent test (RAST) and counter-electrophoresis (CEP) for IgE and IgG antibodies, respectively, using antigens prepared from larval (L3) stage Anisakis simplex and larval (L2) stage Toxocara canis. All sera were RAST-positive to the A. simplex antigen and RAST-negative to the T. canis antigen. All sera were CEP-negative to both antigens. The presence of a specific IgE antibody suggests that the RAST could serve as a useful technique for the serodiagnosis of anisakiasis in man.
Adult↗
Biochemical polymorphism in Parascaris equorum, Toxocara canis and Toxocara cati.
Vertical starch gel electrophoresis was used to resolve proteins encoded by 18 gene loci in ascaridoid nematodes. Estimates of genetic variability were made from population samples of the dog ascarid (Toxocara canis), cat ascarid (Toxocara cati), and the horse ascarid (Parascaris equorum). Levels of polymorphism and mean heterozygosity were high, which is not consistent with the hypothesis that the intestinal environment selects for monomorphism among endoparasites. Most observed allele frequencies conformed to Hardy-Weinberg equilibrium expectations as tested by chi2 goodness-of-fit, suggesting that the proteins evaluated are inherited in a Mendelian fashion and that these nematodes are mating at random. Subunit structures of the following enzymes, deduced from electrophoretic phenotypes of heterozygotes, corresponded to those of vertebrates: lactate dehydrogenase; malate dehydrogenase; 6-phosphogluconate dehydrogenase; phosphoglucomutase; esterase D; peptidase B; peptidase D; and mannose-6-phosphate isomerase. This observation substantiates the conservative nature of polypeptide subunit number across phylogenetically diverse groups of organisms.
Alcohol Oxidoreductases↗
Characterisation of surface antigens of Strongylus vulgaris of potential immunodiagnostic importance.
When antigens prepared by detergent washes of Strongylus vulgaris and Parascaris equorum were probed in an enzyme-linked immunosorbent assay test with horse sera from single species infections of S. vulgaris and P. equorum, a high degree of cross-reaction between the species was demonstrated. Western blot analysis of four common horse nematode species showed a large number of common antigens when probed with horse infection sera. Antisera raised in rabbits against the four species, including S. vulgaris, were also found to cross-react considerably. Rabbit anti-S. vulgaris sera were affinity adsorbed over a series of affinity chromatography columns, bound with cross-reactive surface antigens, to obtain S. vulgaris-specific antisera and thereby identify S. vulgaris-specific antigens by Western blotting. These studies revealed potentially specific antigens of apparent molecular weights of 100,000, 52,000, and 36,000. Of these bands, only the 52 kDa and 36 kDa appeared to be found on the surface as judged by 125I-labelling of intact worms by the Iodogen method, although neither protein was immunoprecipitated by horse infection sera. Finally, immunoprecipitation of in vitro translated proteins derived from larval S. vulgaris RNA suggests that two proteins may be parasite-derived. These findings are discussed both with respect to the surface of S. vulgaris and to the use of these species-specific antigens in immunodiagnosis.
Animals↗
Critical tests of morantel-trichlorfon paste formulation against internal parasites of the horse.
Critical tests were completed on six horses to evaluate the antiparasitic activity of a paste formulation mixture of morantel citrate and trichlorfon, administered intraorally at the dose rate of 6 mg morantel base kg-1 and trichlorfon at 30 mg kg-1. Aggregate average removals were: 78% for two horses infected with 2nd instar Gasterophilus intestinalis; 100% for one infected with 2nd instar G. nasalis; 96% for six infected with 3rd instar G. intestinalis; 100% for four infected with 3rd instar G. nasalis; 100% for five infected with Parascaris equorum; 100% for one infected with mature Oxyuris equi; 100% for five infected with Strongylus vulgaris; 72% for five infected with S. edentatus; and partial removal (25%) of Anoplocephala perfoliata infection from one infected animal. Pre- and post-treatment EPG and LPG data indicated a reduction of 97% of the mature small strongyle infections. Evidence of toxicosis was not observed in any of the horses.
Animals↗
Pathogenesis of helminths in equines.
This review summarizes information on the clinical signs, gross and microscopic lesions associated with nematode and cestode infections and discusses the development of these conditions in the equine host.
Animals↗
Effect of parbendazole and piperazine adipate on the activity of some enzymes of Ascaridia galli and Heterakis gallinae.
Adult Ascaridia galli and Heterakis gallinae obtained from the fowl (Gallus gallus) were treated in vitro with 10(-2) to 10(-5) M parbendazole and piperazine adipate for 10-60 min at 38 degrees C. Both the compounds at 10(-2) M caused mortality of A. galli and H. gallinae after a maximum of 30 min exposure. The effect of the drugs on the homogenates of the treated worm was investigated. Parbendazole (10(-2) M) inhibited malate oxidation by 68% in A. galli and 62% in H. gallinae. Piperazine adipate (10(-2) M) inhibited malate oxidation by 78% in both parasites. In A. galli oxaloacetate reduction was inhibited by 41 and 26% by 10(-2) M parbendazole and piperazine adipate, respectively; with H. gallinae this inhibition was found to be 39 and 55%, respectively. Aldolase activity in both the parasites was also inhibited by 10(-2) M parbendazole and piperazine adipate. Both compounds caused an inhibition of acid phosphomonoesterase activity, but the activities of lactate dehydrogenase and alkaline phosphomonoesterase were not affected significantly. Parbendazole (10(-2) M) had no significant effect on the cholinesterase activity of these parasites, but piperazine adipate (10(-2) M) caused an inhibition of 96% in A. galli and 93% in H. gallinae. The possible mode of action of the drugs is discussed.
Acid Phosphatase↗
The effect of levamisole and albendazole on some enzymes of Ascaridia galli and Heterakis gallinae.
Ascaridia galli and Heterakis gallinae obtained from the common fowl Gallus gallus were exposed to 10(-2)-10(-5)M levamisole and albendazole; both compounds caused death of the parasites in vitro. The effect of the drugs was investigated on homogenates of the treated worms. Albendazole, at 10(-2)M, inhibited oxaloacetate reduction by 67 and 53% and malate oxidation by 21 and 17% in A. galli and H. gallinae, respectively, whereas 10(-4)M levamisole completely inhibited malate dehydrogenase activity in both directions in the two parasites. Lactate dehydrogenase was not affected significantly by either anthelmintic. Aldolase activity was diminished by 57 and 32% in A. galli and H. gallinae, respectively, with 10(-4)M levamisole. Levamisole at 10(-4)M also inhibited the activity of acid and alkaline phosphomonoesterase and cholinesterase. Albendazole had no significant effect on these enzymes in either parasite. Malate dehydrogenase and cholinesterase activity of the host tissue (intestine and caecum) was also reduced significantly with 10(-2) and 10(-3)M levamisole. These studies indicated a multiple mode of action of levamisole and albendazole.
Albendazole↗
Dose titration of moxidectin oral gel against migrating Strongylus vulgaris and Parascaris equorum larvae in pony foals.
Moxidectin was tested for efficacy in ponies against experimental infections of 56 day Strongylus vulgaris larvae and 11 day Parascaris equorum larvae. Three dosages of moxidectin were tested: 300 micrograms per kg live body weight, 400 micrograms per kg, and 500 micrograms per kg, and the vehicle served as control. Ponies were first infected with 600 S. vulgaris third-stage larvae (L3) on Experiment Day 0 and then with 3000 embryonated P. equorum eggs on Day 45. Moxidectin treatments were administered on Day 56 and necropsy examinations were performed on Day 91. Strongylus vulgaris fourth-stage (L4) and fifth-stage (L5) larvae were recovered at necropsy from the control ponies, in dissections of the cranial mesenteric artery and its branches (L4 and L5), and recovered from nodules in the wall of the cecum and ventral colon (L5). Parascaris equorum larvae were recovered from the small intestine of control ponies. Moxidectin was highly efficacious against S. vulgaris L4 and L5 at all three doses tested (99.6-100%), and appeared to be equally efficacious against P. equorum larvae (100%); however, control ponies had low levels of P. equorum infections compared to previous experimental infections performed using identical methods. This suggests that the prior S. vulgaris infection on Day 0 may have influenced the subsequent experimental P. equorum infection on Day 45 and contributed to the lower recovery.
Administration, Topical↗
Severe and fatal central nervous system disease in humans caused by Baylisascaris procyonis, the common roundworm of raccoons: a review of current literature.
Baylisascaris procyonis, a parasitic infection of raccoons, causes severe neurologic disease in humans when infective eggs from raccoon feces are ingested. Definitive diagnosis is challenging, but can be made by isolation of larvae in brain biopsy or exclusion of other potential causes of eosinophilic meningoencephalitis. Prevention efforts are critical due to the lack of effective treatment.
Animals↗
Lagochilascaris minor third-stage larvae secrete metalloproteases with specificity for fibrinogen and native collagen.
Dissemination of parasitic infections depends on migration through tissues and evasion from both hemostatic processes and immune responses from hosts. Metalloproteases play major roles in these mechanisms of pathogen-host interactions and, thus, are considered drug targets. In this study, we characterized metalloprotease activities in excretory/secretory (ES) products from third stage larvae (L3) of the ascarid Lagochilascaris minor, the causative agent of lagochilascariosis, which demonstrates an impressive migrating capacity across host tissues, including bone. Gel enzymography showed that ES products of L3 display two major gelatinolytic activities. Optimal proteolytic activity was found to occur at neutral/alkaline pH and was associated with two L. minor-secreted metalloproteases of 59 (SM59(Lm)) and 114kDa (SM114(Lm)). We next showed that ES products of L3 were able to hydrolyze fibrinogen and collagen I at neutral pH, but not BSA, in an extensive manner. Furthermore, we demonstrated that ES products of L3 mediate hydrolysis of the triple helical structure of collagen I fibers in mouse mesentery. These results suggest that ES proteases of L3 might facilitate both L. minor migration through host tissues by hydrolyzing collagens of the extracellular matrix and evasion from host hemostatic mechanisms by degrading fibrinogen.
Animals↗
Chromatin diminution leads to rapid evolutionary changes in the organization of the germ line genomes of the parasitic nematodes A. suum and P. univalens.
Chromatin diminution in the parasitic nematodes Ascaris suum and Parascaris univalens represents a rather complex molecular phenomenon that includes chromosomal breakage, DNA degradation and new telomere formation. At a given elimination site, DNA breakage and new telomere addition does not take place at a single chromosomal locus but at many different places within a several kilobase long chromosomal region, referred to as chromosomal breakage region (CBR). Here we describe the cloning and the characterisation of seven CBRs from A. suum and P. univalens and we show that the process has been conserved between the two species. A detailed sequence comparison provides evidence that the sequences of the CBRs and their flanking regions are not directly important for the specification of the elimination sites. Six out of the seven CBRs are conserved between the two nematode species, suggesting that they have already existed in a common ancestor. We present a hypothesis stating that the elimination process ensures the maintenance of a functional somatic genome and concomitantly allows extremely rapid and profound changes in the germ line genome, thereby allowing the development of new germ line specific functions and thus providing a selective advantage for the chromatin eliminating nematodes during further evolution.
Animals↗
Anisakid parasites of two forkbeards (Phycis blennoides and Phycis phycis) from the Mediterranean coasts of Andalucía (Southern Spain).
An epidemiological survey of anisakids was carried out on 209 specimens of greater forkbeard (Phycis blennoides) and 58 of forkbeard (Phycis phycis) captured off the Mediterranean coasts of Andalucía (southern Spain). Four species of nematodes were identified: Anisakis simplex s.l., Anisakis physeteris, Hysterothylacium aduncum and Hysterothylacium fabri. The total prevalence was 62.06% in the forkbeard and 58.85% in the greater forkbeard. The highest values of prevalence (56.90%), mean intensity (5.21) and mean abundance (2.96) were all obtained for H. fabri in the forkbeard. The most frequent parasite in the greater forkbeard was H. aduncum with 51.20% prevalence and values of 3.00 and 1.53 for mean intensity and mean abundance, respectively. The infestation parameters were also analyzed according to the host length, observing a maximum of parasitized fish (91.67%) in samples of P. blennoides longer than 40 cm, while in P. phycis, the highest prevalence (82.35%), conditioned by H. fabri parasitization, was found in fish with lengths between 30 and 35 cm.
Animals↗
Treatment of Baylisascaris procyonis infections in dogs with milbemycin oxime.
An examination was made as to the ability of Sentinel Flavor Tabs (milbemycin oxime/lufenuron) to treat Baylisascaris procyonis infections in dogs. The study was designed as a critical trial and included five naturally infected dogs and two dogs that were experimentally infected. Another dog from a prior clinical trial that was treated with Sentinel Flavor Tabs as part of the original FDA submission package for intestinal nematode infections was also included with the treated dogs. Of the five naturally infected dogs treated as part of the critical trial, three were cleared of their infections. These five dogs passed a total of 52 worms after treatment; one dog retained 23 worms and the other retained 1 worm at necropsy 7 days after treatment. Two of five experimentally infected Beagle dogs that had been given mice that had been fed 200 infectious eggs, developed patent infections with the parasite. These dogs were treated, and one of the dogs passed one worm and the other passed two worms after treatment with no worms being detected at necropsy 7 days after treatment. The one dog that was treated with milbemycin oxime as part of the FDA submission was clear of worms at necropsy. Overall, the mean efficacy of Sentinel Flavor Tabs was found to be 91.0%. Of the eight dogs that were treated, six were totally cleared of their infections, a cure rate of 75%. The two dogs that did not clear their infections had very large numbers of adult B. procyonis within their intestinal tracts at the time of treatment, one dog had 40 worms (23 remaining) and the other had 26 worms (1 remaining). It is suggested that the treatment of dogs with monthly Sentinel Flavor Tabs could markedly reduce the chance of infected dogs contaminating the environment. Also, additional monthly treatments are highly likely to clear dogs of any worms not killed with the initial treatment.
Animals↗
Contracaecum sp. infection in Hoplias malabaricus (moncholo) from rivers and marshes of Colombia.
Nematode infection indices were recorded in Hoplias malabaricus captured in six different rivers and a marsh belonging to the North Coast Basin of Colombia, and from the Amazon River, during February 2003-December 2004. Preliminary morphological analysis of nematodes indicated the presence of Contracaecum sp. Parasites were mostly found in the intestinal mesenteries and a very low percentage in muscle. Parasite prevalence in all sampling locations at the north of Colombia was 100%, whereas in the Amazon River it was 6.12%. The mean intensity in the different stations were as follows: Magdalena River at the City of Magangué (58.92+/-7.59), Magdalena river at the city of Zambrano (128.9+/-7.08), Sinú River (53.88+/-4.92), Dique Channel (207.3+/-59.52), Cauca River (77.26+/-9.35), Atrato River (21.11+/-2.6), San Jorge River (39.5+/-7.13), and Totumo Marsh (62.5+/-6.38). In average, all specimens of Hoplias malabaricus from the north coast basin of Colombia were infected with a mean intensity of 77.82+/-4.81 (1-466 parasites per host) whereas in fish from the Amazon River this value was significantly lower (intensity 1.0+/-0.0). Size and weight correlated significantly with parasite intensity in fish collected from sampling locations at the north of Colombia (R=0.240, P<0.001 and R=0.199, P=0.008, respectively). Moreover, a significant, but low and negative correlation was found between condition factor and parasite intensity (R=-0.159, P=0.034), suggesting a possible impact of parasites on fish health. These results suggest, for the first time, that the parasitism in Moncholo is a widespread phenomenon in Colombian rivers and could represent a risk factor for human consumers.
Animals↗
Effects of low and high temperatures on viability of Parascaris equorum eggs suspended in water.
Microcentrifuge tubes containing 5000 eggs of Parascaris equorum suspended in water were frozen at -5, -10, -15, -20, and -80 degrees C for 1-168 h and then thawed at a room temperature. Other samples of P. equorum eggs suspended in water were inserted into wells in the heated metal block of a thermal DNA cycler. Block temperatures were set at 5 degrees C incremental temperatures from 40 to 100 degrees C. At each temperature setting microcentrifuge tubes containing P. equorum eggs were removed 1 and 5 min later. Both, frozen and heated egg suspensions as well as untreated control suspensions were then incubated to test of viability based on the development of infective larvae inside viable eggs. We found out that eggs of P. equorum in water can retain viability and infectivity after freezing and that eggs survive longer at higher freezing temperatures. Our results also indicated that when water containing P. equorum eggs reached temperatures of 60 degrees C or higher within 1 min, the viability of eggs was lost.
Animals↗
Macrocyclic lactone-resistant Parascaris equorum on stud farms in Canada and effectiveness of fenbendazole and pyrantel pamoate.
The aims of studies in 2002 and 2003 on three farms with 76 foals naturally infected with Parascaris equorum were to (i) identify if the nematode was resistant to ivermectin and moxidectin, and (ii) confirm the effectiveness of fenbendazole and pyrantel pamoate for the parasite. Twelve clinical trials, each with a Fecal Egg Count Reduction Test, were conducted on two Thoroughbred and one Standardbred farms in southwestern Ontario, Canada. In each trial, Parascaris eggs/g feces were estimated for each foal pre- and post-treatment using the Cornell-Wisconsin double flotation and Cornell-McMaster dilution techniques. On each farm and for each trial, foals were randomized into treatment groups. Treatments were ivermectin, moxidectin, fenbendazole, pyrantel pamoate administered at the manufacturers' recommended dosages, and some foals were untreated. The overall efficacy for ivermectin was 33.5% (19 foals) and for moxidectin 47.2% (28 foals). Fenbendazole (16 foals) and pyrantel pamoate (21 foals) were highly effective for P. equorum each at 97.6%. For fenbendazole, 15 foals had 100% and for pyrantel pamoate 17 foals had >97% with 14 at 100%.
Animals↗