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PubMed1983

Induction of immunity by transcolostrally-passed Strongyloides ransomi larvae in neonatal pigs.

Earlier studies had suggested that neonatal pigs that acquire infections of Strongyloides ransomi via the sow's milk fail to expel intestinal worms normally. Adult worm recoveries were compared from the intestines of normal and transcolostrally-infected neonatal pigs after a subcutaneous challenge inoculation of third-stage larve (L3) to determine whether a direct intestinal infection (via sow's colostrum) might affect resistance. Additionally, transcolostrally-infected pigs that had received an additional subcutaneous inoculation of L3 were reinoculated with L3, and the adult worm recoveries were compared to those of pigs immunized with only one subcutaneous inoculation of L3 to determine the effect of initial transcolostral infection on the development of protective immunity by this established procedure. The results showed that intestinal worms obtained transcolostrally can induce high resistance in pigs to reinfection by S. ransomi, and they do not affect the enhancement of protective immunity by a subcutaneous inoculation of L3. However, peripheral blood lymphocytes obtained from transcolostrally-infected pigs did not respond to larval antigens in vitro until after a subsequent subcutaneous inoculation of L3.

Animals↗
PubMed1983

Effects of preintestinal larval antigenic stimuli on the generation of intestinal immunity in Strongyloides ratti infection in rats.

Generation of intestinal immunity by antigenic stimulation with preintestinal, tissue-migrating larvae was investigated in the Strongyloides ratti-rat model. The results of daily fecal egg counts showed that the intestinal immunity against adult worms could be partially generated by priming with preintestinal migrating larvae. A further study demonstrated that this partial reduction of daily fecal egg count was mainly the result of inhibitory effects on the fecundity of the parasitic females, although the expulsion of the parasite from the gut could be advanced by several days. After tertiary immunization with preintestinal larvae, no significant potentiation in the protection was observed when compared with the rats treated by primary immunization alone.

Animals↗
PubMed1983

Immunization with infective larvae of Strongyloides ratti (Nematoda) exposed to microwave radiation.

Microwaves have not been tested previously for possible application in producing immunogenic preparations of parasites. This study examines the immunizing capacity of microwave-irradiated, infective larvae of Strongyloides ratti in rats. Rats were inoculated subcutaneously with untreated, microwaved, or microwaved and homogenized larvae, or distilled water, and challenged with untreated larvae. Data were collected on egg production and worm number/rat during primary infections and on egg production, worm number/rat, worm size, and eggs in utero/worm following challenge. Our results demonstrated that microwaved, infective larvae (intact or homogenized) of S. ratti were immunogenic for rats, even though they were incapable of reaching the intestine and maturing to adult worms. The immunity elicited by exposure to microwaved larvae was characterized on challenge by a significant reduction in the number of eggs produced/worm, by the formation of perioral plugs, and by reductions in worm numbers and size. These results suggest that microwave radiation may provide a valuable new tool for parasitic vaccine production. In addition, we have demonstrated the occurrence of a feature of the immune response of rats to S. ratti that may have been overlooked previously; i.e., a gut-level response that was elicited by larvae, but manifested against adult worms in the intestine.

Animals↗
PubMed1981

Induction of protective immunity to Strongyloides ransomi in pigs.

Pigs inoculated once or twice with infective Strongyloides ransomi larvae (L3) developed a strong protective immunity to challenge exposure. Intestinal expulsion of adult worms resulting from initial infection occurred 3 to 4 weeks after inoculation; worm loss reached 68% by 52 days after inoculation. Necropsy of pigs at various times after challenge exposure with infective L3 revealed that the majority of migrating L3 were eliminated before reaching the intestine; based on parasitic recoveries from the lung, the reduction was manifested as early as 48 hours after challenge exposure, Evidence for enhanced migration of L3 to the fat tissue in immune pigs could not be detected. Data indicate that infective L3 possess functional antigens capable of inducing protective immunity. Treatment of infected pigs with ivermectin was effective in removing arrested L3 in the subventral fat; 85% of these larvae were eliminated in 3 weeks. The role of milk-transmitted arrested L3 in the immunology of porcine strongyloidiasis is discussed.

Animals↗
PubMedDate not supplied

Diagnosis of Strongyloides stercoralis in sputum cytology.

A unique case of hyperinfection with Strongyloides stercoralis in an apparently immunosuppressed host is reported. The organism in various stages of maturation was initially detected by routine sputum cytology. Papanicolaou-stained smears from scrapings of jejunal and colonic mucosa provided specific confirmation of the parasite. Postmortem examination also showed massive tissue and vascular invasion in the intestine with cerebral and pulmonary dissemination.

Brain Abscess↗
PubMedDate not supplied

Strongyloides stercoralis in Papanicolaou-stained smears of ascitic fluid.

Filariform larvae of Strongyloides stercoralis were found by cytologic examination in Papanicolaou-stained smears of ascitic fluid in a renal transplant recipient treated with immunosuppressive drugs. The patient developed a fatal hyperinfection of S. stercoralis produced by an autoinfective cycle of the parasite.

Adult↗
PubMed1982

Antibodies to Strongyloides stercoralis larval surface antigens in chronic strongyloidiasis.

Antibodies to intact rhabditiform and filariform larvae of Strongyloides stercoralis were measured by indirect immunofluorescence using quantitative fluorescence microscopy. Forty-four of 48 sera from infected patients (92 per cent) were positive for IgG antibodies specific for surface antigens of filariform larvae. None of 30 North American adult control sera were positive. All sera from patients with Schistosoma mansoni, Loa loa, or hookworm infections or with idiopathic hypereosinophilia were negative. Three of nine sera from patients with Bancroftian filariasis were weakly positive. Pre- and posttreatment sera from seven patients were tested, and there was a marked decrease in antibody titers in all posttreatment sera. Twelve sera from infected patients were also tested for the presence of IgA and IgM antibodies specific for surface antigens of filariform larvae; all sera were negative for specific IgA, and only one exhibited a weak positivity for specific IgM. Nine of the IgG-positive sera were tested for the presence of IgA and IgG antibodies directed against surface antigens of S. stercoralis rhabditiform larvae. No parasite-specific IgA was detected in any of the sera, but most sera contained small amounts of parasite-specific IgG. We conclude that the majority of patients with chronic uncomplicated strongyloidiasis develop specific IgG antibodies directed against the surface of filariform larvae, the invasive stage of the parasite. such antibodies may be involved in host defenses that prevent fatal hyperinfection in immunocompetent individuals. In addition, our results confirm that the indirect immunofluorescence employing filariform larvae as antigen is a sensitive and specific test that may be a useful adjunct to stool examination in the diagnosis of strongyloidiasis.

Antibodies↗
PubMed1982

Stage-specific cross-resistance between Nippostrongylus brasiliensis and Strongyloides ratti (Nematoda) in rats.

Stage-specificity of cross-resistance between Nippostrongylus brasiliensis and Strongyloides ratti was investigated. Results showed that immunization with tissue-migrating larvae was sufficient to generate cross-resistance and that host defense mechanisms operating in the cross-resistance were directed against tissue-migrating larvae but not against intestinal adult worms. In addition, no significant potentiation of the cross-resistance was observed after multiple immunization. These observations suggest that host defense mechanisms against heterologous challenge infection were qualitatively and/or quantitatively different from those against homologous challenge infection.

Animals↗
PubMed1981

Protective role of immunoglobulin G in immunity to Strongyloides ratti.

Serum transfer from hyperimmune rats provided a significant degree of protection against Strongyloides ratti in mature, recipient rats. Eight immune serum pools tested were effective; however, the level of protection, as measured by challenge worm recoveries, ranged from 32 to 91%. Protection did not increase consistently with increasing volumes of immune serum, although as little as 5.0 ml/100 g of body weight afforded consistent protection against challenge infection. The protective effect was exerted against the early migrating tissue stages of the larvae; immune serum given 24 hr after challenge or later had no effect. The specificity of the immune serum's protection was suggested by the removal of this activity by absorption with heat-killed larvae, which have been shown to induce protection by immunization. Fractionation of immune serum showed that a heat-stable 7S component was responsible for protection; no protective activity could be detected in the 19S fraction. Further resolution of the 7S fraction by DEAE ion-exchange chromatography confirmed that the serum's protective activity was in the IgG component. The greatest protection was obtained with the fraction containing predominantly IgG1. In vitro sensitization of infective larvae with rat antibody failed to alter in vivo viability.

Animals↗
PubMed1981

[Parasitism and corticosteronemy in rats during repeated infestations with Strongyloides ratti].

The greater the number of larvae, the lower the possibilities of superinfestation when rats are repeated exposed to contact with Strongyloides ratti larvae, once a week or every two days for periods of up to twenty-four days: super-infestations occurs only on the 2nd day (10,000 larvae), the 4th day (5,000 larvae) and the 9th day (1,000 larvae). However, superinfestation continues throughout the entire duration of the experiment (46 days) when contamination is very low (10 larvae). Although there is now superinfestations, each new contact with larvae produces a hypercorticosteronemia reaction. Thus, the immunity acquired, although it is rapidly capable of preventing the larvae from reaching adulthood, does not prevent the larvae from beginning their migration and triggering the reaction. Progressively and slowly, this cortico-adrenal reaction decreases. It no longer takes place after 3 weeks of weekly infection by 10,000 larvae of after 2 weeks of bi-daily infection by 10,000 or 5,000 larvae. The reactional hypercorticosteronemia which follows an infestation does not intensify after repeated infections, whatever their frequency or intensity.

Animals↗
PubMed1981

[Cortico-adrenal reaction in rats to attempts of reinfestation by Strongyloides ratti (author's transl)].

After spontaneous recovery from infestation by Strongyloides ratti, reinfestation by a new generation of adult parasites is not possible if the primary infestation was by 5,000 or 10,000 larvae administered in one or more contacts and if the secondary infestation takes place 3 weeks after. Reinfestation becomes possible again 51 days after recovery from a primary infestation by 15,000 larvae. However although the larvae do not reach the adult stage, they do begin their migration and cause hypersecretion of gluco-cortico-steroids. There is thus a contrast between the ease with which the organism rapidly and lastingly prevents the transformation of larvae into adults and the difficulty in neutralising the larvae and preventing them from triggering a stress.

Adrenal Cortex↗
PubMed1980

Strongyloides stercoralis-like infection in a dog.

Helminths similar to Strongyloides stercoralis were recovered from the jejunum and ileum of a 6-month-old Boston Terrier that was shedding unusually large eggs, both unembryonated and embryonated, as well as first-stage larvae in fresh feces. Clinical signs included stunting, mucoid and blood-flecked feces, radiographic evidence of diffuse interstitial pulmonary infiltrate, focal dermatitis, and anemia. Decreased intestinal absorption of carbohydrate was found by means of the oral glucose and oral lactose tolerance tests. Serum protein and calcium values were decreased. At necropsy, histopathologic findings included uneven crypt hyperplasia and mild inflammation in the ileum and jejunum, diffuse interstitial pulmonary inflammation, Kupffer's cell hyperplasia in the liver, and generalized lymph node hyperplasia.

Animals↗
PubMed1980

Scanning electron microscopy of the penetration of newborn mouse skin by Strongyloides ratti and Ancylostoma caninum larvae.

The scanning electron microscopical appearances of infective larvae of Strongyloides ratti and Ancylostoma caninum have been described. Particularly noteworthy was the tail of S. ratti which was found to have a distal aperture surrounded by a row of eight projections. The penetration of larvae through newborn mouse skin was investigated. S. ratti larvae forced its way rapidly and directly through the stratum corneum. No larvae of A. caninum were observed in stages of partial penetration but the occasional empty sheath was seen.

Ancylostoma↗
PubMed1980

A re-assessment of the efficacy of febantel (Rintal) and fenbendazole (Panacur) against Strongyloides papillosus in sheep and goats.

An efficacy evaluation using febantel and fenbendazole was carried out against Strongyloides papillosus in sheep and goats in the Grootfontein area of South West Africa/Namibia. Three groups with five sheep and three goats in each group were artificially infested with this species. When the worms had reached the adult stage one group was treated with febantel, the other group with fenbendazole and the third group left as controls. Both anthelmintics were dosed at 5 mg/kg. All animals were sacrificed one week after treatment and total worm-counts carried out. Both anthelmintics were found to be highly effective.

Acetanilides↗
PubMed1994

Partial characterization of larval antigens of Strongyloides papillosus by western blot analysis.

Western blotting was used to analyse the antigens in extracts of adult and infective larvae (SIL) of Strongyloides papillosus with serum of infected rabbits. Several proteins in both the extracts reacted with immunoglobulin G in the serum. A protein of about 16 kDa in the extract of SIL showed an especially strong reaction. No cross-reaction was observed among proteins in the extracts of adult worms of such cattle helminths as Fasciola gigantica, Homalogaster paloniae, Trichuris discolor and Setaria digitata to S. papillosus-infected rabbit serum. The cuticle of the worms and substances in the worm tracks showed positive reaction with the immunoperoxidase test on SIL with the serum.

Animals↗
PubMed1994

Strongyloides stercoralis infestation masquerading as steroid resistant asthma.

A 42 year old man presented with steroid resistant asthma of 6 months duration. Serial chest radiographs showed migrating interstitial shadowing. Electrocardiographs showed decreasing R-wave progression in the precordial leads, and endomyocardial biopsy showed eosinophil infiltration with fibrosis. Bronchoscopy revealed inflammatory changes and lavage showed filariform larvae of Strongyloides stercoralis in the washings. This confirms the diagnosis of parasitic infection with eosinophilic cardiomyopathy.

Adult↗
PubMed1994

Chromosome complement, gametogenesis, and development of Strongyloides stercoralis.

Gametogenesis and development were studied in free-living adults of the human parasitic nematode Strongyloides stercoralis. The diploid chromosome number is 6 in germ-line tissue of females and in embryos that will develop into parasitic females. Reproduction appears to be by meiotic parthenogenesis and pseudogamy, as in other species in the genus. Fecundity may be limited by the short lifespan of males. Newly hatched larvae contain about 500 cells, whereas adult females have about 840 somatic cells and a variable number of germ-line cells. The apical vegetative zones of both ovary and testis are occupied by cells with large amounts of DNA in their nuclei.

Anaphase↗