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PubMed2003

Western blotting using Strongyloides ratti antigen for the detection of IgG antibodies as confirmatory test in human strongyloidiasis.

The present study was conducted to evaluate the frequency of antigenic components recognized by serum IgG antibodies in Western blotting (WB) using a Strongyloides ratti larval extract for the diagnosis of human strongyloidiasis. In addition, the WB results were compared to the enzyme-linked immunosorbent assay (ELISA) and the indirect immunofluorescence antibody test (IFAT) results. Serum samples of 180 individuals were analyzed (80 with strongyloidiasis, 60 with other intestinal parasitoses, and 40 healthy individuals). S. ratti was obtained from fecal culture of experimentally infected Rattus rattus. For IFAT, S. ratti larvae were used as antigen and S. ratti larval antigenic extracts were employed in WB and ELISA. Eleven S. ratti antigenic components were predominantly recognized by IgG antibodies in sera of patients with strongyloidiasis. There was a positive concordance for the three tests in 87.5% of the cases of strongyloidiasis. The negative concordance in the three tests was 94% and 97.5%, in patients with other intestinal parasitoses and healthy individuals, respectively. In cases of positive ELISA and negative IFAT results, diagnosis could be confirmed by WB. ELISA, IFAT, and WB using S. ratti antigens showed a high rate of sensitivity and specificity. In conclusion, WB using S. ratti larval extract was able to recognize 11 immunodominant antigenic components, showing to be a useful tool to define the diagnosis in cases of equivocal serology.

Adolescent↗
PubMed2003

Strongyloides venezuelensis alkaline extract for the diagnosis of human strongyloidiasis by enzyme-linked immunosorbent assay.

The present study was conducted to detected IgG antibodies using Strongyloides venezuelensis alkaline extract for the diagnosis of human strongyloidiasis by the enzyme-linked immunosorbent assay (ELISA). Sera from 90 subjects were analyzed (30 with strongyloidiasis, 30 with other parasites and 30 healthy individuals). Results were expressed in antibody titers, which were considered as positive when titer was >80. Sensibility and specificity of the assay were 100% and 96.7%, respectively. It can be concluded that the heterologous alkaline extract could be employed in ELISA as a diagnostic aid in human strongyloidiasis, due to its advantages as easiness of obtaining, practicability in preparing, and high indexes of sensitivity and specificity.

Animals↗
PubMed2003

Evaluation of techniques for the diagnosis of Strongyloides stercoralis in human immunodeficiency virus (HIV) positive and HIV negative individuals in the city of Itajaí, Brazil.

Human immunodeficiency virus (HIV) and intestinal parasites are common in Brazil. Previous studies have shown that infection with Strongyloides stercoralis is frequently associated with HIV infection. Strongyloidiasis is difficult to diagnosis and stool examination with conventional techniques fails to detect the helminth larvae. We made a prospective study, to test the efficacy of the agar plate technique to detect S. stercoralis in 211 HIV-positive patients and 213 HIV-negative patients in the city of Itajaí, Brazil, between September 2001 and June 2002. The feces samples of these patients were processed and analyzed according to the following methods: Lutz, formalin ethyl acetate, Baermann, Harada-Mori and agar plate culture. HIV-positive patients were more frequently infected by S. stercoralis (odds ratio= 5,.687). Among the methods used on fecal specimens, the larvae of S. stercoralis were most efficiently detected by the agar plate (69.7%) method, followed by the Baermann and the formalin ethyl acetate methods (48.5%) (P=0.01), Lutz (42.4%) (P=0.01), and Harada-Mori culture (24%) (P=0.001). Therefore agar plate culture is the most efficient method for the detection of S. stercoralis larvae and this technique should be the test of choice, especially in immunocompromised patients.

Adolescent↗
PubMed2000

Growth of the genital primordium as a marker to describe a time course for the heterogonic larval development in Strongyloides stercoralis.

A time course for the heterogonic development of Strongyloides stercoralis is described and a method for distinguishing the early larval stages of this nematode is proposed. The number of cells in the developing gonad were counted at various time intervals of incubation, along with the percentage of larvae in molt at each interval. The time course of growth of the gonad follows a pattern comparable to that reported for body length in an idealized general nematode. A model for the heterogonic development of S. stercoralis is proposed, which, although similar to other nematode developmental models, is stage specific for S. stercoralis, allowing the otherwise morphologically similar rhabditiform stages (L1, L2) to be distinguished.

Animals↗
PubMed1984

Influence of an experimental infection of Strongyloides ransomi on performance of pigs.

Sixty-four pigs (average 21.8 kg live weight) were divided into 16 comparable groups of four, each based on sex and body weight, to study the effects of a single infection of Strongyloides ransomi (either 0, 5,000, 10,000 or 20,000 S. ransomi larvae/kg body weight) on performance during a 91-d trial. Final weight, weight gain and average daily gain of pigs not infected were greater (P less than .01) than those of pigs given either 5,000 or 10,000 S. ransomi larvae/kg body weight, which in turn were greater (P less than .01) than those of pigs given 20,000 S. ransomi larvae/kg body weight. Average daily gain for pigs not infected was 40% greater (P less than .01) than that of pigs given 20,000 S. ransomi larvae/kg body weight. Feed required per unit of weight gain was 44% greater for pigs given 20,000 S. ransomi larvae/kg body weight than for pigs not infected, but this difference was not significantly greater due to extreme variation within the group of infected pigs. In each of two trials, eight crossbred barrows (average 20.0 kg in trial 1 and 22.7 kg body weight in trial 2) were examined for the effects of two levels of S. ransomi infections (0 and 10,000 larvae/kg body weight) on digestion and absorption of nutrients and on N balance. Digestion coefficients for dry matter, crude protein and gross energy for pigs not infected were greater (P less than .05) than for those experimentally infected.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Strongyloides stercoralis infections in the muscles of mice: a model for investigating the systemic phase of strongyloidiasis.

The sequence of events following infection of mice with the intestinal nematode, Strongyloides stercoralis, has been observed. Most infective larvae passed to the muscles where they did not develop further. In mice given primary infections, larvae were found in muscles for the first 9 d or so, then disappeared spontaneously. This was associated with an inflammatory reaction, predominantly eosinophilic and histiocytic in nature, around dying larvae. In mice exposed to the worms previously, both inflammation and worm destruction were hastened indicating the acquisition of resistance. A number of immunological parameters were measured in both primary and challenge infections. Specific antibodies of the IgM and IgG classes appeared, a marked immediate hypersensitivity reaction to injected antigen developed, and a transient blood eosinophilia occurred. No effects on phytohemagglutinin-induced spleen cell transformation were discerned, nor was transformation induced by specific antigen. It is concluded that this system provides a potentially useful model for investigating the systemic phase of strongyloidiasis, particularly with respect to assessing anthelmintic efficacy and the functions of fractionated antigens.

Animals↗
PubMed1999

Effects of in vitro culture methods on morphological development and infectivity of Strongyloides venezuelensis filariform larvae.

The effects of in vitro culture methods on morphological development and infectivity of Strongyloides venezuelensis filariform larvae (L3) to rats were investigated. A significantly higher body length was observed in L3 from filter paper culture (597.3 +/- 32.2 microns) than those in fecal (509.9 +/- 35.0 microns) and nutrient broth culture (503.3 +/- 31.0 microns) (P < 0.05). Larval infectivity was assessed by exposing rats to 1,000 L3 from each culture and worms were recovered from the lungs and small intestines. Recovery rate of these worms did not show any significant difference. A significantly greater body length of adults was recorded in those corresponding to the L3 harvested from filter paper (2,777.5 +/- 204.4 microns) and nutrient broth culture (2,732.5 +/- 169.8 microns) than those corresponding to the L3 obtained from fecal culture (2,600.5 +/- 172.4 microns) (P < 0.05). Although worm fecundity and EPG counts differed among culture methods but worm burdens and course of infection did not. These findings suggest that the methods of cultures have a significant effect on the morphological development of the larvae to the L3 stage, but do not influence the infectivity to rats.

Animals↗
PubMed1999

Partial cross-resistance between Strongyloides venezuelensis and Nippostrongylus brasiliensis in rats.

Rats were immunized through an initial infection with 1,000 filariform larvae (L3) of Nippostrongylus brasiliensis and after complete expulsion of worms they were challenged with 1,000 L3 of Strongyloides venezuelensis to investigate whether cross-resistance developed against a heterologous parasite. Nippostrongylus brasiliensis-immunized rats developed a partial cross-resistance against S. venezuelensis migrating larvae (MSL3) in the lungs and adult worms in the small intestine. The population of MSL3 in the lungs were significantly lower (P < 0.05) in immunized rats (22.0 +/- 7.4) compared with controls (105.0 +/- 27.6). The populations of adult worms, egg output and fecundity were initially decreased but from day 14 post-challenge they did not show any significant difference between immunized and control rats. However, the length of worm in immunized rat was revealed as retardation. Peripheral blood eosinophilia was significantly decreased (P < 0.05) on day 7 post-challenge and then gradually increased, which peaked on day 42 post-challenge when most of the worms were expelled. These results suggest that peripheral blood eosinophilia is strongly involved in the worm establishment and expulsion mechanisms.

Animals↗
PubMed1999

A case of Strongyloides stercoralis infection.

Strongyloidiasis has been recognized as one of the life-threatening parasitic infections in the immunocompromised patients. We report an intestinal infection case of Strongyloides stercoralis in a 61-year-old man. Rhabditiform larvae were detected in the stool examination and developed to filariform larvae having a notched tail through the Harada-Mori filter paper culture. The patient received five courses of albendazole therapy but not cured of strongyloidiasis.

Albendazole↗
PubMed2002

Persistent infection with Strongyloides venezuelensis in the Mongolian gerbil (Meriones unguiculatus).

To examine the fate of Strongyloides venezuelensis. Mongolian gerbils (Meriones unguicalatus) were orally infected with 1,000 L3 larvae per animal. Altogether, 50 gerbils divided into 5 groups of 10 each were monitored for a period of 570 days to document the kinetics of faecal egg output, adults worm population, morphological development, fecundity, and hematological changes including peripheral blood eosinophilia. This study chronicled a life long parasitism of S. venezuelensis in the gerbil host, and showed that S. venezuelensis infection was quite stable throughout the course of infection and the worms maintained their normal development as evidenced by their body dimension. A progressive loss of body condition of the infected gerbils was observed as the level of infection advanced. However, no detectable pathological changes were observed in the gastrointestinal tract. The present findings indicate that an immunocompetent host, such as the Mongolian gerbil, can serve as a life long carrier model of S. venezuelensis if the worms are not expelled within 570 days after infection.

Animals↗
PubMed2006

Strongyloides hyper-infection causing life-threatening gastrointestinal bleeding.

A 55-year old male patient was diagnosed with strongy-loides hyper-infection with stool analysis and intestinal biopsy shortly after his chemotherapy for myeloma. He was commenced on albendazole anthelmintic therapy. After initiation of the treatment he suffered life-threatening gastrointestinal (GI) bleeding. Repeated endoscopies showed diffuse multi-focal intestinal bleeding. The patient required huge amounts of red blood cells and plasma transfusions and correction of haemostasis with recombinant activated factor VII. Abdominal aorto-angiography showed numerous micro-aneurysms ('berry aneurysms') in the superior and inferior mesenteric arteries' territories. While the biopsy taken prior to the treatment with albendazole did not show evidence of vasculitis, the biopsy taken after initiation of therapy revealed leukoclastic aggregations around the vessels. These findings suggest that, in addition to direct destruction of the mucosa, vasculitis could be an important additive factor causing the massive GI bleeding during the anthelmintic treatment. This might result from substances released by the worms that have been killed with anthelmintic therapy. Current guidelines advise steroids to be tapered and stopped in case of systematic parasitic infections as they might reduce immunity and precipitate parasitic hyper-infection. In our opinion, steroid therapy might be of value in the management of strongyloides hyper-infection related vasculitis, in addition to the anthelmintic treatment. Indeed, steroid therapy of vasculitis with other means of supportive care resulted in cessation of the bleeding and recovery of the patient.

Animals↗
PubMed2000

A role of mast cell glycosaminoglycans for the immunological expulsion of intestinal nematode, Strongyloides venezuelensis.

We examined effects of mast cell glycosaminoglycans on the establishment of the intestinal nematode, Strongyloides venezuelensis, in the mouse small intestine. When intestinal mastocytosis occurred, surgically implanted adult worms could not invade and establish in the intestinal mucosa. In mast cell-deficient W/Wv mice, inhibition of adult worm invasion was not evident as compared with littermate +/+ control mice. Mucosal mastocytosis and inhibition of S. venezuelensis adult worm mucosal invasion was tightly correlated. To determine effector molecules for the invasion inhibition, adult worms were implanted with various sulfated carbohydrates including mast cell glycosaminoglycans. Among sulfated carbohydrates tested, chondroitin sulfate (ChS)-A, ChS-E, heparin, and dextran sulfate inhibited invasion of adult worms into intestinal mucosa in vivo. No significant inhibition was observed with ChS-C, desulfated chondroitin, and dextran. ChS-E, heparin, and dextran sulfate inhibited adhesion of S. venezuelensis adult worms to plastic surfaces in vitro. Furthermore, binding of intestinal epithelial cells to adhesion substances of S. venezuelensis, which have been implicated in mucosal invasion, was inhibited by ChS-E, heparin, and dextran sulfate. Because adult worms of S. venezuelensis were actively moving in the intestinal mucosa, probably exiting and reentering during infection, the possible expulsion mechanism for S. venezuelensis is inhibition by mast cell glycosaminoglycans of attachment and subsequent invasion of adult worms into intestinal epithelium.

Animals↗
PubMed2000

Role of IL-5 in innate and adaptive immunity to larval Strongyloides stercoralis in mice.

Protective immunity to Strongyloides stercoralis infective larvae in mice has been shown to be dependent on IL-5 based on mAb depletion studies. The goal of this study was to determine the functional role of IL-5 during the innate and adaptive immune response to larval S. stercoralis in mice. In these studies, three strains of mice were used: wild-type C57BL/6J (WT), IL-5 knockout (KO), and IL-5 transgenic (TG). Innate responses to the larvae indicated that there was enhanced survival in the KO animals and decreased survival in the TG animals compared with WT. Furthermore, killing of larvae in TG mice was associated with eosinophil infiltration and degranulation. In studying the adaptive immune response, it was observed that immunization of KO mice did not lead to the development of protective immunity. Experiments were then performed to determine whether KO mice reconstituted with Abs or cells could then develop protective immunity. KO mice displayed protective immunity via a granulocyte-dependent mechanism following injection of purified IgM from immune wild-type animals. Immunity in KO mice could also be reconstituted by the injection of eosinophils at the time of immunization. These eosinophils did not participate in actively killing the challenge infection, but rather were responsible for the induction of a protective Ab response. We conclude that IL-5 is required in the protective immune response for the production of eosinophils, and that eosinophils were involved in larval killing during innate immunity and in the induction of protective Abs in the adaptive immune response.

Animals↗
PubMed2006

Complement component C3 is required for protective innate and adaptive immunity to larval strongyloides stercoralis in mice.

This study examines the role of complement components C3 and C5 in innate and adaptive protective immunity to larval Strongyloides stercoralis in mice. Larval survival in naive C3(-/-) mice was increased as compared with survival in wild-type mice, whereas C3aR(-/-) and wild-type mice had equivalent levels of larval killing. Larval killing in naive mice was shown to be a coordinated effort between effector cells and C3. There was no difference between survival in wild-type and naive C5(-/-) mice, indicating that C5 was not required during the innate immune response. Naive B cell-deficient and wild-type mice killed larvae at comparable levels, suggesting that activation of the classical complement pathway was not required for innate immunity. Adaptive immunity was equivalent in wild-type and C5(-/-) mice; thus, C5 was also not required during the adaptive immune response. Larval killing was completely ablated in immunized C3(-/-) mice, even though the protective parasite-specific IgM response developed and effector cells were recruited. Protective immunity was restored to immunized C3(-/-) mice by transferring untreated naive serum, but not C3-depleted heat-inactivated serum to the location of the parasites. Finally, immunized C3aR(-/-) mice killed larvae during the adaptive immune response as efficiently as wild-type mice. Therefore, C3 was not required for the development of adaptive immunity, but was required for the larval killing process during both protective innate and adaptive immune responses in mice against larval S. stercoralis.

Animals↗
PubMed1976

Strongyloides fulleborni-like infections in man in Papua New Guinea.

During the course of a survey of intestinal parasites among the inhabitants of villages along the Fly River in the Kiunga region of Papua New Guinea, eggs of a Strongyloides species were found in the feces of several persons. In subsequent studies, 93 (17.8%) of 520 persons examined from five villages were found to be infected with this parasite. The examination of parasitic and free-living stages of the worm revealed that it is very similar to S. fulleborni, a parasite of monkeys, baboons and apes in Africa and Asia, although a definitive identification could not be made with the material available. Since non-human primates have apparently never inhabited New Guinea, the origin of these S. fulleborni-like infections is unknown.

Female↗
PubMed1982

Epidemiologic features of Strongyloides stercoralis infection in an endemic area of the United States.

The epidemiologic features of Strongyloides stercoralis infection in Kentucky were studied by an analysis of clinical cases at the University of Kentucky Medical Center (UKMC); by an analysis of parasitologic records of the Kentucky Bureau for Health Services (KBHS); and by a prospective stool survey of school children in Clay County, located in southeastern Kentucky, an area of the state previously found to be highly endemic for intestinal parasites. S. stercoralis was the most common parasitic infection diagnosed at UKMC. The patients were predominantly white male adults who were over 50 years old, had an associated chronic or debilitating medical illness, were of low socioeconomic background, and resided in southeastern Kentucky. S. stercoralis was a common parasitic infection at KBHS ad the patients showed a similar geographic distribution. Of 561 Clay County children surveyed, 23.7% harbored one or more intestinal parasite pathogens and 3.0% had S. stercoralis. Thus, S. stercoralis remains highly endemic in Kentucky and may cause disease even in geriatric patients.

Adolescent↗
PubMed1982

Strongyloides ratti and S. stercoralis: the effects of thiabendazole, mebendazole, and cambendazole in infected mice.

The effects of benzimidazole anthelmintics in murine strongyloidiasis were examined. Thiabendazole 50 mg/kg daily produced a 91% reduction in the numbers of Strongyloides ratti larvae in the feces. A similar suppression was seen when thiabendazole was given during the intestinal phase, but no effect was noted when the drug was administered during the phase of larval migration. Thiabendazole had no effect on larvae in the skin or lungs, did not inhibit maturation of worms, and did not expel adult worms from the gut, but did reduce fecundity of adult worms in the intestines by 84%. Mebendazole and cambendazole 50 mg/kg daily totally suppressed excretion of S. ratti in the feces. A similar suppression was seen when the two drugs were given during the phase of larval migration or during the intestinal phase. They had no effect on larvae in the skin, and the reduction in larval numbers in the lungs was not statistically significant. When given during the migratory phase and early intestinal phase, they reduced the numbers of fourth stage larvae recovered from the gut by 95%. Mebendazole and cambendazole totally eliminated intestinal adult worms. Dose response studies indicated that in terms of orally administered dose, cambendazole was 100-1,000 times more active than mebendazole. Thiabendazole and mebendazole had no significant effect on S. stercoralis larvae in the muscles. In contrast, cambendazole 50 mg/kg daily for 4 days eradicated S. stercoralis larvae from the muscles. It is concluded that cambendazole may have significant advantages over both thiabendazole and mebendazole in the treatment of strongyloidiasis.

Animals↗
PubMed1988

The immune response to nematode parasites: modulation of mast cell numbers and function during Strongyloides stercoralis infections in nonhuman primates.

Mucosal mast cell numbers are modulated in the intestines of rodents during parasitic infections. These mast cells can degranulate in response to worm antigens, and this event has been suggested to play a protective role for the host. To examine whether mast cells in higher animals play a role in protecting from disseminated parasitic disease, mast cell numbers and responsiveness to parasite antigens were evaluated in 5 Erythrocebus patas infected with the human intestinal nematode Strongyloides stercoralis. Initial infection and subsequent challenge infections were associated with increase in jejunal histamine and mast cell numbers, and these mast cells could release histamine in response to parasite antigens. Jejunal mast cell numbers returned to normal during a chronic phase of infection. The cells lost their ability to respond to antigenic stimulation following limited steroid treatment. Subsequent activation of chronic infections to fatal disseminated disease by more prolonged steroid treatment was associated with a marked decrease in jejunal mast cell numbers and histamine. In one animal which succumbed to severe disease without steroid treatment, jejunal mast cells were refractory to worm antigens.

Animals↗