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PubMedDate not supplied

Strongyloides stercoralis in routine Papanicolaou-stained sputum smears.

Three cases are reported in which the initial detection of unsuspected Strongyloides stercoralis infestation was made on Papanicolaou-stained smears of sputum submitted for routine cytopathology. All cases were subsequently confirmed by the examination of stool specimens. A common factor in the three cases was long-term treatment with corticosteroids for chronic respiratory disease. All three patients responded to treatment with antihelminthics. The significance of this parasite is discussed, and its appearance in Papanicolaou-stained smears is described and illustrated.

Adrenal Cortex Hormones↗
PubMed1998

Efficacy of an in-feed formulation of ivermectin against somatic larvae of Strongyloides ransomi in pregnant swine.

OBJECTIVE: To confirm that ivermectin fed for 7 days to pregnant sows controls transmission of Strongyloides ransomi larvae to pigs via the colostrum or milk. ANIMALS: 24 mixed-breed sows. PROCEDURE: The sows were infected with 250,000 S ransomi larvae on 3 occasions (days 63, 64, or 65, days 71 or 73, and days 78, 79, or 80 of gestation). Eight sows received ivermectin at a dosage of 100 micrograms of ivermectin/kg of body weight/d from days 92 to 99 of gestation, and 8 sows were treated from days 103 to 110 of gestation; 8 remaining sows received unmedicated vehicle. Numbers of S ransomi larvae were counted in samples of colostrum or milk collected 1, 2, and 7 days after parturition. At 7 and 14 days after parturition, fecal samples were collected from each sow and from 4 pigs from each litter for determination of nematode egg counts; at the latter date, pigs were euthanatized and necropsied for worm counting. RESULTS: Pigs born to ivermectin-treated sows had significantly (P < 0.01) fewer adult S ransomi than did those born to control sows; efficacy was 100%. Treated sows had significantly (P < 0.05) fewer S ransomi larvae in colostrum/milk samples taken 1, 2, and 7 days after parturition than did control sows; efficacy was 100%, with the exception of 1 S ransomi larva found in a milk sample from 1 treated sow at 2 days after parturition. CONCLUSION AND CLINICAL RELEVANCE: Ivermectin fed to sows during the last third of gestation at a dosage of 100 micrograms/kg/d for 7 consecutive days is highly efficacious for control of transmission of infective S ransomi larvae to pigs via colostrum or milk.

Animals↗
PubMed1998

Strongyloides stercoralis host-adapted third-stage larvae are the target of eosinophil-associated immune-mediated killing in mice.

Host-adapted, transformed, Strongyloides stercoralis third-stage larvae (L3+) were previously found to be antigenically different from free-living, infective, third-stage larvae (L3). These antigenic differences were reproduced by transformation of free-living larvae in tissue culture medium at 37 C over 24 hr. Transformed L3 of both derivations were given as challenge infections in diffusion chambers to naive mice and mice immunized with S. stercoralis L3. Within 12 hr, the challenge infections were killed regardless of whether the L3+ were generated in vitro or in vivo. Eosinophils, previously found to be important in the immune response to S. stercoralis larvae, were recruited into the L3+ microenvironment within 12 hr of challenge infection in immune mice, which supports the previously proposed mechanisms of S. stercoralis larval killing. Thus, S. stercoralis L3+ appear to be targets of the immune response in mice instead of being involved in immune evasion.

Animals↗
PubMed1998

Developmental switching in the parasitic nematode Strongyloides stercoralis is controlled by the ASF and ASI amphidial neurons.

Parasitic nematodes of the genus Strongyloides are remarkable for their ability to switch between alternative free-living developmental pathways in response to changing internal environmental conditions. After exiting the host, soil-dwelling larval stages may develop either to infectivity via 2 microbiverous stages (homogonic development) or to free-living adulthood via 4 microbiverous larval stages (heterogonic development). The progeny of these adults then give rise to the infective stage. In the latter case, free-living existence is extended in time and the number of infective larvae is greatly amplified. Anterior chemosensory neurons (amphidial neurons) are thought to respond to environmental cues and via signal transduction pathways control the direction of larval development. We now demonstrate by laser microbeam ablation that 2 classes of amphidial neurons (ASF and ASI), acting together, control the direction of free-living larval development. Larvae in which the neurons were killed developed to infectivity via the homogonic route rather than to adulthood via the otherwise predominant heterogonic route. These neurons are probable homologues of neurons ADF (=ASF) and ASI in Caenorhabditis elegans, suggesting the control of development at the cellular level is conserved among divergent taxa of nematodes. These observations also have important implications for the evolution of nematode parasitism and the design of new prophylactic measures against parasitic nematodes of medical and veterinary medical importance.

Animals↗
PubMed1998

Influence of rat strain on larval production by the parasitic nematode Strongyloides ratti.

The course of infection with Strongyloides ratti in a range of rat strains was assessed by monitoring the production of larvae. To our knowledge, this is the first such study of S. ratti using its natural host Rattus norvegicus. Host strain influenced the pattern of larval production. The results were qualitatively the same for 2 S. ratti lines of North American and Japanese origin.

Analysis of Variance↗
PubMed1978

Disseminated Strongyloides stercoralis infection. Association with ectopic ACTH syndrome and depressed cell-mediated immunity.

A patient with disseminated Strongyloides stercoralis was evaluated to elucidate host factors that may have led to the development of this infection. The patient was found to have oat cell carcinoma with hypercortisolism produced by tumor adrenocorticotropic hormone. His serum contained a potent inhibitor of lymphocyte blastogenesis. This patient's high level of endogenous cortisol may have impaired lymphocyte function and thereby facilitated infection with S stercoralis.

Adrenocorticotropic Hormone↗
PubMed1990

Strongyloides stercoralis. The cause of an urticarial-like eruption of 65 years' duration.

A 74-year-old woman with a history since childhood of skin eruptions and gastrointestinal problems was found to have peripheral eosinophilia. This finding was subsequently related to a chronic infection with the parasite Strongyloides stercoralis. This parasite is capable of autoinfection, which would account for the infection persisting for about 65 years. The intraduodenal habitat of S stercoralis and the negative results of numerous stool examinations promoted the use of the duodenal string test, which was diagnostic. A high index of suspicion should exist for patients from endemic regions in Southeast Asia and the Southeastern United States.

Aged↗
PubMed1989

Opportunistic Strongyloides stercoralis infection in lymphoma patients. Report of a case and review of the literature.

Strongyloides stercoralis is an intestinal parasite that may cause fatal opportunistic infections in immunocompromised patients. Herein is reported a patient who developed fatal disseminated strongyloidiasis 6 weeks after the initiation of chemotherapy for a large cell lymphoma of the small intestine. After reviewing the clinical and epidemiologic features of 16 other cases of disseminated strongyloidiasis in patients with malignant lymphomas, the currently available laboratory methods for the diagnosis of this parasite are outlined. Because uncomplicated infections are treatable, candidates for chemotherapy or immunosuppression with a relevant geographic history should be screened for S. stercoralis prior to the initiation of the treatment.

Antibodies↗
PubMed1979

Chromatin diminution and a chromosomal mechanism of sexual differentiation in Strongyloides papillosus.

Eggs obtained from feces of rabbits infected with Strongyloides papillosus were squashed and the karyotypes were determined. They contained cells with either two long and two medium sized chromosomes (2L2M), or one long, three medium and one short chromosome (L3MS). Two types of parasitic female gonad could be distinguished on the basis of oocyte chromosome morphology at prometaphase of the maturation division. All the oocytes in a gonad contained either two upaired long chromosomes and two unpaired medium sized chromosomes, or two unpaired medium sized chromosomes and two unpaired chromosomes segmented into beads in one region. At the maturation division in mitotic parthenogenesis the beads appear to be lost from one of the chromosomes. This generates a medium sized and a shorter chromosome, which together with the undiminished chromosomes make up the L3MS karyotype. Animals with beaded oocyte chromosomes lay eggs that develop into males. It is suggested that males are heteromorphic for the long homologue due to chromatin diminution, that occurs in the maturation division of mitotic parthenogenesis.

Animals↗
PubMed1988

Kinetic study of mast-cell growth factor production by lymphocytes during the course of Strongyloides ratti infection in mice.

Mast-cell growth factor (MCGF) activity in the media conditioned by mesenteric lymph node or spleen cells from Strongyloides ratti-infected C57BL/6 mice was examined by using factor-dependent cell line FDC-P2 or bone marrow-derived, cultured mast cells (BMMC) as indicators. Mesenteric lymph node cells from infected mice spontaneously released MCGF activity by culturing for 24 h, showing peak production on days 5-7. MCGF production by mesenteric lymph node cells was augmented after stimulation with adult worm antigen or with concanavalin A (con A). The peak of MCGF production by antigen-stimulated lymph node cells was observed on days 5-7 and declined thereafter. MCGF production by antigen-stimulated spleen cells was lower than that by lymph node cells and reached a peak on day 7 or later. Normal lymph node or spleen cells did not produce MCGF activity even after stimulation with adult worm antigen. The peak of MCGF production by mesenteric lymph node cells preceded the peak of intestinal mastocytosis at the infected site by 4-6 days. The cells producing MCGF had a phenotype of Thy-1+, L3T4+, and Lyt-2-. The possible importance of mucosal mast cells in worm expulsion is discussed.

Animals↗
PubMed1981

Strongyloides stercoralis hyperinfection: sequential changes of gastrointestinal radiology after treatment with thiabendazole.

Sequential changes of gastrointestinal radiology are described in a case of Strongyloides stercoralis hyperinfection. Duodenal dilatation, reflux of barium into the biliary and pancreatic duct, and mucosal thickening of the small intestine were the striking features before treatment. Although treatment with thiabendazole led to rapid and complete clearance of rhabditiform larvae, some abnormal radiologic changes in the small intestine persisted for approximately 4 months before the mucosal pattern reverted to normal.

Female↗
PubMed1983

Radiological manifestations of Strongyloides stercoralis.

Nine patients with radiological changes due to Strongyloides stercoralis (SS) are described. A wide variation in appearance exists ranging from mild edema of the duodenal and small bowel mucosa to grossly enlarged, prominent valvulae conniventes. Small bowel dilatation is significant, and in overwhelming infestation toxic dilatation with paresis results. Spasm, ulceration, and stricture are encountered in addition. The appearances usually improve and reverse with treatment. Ampullary involvement is responsible for reflux of barium into the pancreatic duct and biliary tree through a patulous sphincter. In 1 patient the colonic changes resembled ulcerative colitis.

Adult↗
PubMed2002

An Update on the Geohelminths: Ascaris lumbricoides, Hookworms, Trichuris trichiura, and Strongyloides stercoralis.

Geohelminths remain prevalent throughout the developing world where levels of sanitation, personal hygiene, and maternal education are low. The five species of nematodes responsible for the bulk of disease are Ascaris lumbricoides, the hookworms Ancylostoma duodenale and Necator americanus, Trichuris trichiura, and Strongyloides stercoralis. Geohelminths are acquired through ingestion of fecally contaminated food or water or through contact with infected soil. In developing countries, infection with more than one nematode species and high worm burdens are common. The morbidity is substantial, particularly among children, and deaths occur. Geohelminthic infections are encountered in industrialized countries among immigrants and long-term travelers who have lived in endemic regions where sanitation is poor, and occasionally following autochthonous transmission.

Journal Article↗
PubMed1992

Strongyloides stercoralis hyperinfection in a carrier of HTLV-I virus with evidence of selective immunosuppression.

A patient with near fatal Strongyloides hyperinfection syndrome is briefly described. Investigation for possible risk factors for this parasitic infection disclosed that he was a carrier of human T-cell leukemia virus type I (HTLV-I), but without evidence of disease due to this retrovirus. Over the next few years, the patient's serum antibody levels of IgG to S. stercoralis larvae declined and became undetectable despite continued infection with the parasite. Repeated courses of appropriate treatment cleared the parasitic infection only temporarily. The patient was also found to have undetectable total serum IgE and a negative immediate hypersensitivity skin test to S. stercoralis antigens. Five of six other patients with HTLV-I-associated disease and with or without strongyloidiasis were also found to have very low total serum IgE levels. It is postulated that HTLV-I infection in certain individuals may selectively impair immune responses that are critical in controlling strongyloidiasis.

Antibodies, Helminth↗
PubMed1993

Mucosal mast cells and the expulsive mechanisms of mice against Strongyloides venezuelensis.

The possible importance of mucosal mast cells in the expulsive mechanisms of mice against Strongyloides venezuelensis was examined. After a primary infection by subcutaneous inoculation with various doses into C57BL/6 mice, about 50% of the initial dose of infective larvae (L3) became adult worms and, regardless of the dose of infection, they were completely expelled by Day 12 with similar kinetics. Intestinal mastocytosis at the time of expulsion was comparable among groups given different doses of infection. A kinetic study after infection with 2000 L3 in C57BL/6 mice revealed that mastocytosis started from Day 8, rapidly reached a peak on Day 12, and then gradually decreased. The strongest mastocytosis was observed in the upper one sixth of the small intestine where the majority of adult worms parasitized. Over 80% of mast cells induced by the infection were located in the intestinal epithelial layer. When mast cell-deficient W/Wv and their normal littermate +/+ mice were infected with 1000 L3, expulsion was significantly delayed in W/Wv mice, though adult worms were eventually expelled by Day 18 in W/Wv mice. Delayed expulsion as well as defective mast cell responses of W/Wv mice were completely restored by bone marrow grafting 10 weeks prior to infection. These results show that, like S. ratti infection, intestinal mucosal mast cells are important in causing expulsion of S. venezuelensis.

Animals↗
PubMed1988

The effects of thiabendazole, mebendazole and cambendazole in normal and immunosuppressed dogs infected with a human strain of Strongyloides stercoralis.

The effects of three benzimidazole anthelmintics in dogs infected with a human strain of Strongyloides stercoralis were investigated. Cambendazole, but not thiabendazole or mebendazole, abrogated the subsequent development of a patent infection when administered at the same time as infection to immunocompetent dogs. None of the drugs eradicated infection when given after the onset of patency in immunosuppressed animals, although worm burdens were greatly reduced in dogs treated with cambendazole. The implications of these findings for the treatment of patients with strongyloidiasis, particularly those with disseminated infections, are discussed.

Animals↗
PubMed1989

Concurrent infections with Strongyloides and T-cell leukemia virus and their possible effect on immune responses of host.

Sera from 91 patients with strongyloidiasis in Okinawa prefecture, Japan, were examined for the presence of the concurrent infection with adult T-cell leukemia (ATL) virus by detecting the antibody to ATL-associated virus antigen (anti-ATLA). As high as 73.6% of the patients were found to be positive for the anti-ATLA antibody, whereas in 38 Strongyloides-negative controls, the positive rate was only 18.4% A significant increase of OKT 4+ cells and a decrease of OKT 8+ cells were noted among the patients positive for anti-ATLA antibody. A considerable rise of spontaneous proliferation of peripheral lymphocytes and a depression of mitogen-induced proliferative responses were also found in the patients. The increase of background mitogenesis was considered to be due to the concurrent infection with the ATL virus, but the depressed responses to mitogenic stimuli seemed to have no relation with the presence of the viral infection. The possible contribution of strongyloidiasis as a cofactor predisposing to ATL viral infection or leading the virus carriers to ATL patients was discussed.

Adult↗
PubMed1986

Strongyloides stercoralis: immunobiological considerations on an unusual worm.

In the highly competitive world of parasites, where survival is indissolubly tied to the presence of suitable hosts in the same ecological niche, Strongyloides stercoralis occupies a unique position. This versatile nematode has developed a successful relationship with two ecosystems, the terrestrial environment and the mammalian body, by becoming facultatively independent of either (Box 1). It requires external maturation for transmission, but it also has the ability to multiply within a single host. It prefers man, but may infect apes, monkeys, dogs and cats. As a human parasite, S. stercoralis establishes self-perpetuating intestinal colonies and negotiates their survival with the host's defense mechanisms. In this article, Robert Genta reviews the immunobiological aspects of this unusual relationship.

Journal Article↗