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PubMed2003

Heterologous antigen extract in ELISA for the detection of human IgE anti-Strongyloides stercoralis.

Strongyloides ratti larval extract was used for the standardization of ELISA to detect genus-specific IgE in human strongyloidiasis. Forty serum samples from monoinfected patients shedding S. stercoralis larvae (Group I), 40 from patients with other intestinal parasites (Group II), and 40 from copronegative healthy subjects (Group III) were analyzed. Genus-specific IgE levels (ELISA Index: EI) were significantly higher in the group I (EI = 1.43) than groups II (EI = 0.70) and III (EI = 0.71), showing positivity rates of 55%, 2.5% and 0%, respectively. Similarly, sera from copropositive patients had significantly higher levels of total IgE (866 IU/mL) as compared to those from group II (302 IU/mL) and III (143 IU/mL). A significant positive correlation was found between levels of Strongyloides specific-IgE and total IgE in sera from patients with strongyloidiasis. In conclusion, S. ratti heterologous extract showed to be a useful tool for detecting genus-specific IgE by ELISA, contributing for a better characterization of the immune response profile in human strongyloidiasis.

Animals↗
PubMed2004

Strongyloides ratti antigenic components recognized by IgE antibodies in immunoblotting as an additional tool for improving the immunodiagnosis in human strongyloidiasis.

IgE antibody response in human strongyloidiasis was evaluated by enzyme-linked immunosorbent assay (ELISA) and immunoblotting (IB) using Strongyloides ratti saline extract as heterologous antigen. A total of 50 serum samples of patients who were shedding S. stercoralis larvae in feces (group I, copropositive), 38 of patients with other intestinal parasites (group II), and 38 of subjects with negative results in three parasitologic assays (group III, copronegative) were analyzed. Levels of IgE anti-Strongyloides expressed in ELISA Index (EI) were significantly higher in patients of group I (1.32) than in group II (0.51) and group III (0.81), with positivity rates of 54%, 0%, and 10.5%, respectively. Fifteen S. ratti antigenic components were recognized in IB-IgE by sera of group I, with frequency ranging from 8% to 46%. In group II, only two antigenic bands (101, 81 kDa) were detected in a frequency of 10% and no reactivity was found in group III. Sera with EI values > 1.5 recognized five from 13 specific antigenic bands (70, 63, 61, 44, 7 kDa). It can be concluded that these five antigenic components recognized by IB-IgE using S. ratti antigen might be employed as an additional tool for improving the immunodiagnosis in human strongyloidiasis.

Animals↗
PubMed2002

Transmammary transmission of Strongyloides stercoralis in dogs.

Vertical transmission of larvae is a major pathway in the life cycle of several species of Strongyloides, but evidence for it occurring in humans or dogs with Strongyloides stercoralis is absent. In an effort to determine if vertical transmission could occur with S. stercoralis, each of 3 female dogs was infected with filariform larvae at a different stage of the reproductive cycle, i.e., preconception, gestation, or postpartum. Results showed that none of 6 pups born to a female infected before conception or any of 6 pups born to another female infected during gestation harbored any stage of S. stercoralis when necropsied at parturition. Conversely, all 5 pups that nursed from the female infected immediately postpartum became infected with adult S. stercoralis in their small intestines (range, 56-129 adult worms). Significantly, live filariform larvae of S. stercoralis were observed on 2 different occasions from milk samples taken from the lactating female. Because arrested development of larvae is not known in S. stercoralis, there is no reservoir of larvae in the parenteral tissues of females to queue for passage to the pups and, thus, it is not surprising that only timely infections, perhaps very late in gestation and during lactation, can be successful. These data support previous work in dogs with S. stercoralis, which concluded that vertical transmission through prenatal pathways does not occur, but they are the first from the dog to indicate that vertical transmission of this parasite through transmammary routes is possible. Whether transmammary transmission of S. stercoralis occurs in humans remains unknown but given its immense pathological potential, it should not be overlooked.

Animals↗
PubMed2006

Identification and characterization of the threadworm, Strongyloides procyonis, from feral raccoons (Procyon lotor) in Japan.

Strongyloides procyonis Little, 1966 was detected about 45 years ago in raccoons (Procyon lotor) of southern Louisiana, U.S.A., and was demonstrated experimentally to cause creeping eruption and a short-lived intestinal infection in a healthy human volunteer. After its description and demonstration of its pathogenicity in humans, S. procyonis has not been found in raccoons in North America despite repeated surveys. During a survey on feral raccoons in Japan, S. procyonis parasitic females were identified in 66 (28.3%) of 233 raccoons collected between May 2004 and January 2005. The number of parasitic females recovered from individual raccoons was 1-197 (geomean, 3.2). Both the morphological features and the nucleotide sequences of the small and large subunit ribosomal RNA genes (SSU/LSU rDNA) of S. procyonis closely resembled those of zoonotic Strongyloides stercoralis. The sequences of internal transcribed spacer (ITS)1 and 28S rDNA could differentiate clearly these 2 species. Awareness of S. procyonis in raccoons in North America and other places worldwide where raccoons are introduced and naturalized is important to assess the epidemiological significance of this potentially zoonotic helminth species.

Animals↗
PubMedDate not supplied

Transmission of Strongyloides steracolis person to person.

A case of presumed person-to-person transmission of Strongyloides steracolis is described. The index case was immunocompromised following high dose glucocorticosteroid therapy for myelodysplasia, which resulted in reactivation of latent strongyloides infection with the hyperinfestation syndrome. Physicians unfamiliar with this disease should realize that a history of foreign travel is unnecessary to acquire this parasite, and that transmission to persons in close proximity to the index case does occur and warrants treatment.

Aged↗
PubMed1998

Development of an in vitro culture method for harvesting the free-living infective larvae of Strongyloides venezuelensis.

An in vitro culture technique was established for harvesting Strongyloides venezuelensis free-living infective larvae using a nutrient broth medium as a substitute for rat-feces in polyvinyl culture bags (10 x 12 cm). The egg hatch rate (Y) in sterile saline at different incubation temperatures (X) was expressed as the quadratic function, Y = -0.192X2 + 8.673X - 19.550 (r = 0.901). The highest (100%) egghatch rate was observed at 25 degrees C. A significant difference (p < 0.05) in development rate (Y) of free-living infective larvae was observed between different concentrations of nutrient broth (X) which was highest (20.6%) in 0.12% nutrient broth concentrations, incubated at 20 degrees C for 5 days [Y = -864.032X2 + 245.995X - 0.560 (r = 0.875)]. Yields (Y) of infective larvae were observed relatively high when the culture medium was incubated at higher temperatures (X) which peaked at 25 degrees C (20.0%) than at lower temperatures, 15 degrees C (10.9%) and 20 degrees C (18.1%) [Y = -0.189X2 + 8.387X - 72.795 (r = 0.981)]. The period (Y) required for the development of infective larvae decreased with higher incubation temperatures (X) [Y = 0.035X2 - 2.025X + 32.375 (r = 0.995)]. The highest yield (19.2%) of infective larvae was obtained from culture bag inoculated with 15,000 eggs than with below and over 15,000 eggs in 0.12% nutrient broth and incubated at 25 degrees C for 4 days. The newly adapted culture method (from egg to third-stage larva) may be useful as a bio-bar/bioassay system for screening new chemical products, anthelmintics and pesticides, as well as for parasito-immunological studies with Strongyloides species.

Animals↗
PubMed1998

Viability of eggs, filariform larvae and adults of Strongyloides venezuelensis (Nematoda: Strongyloidea) maintained in vitro.

The present study was performed to check the viability of eggs, filariform larvae and adults of Strongyloides venezuelensis exposed to various conditions for an in vitro maintenance. The eggs in the feces remained viable for about 25 days at 4 degrees C and 15 days at room temperature. However, the isolated eggs in sterile saline lost their viability within 24 hr at 4 degrees C. The eggs in morula stage were very sensitive to air drying and rapidly lost their viability (< or = 12 hr). Filariform larvae survived for a maximum period of 45 days in fecal suspension and 28 days in 0.12% nutrient broth in polyvinyl culture bags maintained at 20 degrees C. On the other hand, those isolated from nutrient broth cultures survived for a maximum period of 32 days in tap water and 22 days in sterile saline at 20 degrees C. The mature adult worms obtained from experimentally infected rats survived maximally for 9 days in serum supplemented (10% rat-serum) 0.12% nutrient broth and 4 days in serum free nutrient broth at 37 degrees C while the culture media were changed at an alternate day. The adult female worms deposited fertile eggs in serum supplemented and serum free nutrient broth cultures, however, the hatched larvae (L1) were not able to develop to the filariform stage in the culture media and found to die within 24 hr of maintenance. The present findings on an in vitro maintenance of different stages of S. venezuelensis may provide useful information for biological and biochemical studies with Strongyloides species.

Animals↗
PubMed1977

Transmammary passage of Strongyloides sp. larvae in the human host.

The prevalence of infection with Strongyloides fuelleborni and hookworms (Ancylostoma duodenale and Necator americanus), and the possible transmammary passage of these parasites, was studied in the people of a village in Bulapé, Zaire, Africa. Stool examinations revealed that 34% of 76 infants under 200 days of age were infected with S. fuelleborni and 8% were infected with hookworms. Infection rates in the general population were 44% for S. fuelleborni and 90% for hookworms. The examination of milk from nursing mothers revealed the presence of Strongyloides larvae in one case. The finding suggests that S. fuelleborni may be transmitted via the milk in humans.

Adult↗
PubMed1995

Efficacy of stool examination for detection of Strongyloides infection.

To determine the efficacy of stool examination for detection of Strongyloides infection, 1,350 stool samples collected in Japan, Brazil, and Thailand were examined by four different methods (direct fecal smear, formalin-ether concentration. Harada-Mori filter paper culture, and agar plate culture). The newly developed agar plate culture method was highly effective; more than 96% of the positive cases were diagnosed by this method. The coprologic examination, however, was not sensitive enough for detecting chronic infections because more than 40% of the positive cases were overlooked even when persons with proven Strongyloides infection were re-examined several months later without intervening treatment. Therefore, it is essential to examine stool samples repeatedly to achieve a correct diagnosis, and even so, it is important to note that a negative result does not necessarily indicate the unequivocal absence of the infection.

Animals↗
PubMed2005

[Strongyloides stercoralis hyperinfection in a patient with acquired immunodeficiency syndrome].

Strongyloides stercoralis hyperinfection is a rare but know complication in patients with intestinal parasitism. Immunosuppressive therapy and acquires immunodeficiency syndrome (AIDS) are major risk factors for dissemination. Diagnosis requires identification of larvae in body fluids or biopsy and the mortality rates can be as high as 80%. The enteric bacteria are carried by invasive larvae and this can result in septicemia, pneumonia, meningitis, and disseminated bacterial infection in many parts of the body. We present a case of Strongyloides stercoralis hyperinfection complicated by Escherichia coli bacteraemia in a 45-year-old man African with AIDS.

AIDS-Related Opportunistic Infections↗
PubMed2004

Strongyloides robustus and the northern sympatric populations of northern (Glaucomys sabrinus) and southern (G. volans) flying squirrels.

Within North America, northern (Glaucomys sabrinus) and southern (Glaucomys volans) flying squirrels occupy distinct ranges with limited overlap. Sympatry in northern latitudes coincides with northern hardwood vegetation from Minnesota to New England. Strongyloides robustus is an intestinal parasite that infects both species but appears to be deleterious only to northern flying squirrels. As a result, S. robustus could be a critical determinant of flying squirrel population characteristics in at least some areas of sympatry. However, cold weather could potentially limit the distribution of S. robustus in northern climates. Therefore, we assessed fecal samples from both flying squirrel species to determine the presence of the nematode in Wisconsin. Strongyloides robustus was found in 12 flying squirrel scat samples and infected 52% of southern flying squirrels and 11% of northern flying squirrels. Prevalence of S. robustus infection for northern flying squirrels was substantially lower than previously reported from more southern regions. This is the northernmost documentation of S. robustus in flying squirrels and the first documentation of S. robustus parasitizing flying squirrels in Wisconsin.

Animals↗
PubMedDate not supplied

[The effect of lactation on the parasitism of rats by Strongyloides ratti (author's transl)].

In lactating females of many animal species infested by Nematoda, the self-cure is, if not suppressed, at least very distinctly delayed. It does not appear that an immunological deficiency is the cause of this. We show that this phenomenon also exists in lactating female rats with Strongyloides ratti parasites. In fact, for Strongyloides ratti, the maintenance of the worms is not the only notable modification determined by lactation; much more important is the decrease in the intensity of the parasitism. This aspect is not mentioned by writers who have only studied the different parasitic states in their final phase. Parallel to these alterations in the parasitism, the evolution of the corticosteronemy differs, from two points of view, from that described in infested virgin rats: --Suppression of the hypercorticosteronemy which normally appears 48 hours after infestation; --Attenuation of the hypocorticosteronemy which usually sets in from the tenth day of infestation. This opposition of lactation to the variations in the corticosteronemy induced by the worms is explained by the effect of lactation on the secretion of gluco-cortico-steroids, described under the term of "buffer effect of lactation". The decrease in the intensity of the parasitism may be explained by the fact that lactation, by preventing the hypercorticosteronemy normally caused by larval migration, permits the intervention of aspecific defences. As for the prolongation of the parasitism, it would seem to result on one hand, from a reduced solicitation of the means of defence owing to a smaller number of worms and, on another hand, from the slowing down of the hypocorticosteronemy through the buffer effect of lactation with all the consequences flowing from this at the level of the specific and aspecific defence reactions.

Adrenal Cortex Hormones↗
PubMed2000

[Fatal outcome of Strongyloides stercoralis infection in a patient with no previously known immunosuppression].

A case of fatal infection with Strongyloides stercoralis in a previously healthy young African with no known immunosuppression is reported. The patient suffered severe gastrointestinal bleeding and despite intensive treatment died of multiorgan failure. Postmortem, signs of ulcerating T-cell lymphoma were found in a jejunal specimen, and the patient was found to be infected with HTLV-1. Gastrointestinal bleeding in relation to infection with Strongyloides stercoralis is discussed as well as possible relations between the severity of infection, lymphoma and HTLV-1.

Adult↗
PubMed2002

[Immunodiagnosis of Strongyloides stercoralis infections in Chile using ELISA test].

BACKGROUND: Strongyloides stercoralis is a world wide distributed small intestinal nematode parasite. In immunocompetent individuals S stercoralis can produce asymptomatic infections or a moderate clinical picture of diarrhea, some cases become chronic. In immunocompromised patients, a disseminated disease may appear, sometimes fatal. In Chile, there is little epidemiological information about S stercoralis infections and appropriate diagnostic techniques are usually not used. AIM: To evaluate the yield of an ELISA test for the diagnosis of strongyloidiasis in Chilean patients. MATERIAL AND METHODS: Ten serum samples from patients with S stercoralis infections confirmed by a positive stool examination, 66 samples from individuals with other infections by tissue helminthes (24 toxocariasis, 15 trichinellosis, 11 hydatidosis, 12 fascioliasis and 4 cysticercosis), 13 samples from subjects with autoimmune diseases and 49 samples from apparently healthy individuals with a normal eosinophil count, were studied. ELISA antigen was prepared using a filariform larval extract obtained from a murine species of Strongyloides, maintained in laboratory animals. RESULTS: Using 0.33 optical density units as a cut off value, 9 of 10 sera of S stercoralis infected individuals, had a positive ELISA test. No cross reactions were observed with sera of patients with other helminthic infections, autoimmune diseases or in healthy individuals. Thus, specificity, positive and negative predictive values were 100%. CONCLUSIONS: The results obtained are similar with those found by other investigators. ELISA test for strongyloidiasis is a useful tool for the diagnosis of clinical cases and for seroepidemiological studies of this nematode infection in Chile.

Adult↗
PubMed2003

Prevalence of Strongyloides stercoralis infection in northeastern Thailand (agar plate culture detection).

UNLABELLED: The prevalence of Strongyloides stercoralis infection was studied in the rural and urban populations of 19 provinces of Northeastern Thailand. A total of 1233 fecal samples was collected from July to September 2002 and examined using agar plate culture method. The overall prevalence of S. stercoralis was 23.5 per cent with the highest infection rate in Kalasin Province (61.0%), predominantly among 60 year olds and older (28.0%), and in males (32.8%). The factors associated with Strongyloides infection were sex (males) and age (the over 19 year-old age group). CONCLUSION: S. stercoralis infection remains highly prevalent among the population of northeastern Thailand as confirmed by the agar plate culture method. The authors recommend that a program for effective strongyloidiasis control should have a justifiable priority.

Adult↗
PubMedDate not supplied

[Occurrence of Strongyloides stercoralis in patients with acquired immunodeficiency syndrome (AIDS)].

A comparative study on the occurrence of Strongyloides stercoralis larvae in 554 patients with AIDS and in 142 patients suffering from infectious diseases other than AIDS was conducted during the period from January 1987 to December 1988. The two groups was constituted by male individuals in-patients at Emílio Ribas Hospital--São Paulo. Faeces samples from 696 patients were submitted to spontaneous sedimentation method and Rugai method. The data obtained from the present investigation demonstrated a similar prevalence of Strongyloides stercoralis in both groups (p > 0.05) indicating no significant statistical differences.

AIDS-Related Opportunistic Infections↗
PubMed1992

Is the prevalence of HTLV-1 infection higher in Strongyloides carriers than in non-carriers?

To assess the concomitance of strongyloidiasis and HTLV-1 infection, an epidemiological survey was conducted in Okinawa, Japan, using the agar-plate culture, a highly sensitive method for detection of Strongyloides stercoralis. No significant difference in the positive rate of anti-HTLV-1 antibody was found between Strongyloides carriers and non-carriers. This result suggests that these two infections occur independently.

Adolescent↗
PubMed2004

Epidemiologic study of the association between human T-cell lymphotropic virus type 1 and Strongyloides stercoralis infection in female blood donors (Guadeloupe, French West Indies).

This case control study was conducted among female blood donors in Guadeloupe. A total of 85 HTLV-1 positive subjects were matched by age (+/- 5 years) in a 1:3 ratio to 255 HTLV-1 negative controls. The mean age was 48.5 and 48.9 years respectively. Ethnic, environmental and socio-economic risk factors were studied. Four risk factors were found independently associated with HTLV-1 seropositivity: Strongyloides stercoralis antibodies (OR = 3.6, CI 1.8, 7.3), low socio-economic status (OR = 2.0 CI 1.0, 4.0), low educational level (OR = 2.0 CI 1.0, 4.0) and agricultural activity (OR = 2.8 CI 1.4, 5.6). This logistic regression analysis demonstrates the reality of the association between HTLV-1 carriers and Strongyloides stercoralis, and its association with socio-economic and environmental risk factors.

Animals↗