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  1. Serological and molecular detection of Strongyloides stercoralis infection among an Orang Asli community in Malaysia
    Ahmad AF, Hadip F, Ngui R, Lim YA, Mahmud R
    Parasitol Res, 2013 Aug;112(8):2811-6.
    PMID: 23666229 DOI: 10.1007/s00436-013-3450-z
    Detection of Strongyloides stercoralis infection particularly in asymptomatic individuals is often hampered due to the lack of standard diagnostic tools. In this study, the use of serological and molecular approaches were investigated for the detection of S. stercoralis infection among an Orang Asli (indigenous) community following a preliminary detection by microscopic examination of faecal samples. Out of 54 individuals studied, 17/54 (31.5%) were detected to be positive for S. stercoralis infection by enzyme-linked immunosorbent assay (ELISA), compared to 0/54 (0%) by faecal examination. Further confirmation performed by a nested polymerase chain reaction (PCR) using DNA extracted from faecal samples of these 17 individuals yielded 3/17 (17.6%) positives for S. stercoralis DNA amplification. No amplification was seen with the other 37 faecal samples, which were negative by microscopy and ELISA. As the high ELISA positive results were suspected to be false-positives, ELISA is not recommended for use as a detection tool but may be beneficial for evaluating the effectiveness of anti-Strongyloides drugs. The present finding indicated that PCR should be considered as an alternative diagnostic tool for the detection of S. stercoralis infection.
    Matched MeSH terms: Strongyloidiasis/diagnosis
  2. Prevalence and risk factors of Strongyloides stercoralis infection among Orang Asli schoolchildren: new insights into the epidemiology, transmission and diagnosis of strongyloidiasis in Malaysia
    Al-Mekhlafi HM, Nasr NA, Lim YAL, Elyana FN, Sady H, Atroosh WM, et al.
    Parasitology, 2019 10;146(12):1602-1614.
    PMID: 31303180 DOI: 10.1017/S0031182019000945
    This cross-sectional study aimed to determine the prevalence and risk factors of S. stercoralis infection among 1142 Orang Asli primary schoolchildren in six different states of Peninsular Malaysia. Fecal samples were examined using direct smear, formalin-ether sedimentation (FES), agar plate culture (APC) and PCR techniques. Overall, 15.8% of the children were found to be infected with S. stercoralis. The prevalence was 0.2, 1.3, 15.2 and 13.7% by direct smear, FES, APC and PCR, respectively. Multivariate analysis showed that an age of >10 years, being male, belonging to a Proto-Malay tribe, belonging to the Senoi tribe, indiscriminate defecation, using an unimproved water source for drinking water and not wearing shoes when outside were the significant risk factors of infection among these children. In conclusion, we provide new evidence on the occurrence of S. stercoralis in Malaysia to show that there is a relatively high prevalence of infection among Orang Asli schoolchildren. Therefore, the use of specific methods for detecting S. stercoralis should be considered when screening these children for intestinal parasites. Moreover, prevention and control measures specific to S. stercoralis should be integrated into the intestinal parasitic infections control programme in Malaysia.
    Matched MeSH terms: Strongyloidiasis/diagnosis
  3. Direct detection of Strongyloides infection via molecular and antigen detection methods
    Balachandra D, Ahmad H, Arifin N, Noordin R
    Eur J Clin Microbiol Infect Dis, 2021 Jan;40(1):27-37.
    PMID: 32729057 DOI: 10.1007/s10096-020-03949-x
    Laboratory diagnosis of Strongyloides infections can be grouped into direct and indirect detection methods, and a combination of the two methods is often needed to reach an accurate and timely diagnosis. This review focuses on non-conventional direct detection via molecular and antigen detection assays. Conventional PCR is the most commonly used molecular diagnostic for Strongyloides. Real-time PCR is accurate and highly sensitive for quantitative and qualitative analysis. Meanwhile, PCR-RFLP can efficiently distinguish human and dog isolates of S. stercoralis, S. fuelleborni (from monkey), and S. ratti (from rodent). Loop-mediated isothermal amplification (LAMP) amplifies DNA isothermally with high specificity, efficiency, and rapidity, and has potential for point-of-care (POC) translation. As for antigen detection assay, coproantigen detection ELISAs for strongyloidiasis traditionally relied on raising rabbit polyclonal antibodies against the parasite antigens for use as capture or detection reagents. Subsequently, hybridoma technology using animals has enabled the discovery of monoclonal antibodies specific to Strongyloides antigens and was utilised to develop antigen detection assays. In recent times, phage display technology has facilitated the discovery of scFv antibody against Strongyloides protein that can accelerate the development of such assays. Improvements in both direct detection methods are being made. Strongyloides molecular diagnostics is moving from the detection of a single infection to the simultaneous detection of soil-transmitted helminths. Meanwhile, antigen detection assays can also be multiplexed and aptamers can be used as antigen binders. In the near future, these two direct detection methods may be more widely used as diagnostic tools for strongyloidiasis.
    Matched MeSH terms: Strongyloidiasis/diagnosis*
  4. Fulltext Serodiagnosis and early detection of Strongyloides stercoralis infection
    Arifin N, Hanafiah KM, Ahmad H, Noordin R
    J Microbiol Immunol Infect, 2019 Jun;52(3):371-378.
    PMID: 30482708 DOI: 10.1016/j.jmii.2018.10.001
    Strongyloidiasis is a major neglected tropical disease with the potential of causing lifelong infection and mortality. One of the ways for effective control of this disease is developing improved diagnostics, particularly using serological approaches. A serological test can achieve high diagnostic sensitivity and specificity, has the potential for point-of-care translation, and can be used as a screening tool for early detection. More research is needed to find clinically important antibody biomarkers for early disease detection, mapping, and epidemiological surveillance. This article summarizes human strongyloidiasis and the available diagnostic tools for the disease, focusing on describing the current antibody assays for strongyloidiasis. Finally, prospects of developing a more effective serodiagnostic tool for strongyloidiasis are discussed.
    Matched MeSH terms: Strongyloidiasis/diagnosis*
  5. Lateral Flow Dipstick Test for Serodiagnosis of Strongyloidiasis
    Yunus MH, Arifin N, Balachandra D, Anuar NS, Noordin R
    Am J Trop Med Hyg, 2019 08;101(2):432-435.
    PMID: 31218996 DOI: 10.4269/ajtmh.19-0053
    The conventional method of detecting Strongyloides stercoralis in fecal samples has poor diagnostic sensitivity. Detection of Strongyloides-specific antibodies increases the sensitivity; however, most tests are ELISAs that use parasite extract which may cross-react with the sera of other helminth infections. To improve the serological diagnosis of strongyloidiasis, this study aimed at developing a sensitive and specific lateral flow rapid dipstick test. Two recombinant proteins, recombinant NIE (rNIE) and recombinant Ss1a (rSs1a), were used in preparing the dipstick, with gold-conjugated antihuman IgG4 as detector reagent. In parallel, the corresponding ELISA was performed. Both assays demonstrated diagnostic sensitivity of 91.3% (21/23) when tested with serum samples of patients with Strongyloides infection, and 100% specificity with 82 sera of asymptomatic (healthy) and those with other parasitic infections. The ELISA and dipstick test results were positively correlated to each other (r = 0.6114, P = 0.0019). The developed lateral flow dipstick test may improve the serodiagnosis of strongyloidiasis and merit further validation studies.
    Matched MeSH terms: Strongyloidiasis/diagnosis*
  6. Evaluation of a Rapid IgG4 Lateral Flow Dipstick Test to Detect Strongyloides stercoralis Infection in Northeast Thailand
    Noordin R, Anuar NS, Juri NM, Wongphutorn P, Ruantip S, Kopolrat KY, et al.
    Am J Trop Med Hyg, 2021 07 08;105(3):688-691.
    PMID: 34237022 DOI: 10.4269/ajtmh.21-0317
    Strongyloides stercoralis affects more than half a billion people worldwide, and hyperinfection in immunocompromised patients can be fatal. Elimination of this neglected tropical disease requires field-applicable diagnostic tools. We conducted a laboratory evaluation of a lateral flow rapid dipstick test (SsRapid™) using sera samples from a Strongyloides-endemic area in northeast Thailand. Group 1 was S. stercoralis-positive and larvae- and/or antibody-positive (according to the IgG ELISA) (N = 100). Group 2 had negative fecal examination and IgG ELISA results (N = 25). Group 3 had other parasitic infections and negative IgG ELISA results (N = 25). The results showed good diagnostic sensitivity (82%) and excellent specificity (96%). Suggested improvements in the SsRapid™ test include increased diagnostic sensitivity and conversion to the more robust cassette format. Field studies should be performed as well.
    Matched MeSH terms: Strongyloidiasis/diagnosis*
  7. Fulltext A pentaplex real-time polymerase chain reaction assay for detection of four species of soil-transmitted helminths
    Basuni M, Muhi J, Othman N, Verweij JJ, Ahmad M, Miswan N, et al.
    Am J Trop Med Hyg, 2011 Feb;84(2):338-43.
    PMID: 21292911 DOI: 10.4269/ajtmh.2011.10-0499
    Soil-transmitted helminth infections remain a major public health burden in low- and middle-income countries. The traditional diagnosis by microscopic examination of fecal samples is insensitive and time-consuming. In this study, a pentaplex real-time polymerase chain reaction (PCR) was evaluated for the simultaneous detection of Ancylostoma, Necator americanus, Ascaris lumbricoides, and Strongyloides stercoralis. The results were compared with those obtained by conventional parasitological diagnostic methods. Real-time PCR was positive in 48 of 77 samples (62.3%) and microscopic examination was positive in six samples (7.8%) only (P < 0.05). In conclusion, the real-time PCR assay described in this study provides a specific and sensitive diagnostic tool for the detection of these four helminth species in epidemiological studies and monitoring of treatment programs.
    Matched MeSH terms: Strongyloidiasis/diagnosis*
  8. Fulltext Laboratory detection of strongyloidiasis: IgG-, IgG4 - and IgE-ELISAs and cross-reactivity with lymphatic filariasis
    Norsyahida A, Riazi M, Sadjjadi SM, Muhammad Hafiznur Y, Low HC, Zeehaida M, et al.
    Parasite Immunol., 2013 May-Jun;35(5-6):174-9.
    PMID: 23448095 DOI: 10.1111/pim.12029
    Enzyme-linked immunosorbent assays (ELISAs) were developed for the detection of IgG, IgG4 and IgE antibodies against Strongyloides stercoralis. A commercial ELISA (IVD Research, USA) was also used, and the sensitivities and specificities of the four assays were determined. Serum samples from 26 patients with S. stercoralis infection and 55 patients with other infections or no infection were analysed. Sensitivities of the IgG4 , IgG, IgE and IgG (IVD) assays were 76.9%, 84.6%, 7.7% and 84.6%, respectively, while the specificities were 92.7%, 81.8%, 100% and 83.6%, respectively. If filariasis samples were excluded, the specificities of the IgG4 -ELISA and both IgG-ELISAs increased to 100% and 98%, respectively. A significant positive correlation was observed between IgG- and IgG4 -ELISAs (r = 0.4828; P = 0.0125). IgG- and IgG- (IVD) ELISAs (r = 0.309) were positively correlated, but was not significant (P = 0.124). Meanwhile there was no correlation between IgG4 - and IgG- (IVD) ELISAs (r = 0.0042; P = 0.8294). Sera from brugian filariasis patients showed weak, positive correlation between the titres of antifilarial IgG4 and the optical densities of anti-Strongyloides IgG4 -ELISA (r = 0.4544, P = 0.0294). In conclusion, the detection of both anti-Strongyloides IgG4 and IgG antibodies could improve the serodiagnosis of human strongyloidiasis. Furthermore, patients from lymphatic filariasis endemic areas who are serologically diagnosed with strongyloidiasis should also be tested for filariasis.
    Matched MeSH terms: Strongyloidiasis/diagnosis*
  9. Fulltext Diagnostic Potential of an IgE-ELISA in Detecting Strongyloidiasis
    Ahmad H, Balachandra D, Arifin N, Nolan TJ, Lok JB, Hayat Khan A, et al.
    Am J Trop Med Hyg, 2020 12;103(6):2288-2293.
    PMID: 32996454 DOI: 10.4269/ajtmh.20-0265
    Strongyloides stercoralis infection is prevalent worldwide and can cause lifelong infection in immunocompetent individuals, and potentially death in immunosuppressed patients. The diagnosis is hindered by the low sensitivity of microscopic examination, thus making serology an important complementary test to improve the detection rate. However, there were reports that some Strongyloides-infected individuals were negative with specific IgG and IgG4 assays, and other helminth infections were positive with commercial Strongyloides IgG-ELISAs. Thus, there is a need to develop better serodiagnostic methods for strongyloidiasis. We investigated the diagnostic potential of IgE-ELISAs using Strongyloides larval lysate. Sera from two groups infected with Strongyloides served as the positive reference, that is, 1) positive by commercial IgG-ELISAs and IgG4 rapid test, and stool samples positive by microscopy and/or PCR (group IA; n = 20); and 2) negative by IgG-ELISAs and IgG4 rapid test, but stool samples were PCR positive (group IB sera; n = 11). Sera from another two groups served as negative reference (controls), that is, 1) infected with other parasites (group II; n = 73) and 2) healthy donors (group III; n = 22). Results showed a 100% diagnostic sensitivity in detecting sera from groups IA and IB. The latter group of individuals probably had early infection because their IgG and IgG4 assays were negative. The optical density values of group IB sera were also significantly lower than those of group IA (P < 0.003). The IgE-ELISA was 100% specific when tested against sera from groups II and III. This study highlights the diagnostic potential of IgE-ELISA using larval lysate to detect strongyloidiasis, especially those with probable early infection.
    Matched MeSH terms: Strongyloidiasis/diagnosis*
  10. Fulltext Strongyloides stercoralis induced bilateral blood stained pleural effusion in patient with recurrent Non-Hodgkin lymphoma
    Win TT, Sitiasma H, Zeehaida M
    Trop Biomed, 2011 Apr;28(1):64-7.
    PMID: 21602770
    Infections and mTalignancies are common causes of pleural effusion. Among infectious causes, hyperinfection syndrome of Strongyloides stercoralis may occur in immunosuppressive patient. A 62-year-old man, known case of Non-Hodgkin lymphoma (NHL) was presented with recurrent NHL stage IV and had undergone salvage chemotherapy. Patient subsequently developed pneumonia with bilateral pleural effusion and ascites. We reported rhabditiform larvae of S. stercoralis in pleural fluid of both lungs without infiltration by lymphoma cells. Stool for microscopic examination also revealed rhabditiform larvae of S. stercoralis. This patient was a known case of NHL receiving chemotherapy resulting in immunosuppression state. Although S. stercoralis infection is not very common compared to other parasitic infections, it is common in immunosuppressive patients and may present with hyperinfection. Therefore, awareness of this parasite should be kept in mind in immunosuppressive patients.
    Matched MeSH terms: Strongyloidiasis/diagnosis*
  11. Fulltext Detection of Strongyloides stercoralis infection among cancer patients in a major hospital in Kelantan, Malaysia
    Zueter AM, Mohamed Z, Abdullah AD, Mohamad N, Arifin N, Othman N, et al.
    Singapore Med J, 2014 Jul;55(7):367-71.
    PMID: 25091885
    INTRODUCTION: Strongyloidiasis is one of the most commonly neglected but clinically important parasitic infections worldwide, especially among immunocompromised patients. Evidence of infection among immunocompromised patients in Malaysia is, however, lacking. In this study, microscopy, real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assays (ELISAs) were used to detect Strongyloides stercoralis (S. stercoralis) infection among cancer patients in a Malaysian hospital.

    METHODS: A total of 192 stool and serum samples were collected from cancer patients who were receiving chemotherapy with or without steroid treatment at a hospital in northeastern Malaysia. Stool samples were examined for S. stercoralis using parasitological methods and real-time PCR. Serology by ELISA was performed to detect parasite-specific immunoglobulin G (IgG), IgG4 and immunoglobulin E (IgE) antibodies. For comparison, IgG4- and IgG-ELISAs were also performed on the sera of 150 healthy individuals from the same area.

    RESULTS: Of the 192 samples examined, 1 (0.5%) sample was positive for S. stercoralis by microscopy, 3 (1.6%) by real-time PCR, 8 (4.2%) by IgG-ELISA, 6 (3.1%) by IgG4-ELISA, and none was positive by IgE-ELISA. In comparison, healthy blood donors had significantly lower prevalence of parasite-specific IgG (2.67%, p < 0.05) and IgG4 (2.67%, p < 0.05) responses.

    CONCLUSION: This study showed that laboratory testing may be considered as a diagnostic investigation for S. stercoralis among immunocompromised cancer patients.
    Matched MeSH terms: Strongyloidiasis/diagnosis*
  12. Fulltext Symptomatic chronic strongyloidiasis in children following treatment for solid organ malignancies: case reports and literature review
    Norsarwany M, Abdelrahman Z, Rahmah N, Ariffin N, Norsyahida A, Madihah B, et al.
    Trop Biomed, 2012 Sep;29(3):479-88.
    PMID: 23018511
    Strongyloidiasis is an infection caused by the intestinal nematode Strongyloides stercoralis. Infected healthy individuals are usually asymptomatic, however it is potentially fatal in immunocompromised hosts due to its capacity to cause an overwhelming hyperinfection. Strongyloidiasis could be missed during routine screening because of low and intermittent larval output in stool and variable manifestations of the symptoms. We present two cases of strongyloidiasis occurring in children with solid organ malignancies suspected to have the infection based on their clinical conditions and treatment history for cancer. Both patients were diagnosed by molecular and serological tests and were successfully treated. Thus, strongyloidiasis in patients undergoing intensive treatment for malignancies should be suspected, properly investigated and treated accordingly.
    Matched MeSH terms: Strongyloidiasis/diagnosis*
  13. Fulltext Seroprevalence of fascioliasis, toxocariasis, strongyloidiasis and cysticercosis in blood samples diagnosed in Medic Medical Center Laboratory, Ho Chi Minh City, Vietnam in 2012
    Nguyen T, Cheong FW, Liew JW, Lau YL
    Parasit Vectors, 2016 09 05;9(1):486.
    PMID: 27595647 DOI: 10.1186/s13071-016-1780-2
    BACKGROUND: Despite the global effort against neglected tropical diseases (NTDs), developing countries with middle to low income are still burdened by them. Vietnam has been undergoing substantial economic growth and urbanization, but underprivileged people living in rural and suburban areas are still having little access to public health infrastructure and proper sanitation. Hitherto, limited information is available for seroprevalence and risk factors of several parasitic diseases in Vietnam.

    METHODS: A retrospective study was performed on diagnostic results of Fasciola spp., Toxocara spp., Strongyloides stercoralis and Taenia solium IgG ELISA tests from Medic Medical Center Laboratory, Ho Chi Minh City in 2012. The data were first stratified before statistical analyses were performed. Seroprevalence of fascioliasis, toxocariasis, strongyloidiasis and cysticercosis was determined and the age and gender risk factors were evaluated.

    RESULTS: Seroprevalence of fascioliasis, toxocariasis, strongyloidiasis and cysticercosis was 5.9 % (590/10,084; 95 % CI: 5.44-6.36), 45.2 % (34,995/77,356; 95 % CI: 44.85-45.55), 7.4 % (3,174/42,920; 95 % CI: 7.15-7.65) and 4.9 % (713/14,601; 95 % CI: 4.55-5.25), respectively. Co-exposure to multiple parasites was detected in 890 males (45.7 %; 95 % CI: 43.49-47.91) and 1,059 females (54.3 %; 95 % CI: 52.09-56.51). Social structure and differences in behavioural factors caused the gender factor to have a significant effect on the prevalence of all the diseases, while the seropositivity for fascioliasis and strongyloidiasis were age group-related.

    CONCLUSIONS: The seroprevalence of fascioliasis, toxocariasis, strongyloidiasis and cysticercosis in the blood samples diagnosed in Medic Medical Center Laboratory, Ho Chi Minh City, in year 2012 were comparatively high. The Vietnamese customs and cultures, dietary habits and agricultural practices exposed them to high risk of contracting NTDs. Despite the possibility of false positive results due to antigenic cross-reactions, detection of IgG antibodies remains as a reliable method in sero-epidemiological study as it is non-invasive and demonstrates previous exposure of individuals to the parasites. Besides the implementation of strategies to control these diseases, epidemiological analysis and surveillance of diseases should also be continually strengthened to monitor the effectiveness of regimens and interventions.

    Matched MeSH terms: Strongyloidiasis/diagnosis
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