Laboratory detection of strongyloidiasis: IgG‐, IgG₄‐ and IgE‐ELISAs and cross‐reactivity with lymphatic filariasis

Abstract

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.

Detection of Strongyloides stercoralis infection among cancer patients in a major hospital in Kelantan, Malaysia

“…In another study by our group involving samples from 26 immunocompetent patients with parasitologically proven infection and 55 control samples, Strongyloides IgG-ELISA was found to be significantly more sensitive but less specific than IgG4-ELISA (p < 0.05). (12) This suggests that the findings of two patients who were IgG4 negative but positive by IgG-ELISA and real-time PCR in our study could be attributed to the lower sensitivity of the IgG4 assay. Similarly, findings of patients who are negative by PCR and IgG4-ELISA but positive by IgG-ELISA may be explained by the lower specificity of the IgG assay.…”

“…To detect parasite-specific IgG4 and immunoglobulin E (IgE) antibodies, ELISA parameters were also optimised. (12) Flat-bottom polystyrene high-bind ELISA microwell plates (Nunc MaxiSorp; Nalge Nunc International, Rochester, NY, USA) were coated overnight at 4°C with 5 mg/mL of S. stercoralis L3 lysate antigen in 0.06 M carbonate buffer (pH 9.6) for IgG-ELISA, or with 10 mg/mL of the same antigen for IgG4-and IgE-ELISAs. All washings and incubations were performed on a microplate shaker placed in an incubator at 37°C.…”

Epidemiological Characteristics of Strongyloidiasis in Inhabitants of Indigenous Communities in Borneo Island, Malaysia

“…In this study, 11% serum specimens were ELISA positive. ELISA results show good sensitivity given that the study area is not endemic for filariasis as well as Schistosoma infection which is known to cross react with S. stercolaris [23]. However, potential cross reactions with other intestinal nematodes were of concern as the study area was also endemic for other intestinal nematodes [24,25].…”

Strongyloides stercoralis infection in transplanted patients

“…The parasite may also be found in the pleural and peritoneal fluid, mucinous cysts, lymph nodes, sputum and urine. Serological studies, including ELISA have a high sensitivity but a low specificity for strongyloides stercoralis infection [17]. Recently a novel real time PCR for the universal detection of strongyloides species was described [18] that is highly specific (100%) and may be helpful in some clinical settings.…”