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Strongyloidiasis is a neglected tropical disease that can cause fatal complications due to hyperinfection and disseminated strongyloidiasis in immunocompromised patients. We used two Strongyloides stercoralis recombinant antigenic proteins, L3NieAg.01 (NIE) and IgG-immunoreactive antigen (SsIR), to develop the recombinant antigen-based immunochromatography test (ICT) kit. We constructed and compared kits using either the NIE (NIE ICT kit) or the SsIR (SsIR ICT kit) antigens and a kit using a mixture of both (NIE-SsIR ICT kit) for detection of anti-Strongyloides IgG antibody in human serum samples. Serum samples from normal healthy individuals (Group I, n = 40), proven strongyloidiasis patients (Group II, n = 100), and those with other parasitic infections (Group III, n = 154) were evaluated. Sensitivity and specificity were 81.0% and 84.0% for the NIE ICT kit, 89.0% and 83.5% for the SsIR ICT kit, and 95.0% and 90.2% for the NIE-SsIR ICT kit, respectively. The NIE-SsIR ICT kit provided the best diagnostic results; it can supplement stool examination for clinical diagnosis and can be used to screen for asymptomatic S. stercoralis infection in people at risk in endemic areas. The NIE-SsIR ICT kit can also be used in large-scale sero-epidemiological investigations in endemic areas without the need for additional facilities or ancillary supplies.

Background. Amebic liver abscess (ALA) caused by Entamoeba histolytica is usually diagnosed based on its clinical symptoms, medical imaging abnormalities of the liver, and serological tests, the most common being the enzyme-linked immunosorbent assay (ELISA). For more than three decades, no investigation has evaluated the diagnostic performance of immunoglobulin G (IgG) subclasses in the serodiagnosis of ALA. Herein, we assessed the efficiencies of anti-amebic IgG and IgG subclasses for diagnosing ALA. Methods. A serological ELISA-based test was performed to assess its diagnostic performance using a total of 330 serum samples from ALA patients (nD14), healthy individuals (nD40), and patients with other diseases (nD276). Results. ELISA targeting the total IgG antibody to E. histolytica antigen exhibited 100% sensitivity 95% CI [76.8-100.0] and 97.8% specificity 95% CI [95.5-99.1], whereas the assay targeting IgG1 showed the same sensitivity (100% 95% CI [76.8-100.0]) and a slightly higher specificity (99.1% 95% CI [97.3-99.8]). The other IgG subclasses (IgG2, IgG3, and IgG4) displayed a lower sensitivity and specificity. The sensitivity and specificity did not significantly differ between tests measuring total IgG and IgG1 (Exact McNemar's test; p > 0.05), with a concordance of 98.2%, represented by a Cohen's kappa of 0.83 (p < 0.001), indicating almost perfect agreement. Conclusion. ELISA targeting IgG1 can provide valuable information to clinicians in differentiating ALA from other parasitic diseases, cancers, cirrhosis, and viral hepatitis. However, enzyme-conjugated anti-human total IgG is cheaper than anti-human IgG subclasses. Therefore, we suggest that total IgG-based ELISA is sufficient for the routine serodiagnosis of human ALA and possibly other clinical manifestations of invasive amebiasis. [ABSTRACT FROM AUTHOR]

Schistosoma mekongi infection is endemic in countries along the Mekong River and certain of its tributaries in the lower Mekong basin, especially in Lao People's Democratic Republic and Cambodia. Diagnosis of schistosomiasis is crucial before treatment and epidemiological surveys before and/or after an intervention, such as a mass drug administration. A newly developed immunochromatographic test (ICT) for the diagnosis of schistosomiasis mekongi, based on antiparasite antibody detection in human sera, was evaluated. The schistosomiasis mekongi-ICT (Smk-ICT) strip was developed using somatic antigen from adult S. mekongi. In total, 209 serum samples were examined, including 14 from parasitologically proven schistosomiasis mekongi patients, 30 from schistosomiasis japonica patients, other parasitosis (n = 135), and healthy volunteers (n = 30) from areas not endemic for S. mekongi. Eleven schistosomiasis mekongi samples were positive according to the Smk-ICT, whereas all healthy control samples were negative. Cross-reactions with paragonimiasis heterotremus, sparganosis, trichinellosis, and taeniasis saginata samples were observed at 2.4% (4/165). The diagnostic sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 78.6% (95% confidence interval [CI] 49.2–95.3), 97.6% (95% CI 93.9–99.3), 73.3% (95% CI 44.9–92.2), 98.2% (95% CI 94.7–99.6), and 96.1% (95% CI 92.1–98.4), respectively. The Smk-ICT kit might be useful to assess the prevalence of disease before establishing transmission control and mass deworming campaigns in countries in the Mekong River subregion. [ABSTRACT FROM AUTHOR]

Background Human opisthorchiasis, caused by Opisthorchis viverrini , is a public health problem in Southeast Asia and a major risk factor for cholangiocarcinoma. In Lao PDR, seroprevalence and the relationship between the number of O. viverrini eggs in infected people and specific antibody responses are still unknown. We evaluated and compared parasitological and serological screening methods in the community in an endemic area of opisthorchiasis in Lao PDR. Methods Seroprevalence of O. viverrini -specific total IgG and IgG4 antibodies and their relationships with O. viverrini egg intensities were evaluated in Khammouane Province, central Lao PDR, using ELISA and a modified formalin ethyl-acetate concentration technique (FECT). Results FECT stool examination revealed O. viverrini eggs in 70.3% (90/128) of individuals (95% CI 61.6 to 78.1%) while ELISA (based on total IgG and on IgG4 antibodies to O. viverrini) found 98.4% (95% CI 94.5 to 99.8%) and 89.8% (95% CI 83.3 to 94.5%) of sera, respectively. There was a positive and significant correlation between numbers of O. viverrini eggs per gram and levels of both IgG (R2=0.168, p<0.001) and IgG4 (R2=0.219, p<0.001) antibodies. Conclusions A high prevalence of human opisthorchiasis in Lao PDR was found using a new platform, serological screening in the community. This points to a need for sustainable control of this liver fluke infection. [ABSTRACT FROM AUTHOR]