scholarly journals Comparative Accuracy of the InBios Scrub Typhus Detect IgM Rapid Test for the Detection of IgM Antibodies by Using Conventional Serology

2015 ◽  
Vol 22 (10) ◽  
pp. 1130-1132 ◽  
Author(s):  
Hugh W. F. Kingston ◽  
Stuart D. Blacksell ◽  
Ampai Tanganuchitcharnchai ◽  
Achara Laongnualpanich ◽  
Buddha Basnyat ◽  
...  
Keyword(s):  
Rapid Diagnostic Test ◽  
Scrub Typhus ◽  
Specific Antigen ◽  
Rapid Test ◽  
Febrile Illness ◽  
High Specificity ◽  
Immunofluorescence Assay ◽  
Serum Samples ◽  
Igm Antibodies ◽  
Comparative Accuracy

ABSTRACTThis study investigated the comparative accuracy of a recombinant 56-kDa type-specific antigen-based rapid diagnostic test (RDT) for scrub typhus for the detection of IgM antibodies by using conventional serology in well-characterized serum samples from undifferentiated febrile illness patients. The RDT showed high specificity and promising comparative accuracy, with 82% sensitivity and 98% specificity for samples defined positive at an IgM indirect immunofluorescence assay positivity cutoff titer of ≥1:1,600 versus 92% and 95% at ≥1:6,400, respectively.

scholarly journals Diagnostic Accuracy of the InBios Scrub Typhus Detect™ ELISA for the Detection of IgM Antibodies in Chittagong, Bangladesh

2018 ◽  
Vol 3 (3) ◽  
pp. 95 ◽  
Author(s):  
Stuart Blacksell ◽  
Hugh Kingston ◽  
Ampai Tanganuchitcharnchai ◽  
Meghna Phanichkrivalkosil ◽  
Mosharraf Hossain ◽  
...  
Keyword(s):  
General Population ◽  
Diagnostic Accuracy ◽  
Diagnostic Tests ◽  
Scrub Typhus ◽  
Febrile Illness ◽  
High Sensitivity ◽  
Immunofluorescence Assay ◽  
Immunoglobulin M ◽  
Regional Assessment ◽  
Igm Elisa

Here we estimated the accuracy of the InBios Scrub Typhus Detect™ immunoglobulin M (IgM) ELISA to determine the optimal optical density (OD) cut-off values for the diagnosis of scrub typhus. Patients with undifferentiated febrile illness from Chittagong, Bangladesh, provided samples for reference testing using (i) qPCR using the Orientia spp. 47-kDa htra gene, (ii) IFA ≥1:3200 on admission, (iii) immunofluorescence assay (IFA) ≥1:3200 on admission or 4-fold rise to ≥3200, and (iv) combination of PCR and IFA positivity. For sero-epidemiological purposes (ELISA vs. IFA ≥1:3200 on admission or 4-fold rise to ≥3200), the OD cut-off for admission samples was ≥1.25, resulting in a sensitivity (Sn) of 91.5 (95% confidence interval (95% CI: 96.8–82.5) and a specificity (Sp) of 92.4 (95% CI: 95.0–89.0), while for convalescent samples the OD cut-off was ≥1.50 with Sn of 66.0 (95% CI: 78.5–51.7) and Sp of 96.0 (95% CI: 98.3–92.3). Comparisons against comparator reference tests (ELISA vs. all tests including PCR) indicated the most appropriate cut-off OD to be within the range of 0.75–1.25. For admission samples, the best Sn/Sp compromise was at 1.25 OD (Sn 91.5%, Sp 92.4%) and for convalescent samples at 0.75 OD (Sn 69.8%, Sp 89.5%). A relatively high (stringent) diagnostic cut-off value provides increased diagnostic accuracy with high sensitivity and specificity in the majority of cases, while lowering the cut-off runs the risk of false positivity. This study underlines the need for regional assessment of new diagnostic tests according to the level of endemicity of the disease given the high levels of residual or cross-reacting antibodies in the general population.

scholarly journals Diagnostic evaluation of IgM ELISA and IgM Immunofluorescence assay for the diagnosis of Acute Scrub Typhus in central Nepal

2020 ◽  
Author(s):  
Rajendra Gautam ◽  
Keshab Parajuli ◽  
Tshokey Tshokey ◽  
John Stenos ◽  
Jeevan Bahadur Sherchand
Keyword(s):  
Likelihood Ratio ◽  
Predictive Value ◽  
Gold Standard ◽  
Scrub Typhus ◽  
Febrile Illness ◽  
Immunofluorescence Assay ◽  
Acute Febrile Illness ◽  
Central Nepal ◽  
Igm Elisa ◽  
Typhus Fever

Abstract Introduction Scrub typhus is an acute febrile illness caused by the obligate intracellular bacterium,Orientia tsutsugamushi. Given their affordability and ease of use, antibody based diagnostic assays can be important diagnostic tools for early detection of scrub typhus fever in resource poor countries like Nepal. Immunochromatography (ICT) and IgM ELISA are two of the routinely employed antibody based assays for diagnosis of Scrub typhus fever in Nepal, although the recommended gold standard diagnostic test is IgM Immunofluorescence assay (IFA). This study evaluated the InBios Scrub Typhus Detect™ Immunoglobulin M (IgM) ELISA and IgM Immunofluorescence assays in single serum sample at the time of admission. Methodology Study participants (1585 suspected cases), were enrolled based on acute febrile illness with suspected scrub typhus cases in central Nepal from April 2017 to March 2018. Blood sample was collected from the suspected patients of scrub typhus, presenting with acute febrile illness. IgM antibody to Orientia tsusugamushi was detected by using Scrub Typhus Detect™ Kit (In Bios International, USA) and an in-house IgM IFA (Australian Rickettsial Reference Laboratory, Geelong, Australia. The IFA assay was performed with the Gilliam, Karp, Kato strains and O. chuto antigens following the ARRL protocol. Result Statistical analysis of ELISA IgM results when compared to reference test, IgM IFA results demonstrated the following characteristics, sensitivity 84.0% (95%CI: 79.73%-87.68%), specificity 94.82% (95% CI: 93.43%-95.99%), positive likelihood ratio 16.21% (95% CI: 12.71%-20.67%), negative likelihood ratio 0.17% (95% CI: 0.13-0.21%), disease prevalence 22.08% (95% CI: 20.06%-24.21%), positive predictive value 82.12% (95% CI: 78.28-85.42%) and negative predictive value 95.44% (95% CI: 94.27%-96.38%) respectively. Conclusion The study indicated that the IgM ELISA has the sensitivity 84.0% (95% CI: 79.73%-87.68%) and specificity 94.82% (95% CI: 93.43%-95.99%). Although IgM IFA is considered the gold standard test for the diagnosis of scrub typhus cases, it is relatively expensive, requires trained personal and a microscope with fluorescence filters. Scrub typhus IgM ELISA with appropriate OD cut–off values may be the best alternative test and possible viable option for resource limited endemic countries like Nepal.

scholarly journals Variables associated with the prevalence of anti-Leishmania spp. antibodies in dogs on the tri-border of Foz do Iguaçu, Paraná, Brazil

2018 ◽  
Author(s):  
Renata Cristina Ferreira Dias ◽  
Vanete Thomaz-Soccol ◽  
Aline Kuhn Sbruzzi Pasquali ◽  
Silvana Maria Alban ◽  
Ricardo Cancio Fendrich ◽  
...  
Keyword(s):  
Rapid Test ◽  
Immunofluorescence Assay ◽  
Confirmatory Test ◽  
Serum Samples ◽  
Leishmania Spp ◽  
Confirmatory Analysis ◽  
The City ◽  
Public Collection ◽  
Geographical Characteristics ◽  
Immunoenzymatic Assay

Abstract The aim of this study was to investigate the occurrence of anti-Leishmania spp. antibodies in dogs from localities in the city of Foz do Iguaçu, Paraná state, Brazil, on the border with Argentina and Paraguay. Blood samples dogs were collected to perform the following serologic tests: immunochromatographic DPP® rapid test, indirect immunoenzymatic assay (ELISA) and indirect immunofluorescence assay (IFA). In 2012, 285 dogs were analyzed on Argentina border, and in 2013, serum samples from 396 dogs on the border of Paraguay were collected. Using ELISA for screening and IFA for the confirmatory test, the results showed that the antibody prevalence was 1.8% (5/285) on the border of Argentina and 3.0% (12/396) on Paraguay border. When using the DPP® for screening and ELISA as a confirmatory analysis, we observed a seroreagent prevalence in dogs of 2.5% (7/285) on Argentina border and 5.1% (20/396) on Paraguay border. The non-public collection of domestic waste (p= 0.0004) was shown to be associated with leishmaniasis. This study shows the presence of leishmaniasis and suggest the emergence of canine visceral leishmaniasis in state of Paraná due to the confirmed occurrence of seroreactive dogs on Argentina and Paraguay border, which has environmental and geographical characteristics that favor the spread of the parasite.

Serum Adsorption Study to Validate the Specificity of a Rapid Test to Detect Strongyloides stercoralis Infection

2021 ◽  
Author(s):  
Rahmah Noordin ◽  
Emelia Osman ◽  
Nor Suhada Anuar ◽  
Nor Mustaiqazah Juri ◽  
Anizah Rahumatullah ◽  
...  
Keyword(s):  
Small Sample Size ◽  
Rapid Test ◽  
High Specificity ◽  
Strongyloides Stercoralis ◽  
Cross Reactivity ◽  
Small Sample ◽  
Polystyrene Microspheres ◽  
Diagnostic Specificity ◽  
Serum Samples ◽  
Rapid Tests

A lateral flow rapid test for strongyloidiasis will greatly facilitate the control and elimination of the disease. Previously SsRapid™ prototype rapid test showed high diagnostic specificity to detect Strongyloides infection, determined using non-Strongyloides sera negative by IgG-ELISAs. Since high specificity is crucial before a test is used for public health control activities, further validation of its specificity is needed. Also, it needs to be ascertained whether non-Strongyloides sera positive by IgG-ELISAs and SsRapid are truly positive for Strongyloides or are cases of cross-reactivity. We performed 84 rapid tests (two types of dipsticks and cassettes) using 34 serum samples. They were divided into four groups based on Strongyloides infection and coinfection with other parasites and the availability of recombinant proteins and rapid tests for the latter. Sera was adsorbed using polystyrene microspheres beads separately coated with four recombinant parasite proteins. The small sample size is a limitation of this study; however, the overall results showed that the sera adsorption procedure was successful, and the SsRapid test is specific.

scholarly journals Epidemiological Study of Thogoto and Dhori Virus Infection in People Bitten by Ticks, and in Sheep, in an Area of Northern Spain

2020 ◽  
Vol 17 (7) ◽  
pp. 2254
Author(s):  
Lourdes Lledó ◽  
Consuelo Giménez-Pardo ◽  
María Isabel Gegúndez
Keyword(s):  
Virus Infection ◽  
Epidemiological Study ◽  
Human Subjects ◽  
Acute Infection ◽  
Immunofluorescence Assay ◽  
Northern Spain ◽  
Serum Samples ◽  
Igm Antibodies

There is little information on Thogoto virus (THOV) and Dhori virus (DHOV)infection in Spain. A total of 283 serum samples from 150 human subjects (78 males, 72 females) bitten by ticks, as well as samples from 120 sheep (one per animal), were studied by immunofluorescence assay. All human and animal subjects were from the province of Palencia in northern Spain. Eight human subjects had antibodies against THOV (seroprevalence: 5.3%) and six had antibodies against DHOV (seroprevalence: 4%); titers ranged between 1/32–1/256 and 1/32–1/128, respectively. No significant differences were seen in seroprevalence in terms of gender or age, although people with antibodies were significantly more likely to have had contact with livestock for professional reasons. One subject with an acute infection had IgM antibodies to both viruses and seroconverted to IgG. For the sheep, 24 serum samples were positive for antibodies to THOV (seroprevalence: 20%) and 32 for antibodies to DHOV (seroprevalence: 26.8%); titers ranged between 1/16 and 1/128. The seroprevalence of both viruses was significantly higher in animals < 4 years of age. Together, these results reveal the circulation of DHOV and THOV in humans and sheep in the province of Palencia. Sheep might be used as indicators of the presence of these organisms.

scholarly journals Lateral Flow Rapid Test for Accurate and Early Diagnosis of Scrub Typhus: A Febrile Illness of Historically Military Importance in the Pacific Rim

2017 ◽  
Vol 182 (S1) ◽  
pp. 369-375 ◽  
Author(s):  
Chien-Chung Chao ◽  
Zhiwen Zhangm ◽  
Giulia Weissenberger ◽  
Hua-Wei Chen ◽  
Wei-Mei Ching
Keyword(s):  
Early Diagnosis ◽  
Scrub Typhus ◽  
Rapid Test ◽  
Febrile Illness ◽  
Lateral Flow ◽  
Pacific Rim ◽  
The Pacific

scholarly journals Evaluation of an Immunoglobulin M Capture Enzyme-Linked Immunosorbent Assay for Diagnosis of Orientia tsutsugamushi Infection

2003 ◽  
Vol 10 (3) ◽  
pp. 394-398 ◽  
Author(s):  
Won-Jong Jang ◽  
Myung-Suk Huh ◽  
Kyung-Hee Park ◽  
Myung-Sik Choi ◽  
Ik-Sang Kim
Keyword(s):  
Immunosorbent Assay ◽  
Scrub Typhus ◽  
Microtiter Plate ◽  
Immunoglobulin M ◽  
Enzyme Linked Immunosorbent Assay ◽  
Orientia Tsutsugamushi ◽  
Serum Samples ◽  
Capture Elisa ◽  
Igm Antibodies ◽  
Immunodominant Antigen

ABSTRACT To differentiate scrub typhus from other acute febrile diseases, a rapid and reliable serological diagnosis is important. We developed an immunoglobulin M (IgM) capture enzyme-linked immunosorbent assay (ELISA) for diagnosis of recent Orientia tsutsugamushi infections in humans. The 56-kDa major outer membrane protein of O. tsutsugamushi is well known as the most immunodominant antigen in scrub typhus. The test is based on the use of the biotinylated recombinant 56-kDa protein of O. tsutsugamushi Boryong, Bor56, which was expressed as a fusion protein with a maltose-binding protein in Escherichia coli. In the test, the serum IgM antibodies were captured by anti-human IgM antibodies coated onto a microtiter plate. The captured IgM antibodies were revealed through sequential addition of biotinylated Bor56 antigen and peroxidase-conjugated streptavidin to the plate. The IgM capture ELISA was compared with the immunofluorescence antibody assay (IFA) by testing 176 serum samples from patients with diagnosed cases of rickettsial disease and patients with other acute febrile diseases. Of the 81 IgG IFA-positive samples, 78 tested positive (sensitivity, 96.3%) and all 31 IgM IFA-positive samples tested positive (sensitivity, 100%) by the IgM capture ELISA. The specificity of the IgM capture ELISA was 99%, and 1 of the 95 IFA-negative samples was positive in the assay. These results strongly suggest that IgM capture ELISA using the recombinant Bor56 antigen is a reliable and detailed method for the detection of early O. tsutsugamushi infection.

scholarly journals Diagnostic Accuracy of the InBios Scrub Typhus Detect Enzyme-Linked Immunoassay for the Detection of IgM Antibodies in Northern Thailand

2015 ◽  
Vol 23 (2) ◽  
pp. 148-154 ◽  
Author(s):  
Stuart D. Blacksell ◽  
Ampai Tanganuchitcharnchai ◽  
Pruksa Nawtaisong ◽  
Pacharee Kantipong ◽  
Achara Laongnualpanich ◽  
...  
Keyword(s):  
Diagnostic Accuracy ◽  
False Positive ◽  
Gold Standard ◽  
Latent Class ◽  
Scrub Typhus ◽  
Febrile Illness ◽  
Statistical Correlation ◽  
Immunofluorescence Assay ◽  
Enzyme Linked Immunosorbent Assay ◽  
Northern Thailand

ABSTRACTIn this study, we examined the diagnostic accuracy of the InBios Scrub Typhus Detect IgM enzyme-linked immunosorbent assay (ELISA) and determined the optimal diagnostic optical density (OD) cutoffs for screening and diagnostic applications based on prospectively collected, characterized samples from undifferentiated febrile illness patients in northern Thailand. Direct comparisons with the serological gold standard, indirect immunofluorescence assay (IFA), revealed strong statistical correlation of ELISA OD values and IFA IgM titers. Determination of the optimal ELISA cutoff for seroepidemiology or screening purposes compared to the corresponding IFA reciprocal titer of 400 as previously described for Thailand was 0.60 OD, which corresponded to a sensitivity (Sn) of 84% and a specificity (Sp) of 98%. The diagnostic performance against the improved and more-stringent scrub typhus infection criteria (STIC), correcting for low false-positive IFA titers, resulted in an Sn of 93% and an Sp of 91% at an ELISA cutoff of 0.5 OD. This diagnostic ELISA cutoff corresponds to IFA reciprocal titers of 1,600 to 3,200, which greatly reduces the false-positive rates associated with low-positive IFA titers. These data are in congruence with the recently improved serodiagnostic positivity criteria using the Bayesian latent class modeling approach. In summary, the InBios Scrub Typhus Detect IgM ELISA is affordable and easy-to-use, with adequate diagnostic accuracy for screening and diagnostic purposes, and should be considered an improved alternative to the gold standard IFA for acute diagnosis. For broader application, regional cutoff validation and antigenic composition for consistent diagnostic accuracy should be considered.

scholarly journals Detection and Molecular Characterization of Orientia tsutsugamushi from Suspected Scrub Typhus Patients in Mizoram, India

2021 ◽  
Vol 10 (10) ◽  
pp. 514-523
Author(s):  
Vanramliana Gabriel Rosangkima ◽  
Lalnunnemi Ralte Lalremruata ◽  
Christine Vanlalbiakdiki Sailo Hunropuia ◽  
Deborah Lalnghakmawii Lalfakzuala Pautu
Keyword(s):  
Nested Pcr ◽  
Scrub Typhus ◽  
Specific Antigen ◽  
Serum Samples ◽  
Antigen Gene ◽  
Molecular Tests ◽  
Related Genotype ◽  
High Degree ◽  
Higher Sensitivity

Serologic and molecular tests were performed for the diagnosis and to detect O. tsutsugamushi genotypes that are circulating in the state of Mizoram, India. Blood samples from scrub typhus-suspected patients were collected from Synod Hospital, Durtlang, Mizoram. Weil-Felix and immunochromatographic test (ICT) were performed from the serum samples. Nested PCR (nPCR) amplification of 47kDa outer membrane protein antigen gene and 56kDa type-specific antigen gene were done from the whole blood. 141/177 (79.66%) and 134/177 (75.7%) cases showed the presence of antibody against scrub typhus by Weil-Felix and ICT assays respectively. 76/177 (42.93%) patients showed the presence of 47kDa OMP antigen gene by nPCR while 55/177 (31.07%) showed the presence of 56kDa TSA gene by nPCR. Phylogenetic analysis of 56kDa TSA gene sequence revealed that Karp-related genotype was the most common genotype in the study area followed by Kato-related genotype. In this study, a high degree of diversity of O. tsutsugamushi was observed similar to the observations reported from other parts of India. Nested PCR of 47kDa OMP antigen gene showed higher sensitivity as compared to nPCR amplification of 56kDa TSA gene suggesting it as the assay of choice for diagnosis of scrub typhus disease.

scholarly journals Utility of rapid diagnostic kit tests for diagnosis of suspected dengue fever

2019 ◽  
Vol 7 (5) ◽  
pp. 1670
Author(s):  
Sarita Otta ◽  
Bichitrananda Swain
Keyword(s):  
Platelet Count ◽  
Dengue Fever ◽  
Rapid Test ◽  
Febrile Illness ◽  
Serum Samples ◽  
Serological Tests ◽  
Ns1 Antigen ◽  
Elisa Technique ◽  
Low Platelet Count ◽  
Sensitivity Specificity

Background: Dengue fever often presents as an undifferentiated febrile illness requiring a laboratory test for identification. Serological tests particularly on rapid kits for the detection of NS1Antigen, IgG and IgM antibodies are the most commonly performed test across the country.Methods: The serum samples of suspected dengue cases were tested by Rapid test kits for assessing all the three parameters as well as by ELISA for NS1 antigen test. The platelet count of the patients was obtained from automated coulter counter. The results thus obtained were analyzed in Excel format.Results: The serum samples from 304 suspected Dengue fever cases were received in the lab, of which 190 samples were positive either by rapid or ELISA and 176 when rapid card test was considered alone Highest seropositivity of dengue cases were observed in the age group of ≥60 years (79.2%) followed by 45-59 years (70.7%). On rapid test, 78 cases were NS1 antigen positive of which 60 cases were positive only for NS1 antigen. When NS1 rapid and ELISA tests when compared, 16 kit negative tests were positive on ELISA while 34 kit positive tests were ELISA negative.  Sensitivity, specificity, PPV and NPV when only NS1 was considered on rapid test kits when compared with ELISA were 78.9%, 87.8%, 63.8% and 93.8%. 33.5% of serologically positive cases of Dengue had low platelet count on admission while only among negative cases 17.2% had a low platelet.Conclusions: Rapid kits often show variable results thus needing a validation of them from end user. As a positive dengue test result is an essential prerequisite for diagnosis thus it is essential that for serological tests ELISA technique should be used for reporting. Thus, it also mandates more efforts at decentralization of NVBDCP to include both government and non government institutions.

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