Fact-checked by Grok 2 weeks ago

Typhidot

Typhidot is a rapid immunochromatographic diagnostic test designed for the detection of IgM and IgG antibodies specific to Salmonella enterica serovar Typhi, the causative agent of typhoid fever, in human serum, plasma, or whole blood samples.^[1] It employs a dot-enzyme-linked immunosorbent assay (dot-ELISA) format that targets a 50 kDa outer membrane protein (OMP) antigen of the bacterium, allowing for differentiation between acute (IgM-positive) and past or chronic (IgG-positive) infections through visible colored dots on a test strip, with results interpretable within 15-30 minutes without specialized equipment.^[2]^[3] Developed as an accessible alternative to traditional methods like blood culture—the gold standard for typhoid diagnosis, which requires laboratory facilities and takes 2-5 days—Typhidot has gained widespread use in resource-limited, endemic regions such as South Asia and sub-Saharan Africa due to its simplicity, low cost (approximately $1-2 per test), and no need for refrigeration or trained personnel.^[4]^[5] However, its diagnostic performance varies across studies and settings; a Cochrane systematic review of multiple Typhidot variants reported pooled sensitivity of 84% (95% CI: 73%-91%) and specificity of 79% (95% CI: 70%-87%), though lower values (e.g., 27% sensitivity and 62% specificity) have been observed in some field evaluations, often due to cross-reactivity with other febrile illnesses like dengue or malaria.^[6]^[2] Compared to the Widal agglutination test, which has even poorer reliability (sensitivity 57%-74%, specificity 43%-83%), Typhidot offers improved speed but is not recommended as a standalone diagnostic by bodies like the World Health Organization, which advocates combining it with clinical history and confirmatory cultures for accurate management of suspected cases.^[7]

Background

Definition and Purpose

Typhidot is an immunochromatographic rapid diagnostic test (RDT) designed for the qualitative detection and differentiation of IgM and IgG antibodies against Salmonella enterica serovar Typhi (S. Typhi), the causative agent of typhoid fever.^[2] This immunoassay targets specific outer membrane proteins of S. Typhi, enabling serological identification of the infection through antibody responses.^[6] The primary purpose of Typhidot is to facilitate early diagnosis of acute typhoid fever in clinical settings, particularly in resource-limited endemic regions where access to blood culture—the gold standard for definitive diagnosis—is often unavailable due to infrastructure constraints.^[8] By detecting IgM (indicative of recent infection) and IgG (suggesting past or ongoing exposure), the test helps distinguish current acute cases from prior infections, allowing for timely initiation of antibiotic therapy to reduce complications and transmission.^[2] This is especially critical in areas with high typhoid burden, such as South Asia and sub-Saharan Africa, where the disease affects an estimated 9 million people annually (2019 estimates; recent data indicate around 8-9 million as of 2023).^[9]^[10] A variant, Typhidot-M, focuses exclusively on IgM detection to enhance specificity for acute-phase infections.^[11]

History and Development

The development of the Typhidot test originated in the late 1980s at the Institute for Research in Molecular Medicine, Universiti Sains Malaysia (USM), where researchers began investigating improved serological diagnostics for typhoid fever to address limitations in existing methods like the Widal test.^[12] In 1991, a key breakthrough occurred with the identification of a 50 kDa outer membrane protein (OMP) specific to Salmonella Typhi, which became the target antigen for enhancing specificity; this discovery was led by Dr. Asma Ismail, Dr. Ong Kok Hai, and Dr. Zainoodin Sheikh A. Kader.^[13] Building on this, the dot-enzyme immunoassay (dot-EIA) format was refined to detect IgM and IgG antibodies against the OMP, with initial evaluations conducted in endemic Malaysian populations. The first formal description and validation of the Typhidot test appeared in 1994, through a prospective study at Hospital Universiti Sains Malaysia that compared the dot-EIA to blood culture and Widal testing in 109 febrile patients, demonstrating high sensitivity (95%) and specificity comparable to the Widal test.^[14] That same year, Malaysian Biodiagnostic Research Sdn. Bhd. (MBDR) was established in collaboration with the Malaysian Technology Development Corporation to commercialize the technology, leading to the global launch of the Typhidot kit, which provided results in approximately 3 hours.^[12] Subsequent validation studies in the mid-1990s, including retrospective analyses in Kelantan and Kuala Lumpur, confirmed its utility in endemic settings, with ongoing refinements to improve performance in acute cases.^[15] To address cross-reactivity from IgG in chronic or past infections, the Typhidot-M variant was introduced in the late 1990s, incorporating an IgG depletion step to focus on IgM detection for earlier acute-phase diagnosis; this was evaluated in comparative studies showing improved accuracy in pediatric populations.^[11] Typhidot has been approved for use by the Malaysian Ministry of Health in clinical and surveillance settings, particularly in typhoid-endemic regions like Kelantan. In the 2010s, the World Health Organization evaluated Typhidot in systematic reviews for its potential in typhoid surveillance, noting its role as an adjunct tool despite not being endorsed as a standalone diagnostic due to variable performance across settings. MBDR transitioned to Reszon Diagnostics International around 2010, continuing production and distribution.^[16]^[17]

Scientific Basis

Principle of Operation

The Typhidot test operates on the principle of an indirect solid-phase immunochromatographic assay, utilizing lateral flow technology akin to rapid diagnostic tests for other infections, where patient serum or plasma migrates along a nitrocellulose membrane strip through capillary action.^[18] This format enables point-of-care detection without laboratory instrumentation, as the sample flows from a sample pad through a conjugate pad to the membrane, interacting with immobilized reagents to produce visible results.^[19] In the detection mechanism, the test targets antibodies against an outer membrane protein (OMP) of Salmonella enterica serovar Typhi, with the 50 kDa OMP antigen specifically immobilized on distinct test lines on the nitrocellulose membrane. Patient IgM or IgG antibodies present in the sample bind to colloidal gold-conjugated mouse anti-human IgM or IgG in the conjugate pad, forming immune complexes that migrate to the test zones; these complexes are then captured by the immobilized OMP antigens, resulting in the accumulation of gold particles and the formation of visible pink-purplish lines.^[18]^[19] A separate control line, coated with rabbit anti-mouse IgG antibodies, captures unbound gold conjugates to confirm proper test function, ensuring the absence of invalid results due to migration failure.^[2]^[20] The reaction stages begin with the addition of the sample to the pad, prompting immediate complex formation between patient antibodies and the gold-labeled anti-human immunoglobulins. The resulting complexes then migrate via capillary action across the membrane to the capture zones, where binding to the fixed OMP antigens halts further movement and amplifies the signal through gold particle aggregation, yielding detectable colored bands within 15-20 minutes.^[19] This process relies on the specific affinity of IgM and IgG for the OMP, enabling differentiation without enzymatic amplification.^[18] IgM detection signals an acute infection phase, as these antibodies typically appear within 2-3 days of symptom onset due to the early immune response. In contrast, IgG detection indicates convalescence or prior exposure, with levels peaking around 7-10 days post-infection and persisting longer for immune memory.^[2]

Antigens and Antibodies Detected

The Typhidot assay targets a specific 50 kDa outer membrane protein (OMP) derived from Salmonella enterica serovar Typhi, which serves as the primary antigen for antibody detection.^[21] This OMP, a homolog of the Escherichia coli TolC protein, forms a trimeric channel structure that facilitates molecular transport across the bacterial membrane, contributing to pathogen survival during infection.^[22] The antigen is produced recombinantly to ensure purity and consistency, enhancing its suitability for serological diagnostics by minimizing contaminants that could lead to non-specific binding.^[23] The test detects two classes of antibodies against this OMP: IgM and IgG. IgM antibodies, which are pentameric and represent the initial acute-phase humoral response, appear early in infection (typically within 2-3 days) and indicate active or recent typhoid fever; they are captured on a dedicated test line coated with anti-human IgM.^[20]^[2] IgG antibodies, monomeric in structure, emerge later (around 7-10 days) as part of the secondary immune response, conferring long-term immunity and persisting for months or years post-infection; these are detected on a separate test line using anti-human IgG.^[20] A control line, incorporating anti-immunoglobulin antibodies (such as rabbit anti-mouse IgG), binds conjugated detection reagents to validate assay performance and ensure proper sample migration, regardless of antibody presence.^[20] Biologically, the 50 kDa OMP elicits a robust humoral immune response during S. Typhi bacteremia due to its surface exposure and role in bacterial virulence, prompting rapid IgM production followed by IgG class switching.^[21] The assay's design is optimized to detect low antibody titers in early infection stages, with the recombinant antigen's high immunogenicity allowing sensitive identification of seroconversion.^[22] For specificity, the OMP is selectively reactive with typhoid patient sera and shows minimal cross-reactivity with antibodies from other Enterobacteriaceae infections, outperforming older assays that relied on whole-cell lysates prone to false positives from shared epitopes like lipopolysaccharides.^[21] This targeted approach reduces interference from common gut flora, improving diagnostic reliability in endemic areas.^[24]

Test Procedure

Sample Requirements

The Typhidot test utilizes biological samples to detect IgM and IgG antibodies indicative of Salmonella typhi infection, with preferences varying by kit version for optimal reliability. Procedures may vary by kit version; this describes the rapid immunochromatographic format.^[18] In point-of-care applications using compatible kits, whole blood collected via finger-prick may be used, requiring approximately 30-50 µL to facilitate rapid, minimally invasive testing using lancets and basic collection devices.^[2] For laboratory-based analysis, serum or plasma samples of 45 µL are standard, obtained through venipuncture into EDTA tubes for plasma or plain tubes for serum separation. No special anticoagulants beyond conventional EDTA are needed, ensuring compatibility with routine phlebotomy practices.^[20] Sample collection must follow aseptic protocols to prevent hemolysis, contamination, or turbidity, which could compromise antibody detection; grossly lipemic or hemolyzed specimens should be discarded and recollected. Whole blood or separated serum/plasma should be processed promptly, with centrifugation for plasma if not tested immediately. Samples should be tested promptly after collection; if delayed, refrigeration at 2-8°C extends usability for up to 3 days, while freezing at -20°C or below is advised for longer-term storage.^[20]^[25] The test accommodates patients across all age groups, including children and infants, with no fasting or special preparation required prior to sampling. Testing is most effective 3-7 days after symptom onset, aligning with the early serum phase when antibodies begin to appear reliably. All specimens must be handled as potentially infectious, with proper disposal of materials per biosafety guidelines.^[26]^[2]

Step-by-Step Protocol

The Typhidot test is performed using a lateral flow immunoassay kit designed for point-of-care settings, requiring minimal equipment and trained personnel.^[20]

Preparation

Assemble the necessary kit components, including the test strip (or cassette), diluent buffer (or chase buffer), and lancet for finger-prick sample collection if using whole blood. Ensure all components are at room temperature (15-30°C) prior to use, and prepare a clean, flat workspace to avoid contamination. The test strips are single-use and should be stored in their sealed pouches until immediately before testing; discard any damaged or expired materials.^[20]^[18]

Sample Application

For whole blood obtained via finger prick using the lancet, add 1 drop (approximately 30-50 μL) directly to the sample well of the test strip. For serum or plasma, add approximately 45 μL to the sample well. Immediately follow by adding 1 drop of the provided diluent buffer to the same well to initiate the reaction; gently tap the strip if needed to ensure even flow and avoid air bubbles.^[20]^[18]^[2]

Incubation and Timing

Place the test strip on a flat surface and allow the sample to migrate along the strip for 20 minutes to enable antibody-antigen binding and color development. Do not disturb the strip during this period, and read results at 20 minutes; results after 30 minutes may be invalid due to evaporation artifacts.^[20]^[18]

Quality Control

After the incubation period, visually inspect the strip for the appearance of the control line, which confirms proper test function and reagent performance. If the control line is absent or faint, the test is invalid—discard it and repeat with a new strip and fresh sample. All test strips are intended for single use to prevent cross-contamination, and used materials should be disposed of as biohazardous waste according to local regulations.^[20]^[18]

Interpretation of Results

Reading the Test Lines

The Typhidot test utilizes an immunochromatographic strip featuring three key visual indicators: the control line (C), the IgM-specific test line (T1), and the IgG-specific test line (T2). These lines form on a nitrocellulose membrane through the binding of patient antibodies to immobilized Salmonella typhi outer membrane protein antigens, leading to the accumulation of colloidal gold-conjugated reagents that produce visible pink or purplish-red bands.^[2] Test validity is determined by the presence of the control line, which appears as a distinct red or pink band to confirm adequate sample migration and reagent integrity; its absence indicates an invalid result due to potential issues with procedure or materials, requiring the test to be repeated with a fresh strip.^[20] The intensity of the test lines is assessed qualitatively, with any discernible colored band—from faint to strong—deemed positive for the respective antibody (IgM at T1 or IgG at T2), as the assay does not require quantification or grading beyond visibility.^[27] Common visual representations include diagrams showing a negative result with only the control line visible, contrasted against positive outcomes where the control line accompanies a band at T1 (IgM only), T2 (IgG only), or both (combined IgM and IgG), facilitating straightforward interpretation without specialized equipment.^[20]

Clinical Significance of Antibody Patterns

The Typhidot test interprets antibody patterns to distinguish stages of typhoid fever infection. A positive IgM result alone typically indicates an acute infection in the early phase, occurring within the first 7 days of symptom onset, reflecting the initial immune response to Salmonella Typhi.^[21] In contrast, an isolated positive IgG result suggests past exposure, vaccination, or late-stage infection, as IgG antibodies persist for months to years after resolution.^[21] The presence of both IgM and IgG antibodies signifies an active ongoing infection, often in the middle phase beyond the first week, indicating a more established humoral response.^[21] A negative result for both antibodies denotes no detectable infection, either due to absence of exposure or pre-seroconversion in very early cases.^[21] IgM antibodies rise first in the course of typhoid, becoming detectable as early as 2-3 days after fever onset, with overall sensitivity reaching up to 90% in acute cases, while IgG follows in the second week for monitoring immunity and long-term exposure.^[28] This temporal pattern aids in confirming outbreaks in endemic areas, where serial testing can track seroconversion rates among symptomatic populations.^[21] From a prognostic standpoint, an early positive IgM result signals the need for prompt antibiotic treatment to prevent complications, as it correlates with active bacterial replication in the early acute phase.^[28] Persistent IgG positivity without IgM, observed in convalescent patients, generally indicates recovery and low risk of relapse, supporting decisions on follow-up care.^[21] In endemic settings, combined IgM and IgG positives on Typhidot confirm 80-90% of culture-proven typhoid cases among symptomatic patients, providing reliable evidence for diagnosis when blood culture yields are limited by prior antibiotic use.^[28] For instance, in Malaysian children with febrile illness, the test identified acute infections with 90.3% sensitivity against culture-confirmed standards, highlighting its utility in resource-constrained environments.^[28]

Diagnostic Performance

Sensitivity and Specificity Metrics

The Typhidot test demonstrates variable diagnostic performance when evaluated against the gold standard of blood culture for typhoid fever confirmation. A 2017 Cochrane systematic review and meta-analysis reported pooled sensitivity of 84% (95% CI: 73%-91%) and specificity of 79% (95% CI: 70%-87%) across 22 studies evaluating different formulations of the test; in a subgroup of 13 studies where indeterminate results were reported or not applicable, sensitivity was 78% (95% CI: 65%-87%) and specificity 77% (95% CI: 66%-86%).^[18] For antibody-specific metrics, IgM detection shows sensitivity of 70%-92% in acute cases, with higher rates observed during early fever stages (days 3-5 of illness), reflecting its utility in identifying ongoing infection.^[29] In contrast, IgG sensitivity ranges from 60%-80% during the convalescent phase, indicating prior exposure but less reliability for acute diagnosis.^[30] Performance varies across studies due to regional differences and methodological factors. An early Malaysian validation study reported 90.3% sensitivity and 93.1% specificity.^[31] More recently, a 2024 cross-sectional study in southern Ghana among culture-positive cases found 34.5% sensitivity and 45.0% specificity, potentially attributable to low bacterial loads in samples.^[32] These metrics generally surpass those of the Widal test, which exhibits lower specificity (often <70%).^[18]

Factors Affecting Accuracy

Several biological and environmental factors influence the reliability of the Typhidot test by impacting antibody detection or causing misinterpretation of results. In the early phase of typhoid fever, particularly within the first 3 days of symptom onset, the test's sensitivity is low due to delayed seroconversion, as IgM antibodies against Salmonella typhi outer membrane protein typically emerge 2–3 days after infection begins.^[2] Cross-reactivity with other pathogens is a major source of false positives, especially in regions where multiple diseases co-circulate. The test can react with antibodies from non-typhoidal Salmonella infections (observed in up to 20% of cases), as well as dengue and malaria, leading to reduced specificity in co-endemic areas.^[33] Additionally, prior typhoid vaccination can elevate baseline IgG levels, mimicking current infection and contributing to false positives.^[34] Technical aspects related to test handling also affect accuracy. Improper storage of test kits at temperatures above 30°C can degrade the immobilized antigens, potentially lowering sensitivity, as the recommended storage range is 2–30°C to maintain reagent stability.^[35] User error in interpreting faint or ambiguous test lines may further lead to incorrect readings, particularly in resource-limited settings where training varies.^[36] Population-specific effects modulate the test's overall performance. Accuracy tends to be higher in adults than in children, with studies reporting lower sensitivity in pediatric populations (around 65–93%) due to differences in immune responses and disease presentation.^[37] In endemic versus non-endemic settings, baseline disease prevalence alters predictive values; higher prevalence in endemic areas improves positive predictive value but can exacerbate issues from cross-reactivity, while low prevalence in non-endemic regions reduces negative predictive value.^[38]

Clinical Applications

Role in Typhoid Diagnosis

Typhidot serves as an initial screening tool in primary care settings for patients presenting with fever lasting more than three days accompanied by abdominal symptoms suggestive of typhoid fever, such as pain or distension.^[2] In such cases, a positive Typhidot result prompts the initiation of empiric antibiotic therapy, such as azithromycin or ceftriaxone (considering local antimicrobial resistance patterns), to address the infection promptly while awaiting results from confirmatory tests like blood culture.^[39]^[40] This approach aligns with syndromic management strategies recommended by the World Health Organization for enteric fever in endemic regions, where clinical suspicion guides early intervention to prevent progression, though WHO prefers blood culture for confirmation and notes limitations of serological tests.^[9] As an adjunctive diagnostic, Typhidot complements the gold standard blood culture and molecular methods like PCR, which provide definitive identification of Salmonella Typhi but require laboratory infrastructure.^[7] It is particularly favored over the traditional Widal test in field and resource-limited environments due to its rapid turnaround time of approximately 15-20 minutes compared to the 48-72 hours needed for blood culture results.^[5] The test detects IgM and IgG antibodies against Salmonella Typhi antigens, with patterns indicating acute or past infection to inform clinical decisions.^[21] Typhidot is well-suited for use in outpatient clinics, travel medicine practices evaluating returned travelers from endemic areas, and public health surveillance programs in high-burden countries such as India and Pakistan, where typhoid incidence exceeds hundreds of cases per 100,000 population annually.^[41]00210-8/fulltext) In these contexts, it supports decentralized testing in line with WHO's emphasis on accessible diagnostics in resource-limited settings, though confirmatory testing is preferred.^[9]^[7] By providing results on the same day, Typhidot supports earlier treatment initiation than culture-based methods alone, which can reduce the risk of severe complications such as intestinal perforation or sepsis in untreated cases. Antibiotic selection should account for local AMR patterns, as extensively drug-resistant strains are increasingly common in regions like South Asia.^[42]^[9] This timely intervention is critical in endemic settings, where delays in diagnosis contribute to higher morbidity rates.^[43]

Advantages Over Traditional Tests

Typhidot offers rapid results within 15 to 20 minutes through its immunochromatographic format, enabling prompt diagnosis without the extended wait times associated with traditional tests. In contrast, the Widal test often involves observation periods of up to 2 hours for agglutination in tube methods, while blood culture requires 3 to 5 days of incubation for bacterial growth. This speed is particularly beneficial in acute settings where timely treatment initiation can improve patient outcomes.^[18]^[44]^[45] The test's detection of antibodies against the outer membrane protein (OMP) of Salmonella Typhi enhances specificity by minimizing cross-reactivity with non-typhoidal pathogens, such as Brucella species, which is a common issue with the Widal test's reliance on O and H antigens that yield specificities around 50-60% in endemic areas. Unlike the Widal test, Typhidot does not require demonstration of rising antibody titers through paired sera, allowing for immediate interpretation based on IgM and IgG presence. This OMP-based approach thus provides more reliable results in regions with high rates of cross-reacting infections.^[46]^[47]^[30] As a point-of-care test, Typhidot requires minimal laboratory infrastructure and can be performed by non-specialist healthcare workers, making it highly accessible in rural or resource-limited settings where traditional diagnostics like blood culture demand specialized equipment and trained personnel. Its cost-effectiveness, at approximately $2-5 per test, contrasts with blood culture's $10-20 expense plus ongoing equipment and reagent needs, broadening its utility in low-income areas.^[48]^[49]^[50] The visual readout of Typhidot's test lines reduces interpretation errors compared to the subjective agglutination assessment in Widal tests, enhancing user-friendliness for frontline providers. Additionally, the kit's stable shelf life of 12 months supports easy stockpiling and deployment during outbreaks, ensuring availability without frequent replacements.^[51]^[18]

Limitations and Considerations

Common Pitfalls and Cross-Reactivity

One common user error in interpreting Typhidot results involves misreading faint test lines as negative, particularly for IgM bands that may appear weakly due to low antibody titers early in infection; proper training is essential to distinguish valid positives from artifacts.^[2] Another frequent pitfall is performing the test too early, within 48 hours of symptom onset, which often yields false negatives because IgM antibodies typically become detectable only after 2-3 days of infection.^[2] Additionally, failing to verify the control line's validity can lead to overlooked invalid results, as the absence of a control band indicates test failure regardless of sample or reagent issues. Cross-reactivity can occur with closely related Salmonella serovars such as S. Paratyphi A and B due to shared O antigens, potentially leading to false positives.^[52] Similar interferences occur with scrub typhus (Orientia tsutsugamushi), where up to 5.8% of Typhidot-positive cases in endemic areas are attributable to this pathogen via non-specific antibody binding. Leptospirosis also triggers cross-reactivity, with approximately 21% (3/14 cases) of confirmed leptospiral infections yielding false-positive Typhidot IgM results owing to polyclonal B-cell activation and shared immunogenic structures.^[53] Vaccination with the live oral Ty21a typhoid vaccine, which uses attenuated S. Typhi, may induce antibodies that could cause positive Typhidot results, mimicking infection. Environmental factors such as high humidity can affect the stability of Typhidot strips, as with other nitrocellulose-based RDTs, potentially leading to invalid results if storage conditions exceed manufacturer specifications.^[54] Improper handling, such as contamination from unclean lancets or buffers, can increase invalid test rates in field settings, as seen in evaluations of similar lateral flow assays.^[55] To mitigate these issues, positive Typhidot results should always be confirmed with blood culture, the gold standard, to rule out cross-reactivity-driven misdiagnosis.^[2] In low-prevalence settings, where positive predictive value can fall below 50% due to elevated false-positive proportions, routine use of Typhidot is discouraged without epidemiological context.^[2]

Recommendations for Use

Rapid diagnostic tests such as Typhidot are sometimes used in resource-limited endemic settings for initial screening, but neither WHO nor CDC recommends them as standalone tools; blood culture remains the gold standard, and results should be interpreted with clinical context.^[18]^[56] However, it is not suitable for asymptomatic screening or detection of chronic carriers, as the test targets acute-phase antibodies rather than persistent bacterial shedding.^[57] In high-prevalence settings with compatible symptoms, a positive Typhidot result increases the likelihood of typhoid, but confirmatory testing is still required due to variable predictive values.^[6] Best practices for Typhidot application include testing 3-10 days after symptom onset, when IgM antibodies peak for early detection and IgG emerges for confirmation.^[2] For suspected paratyphoid infections, which Typhidot does not reliably detect due to its specificity for Salmonella Typhi antigens, results should be combined with stool culture to identify Salmonella Paratyphi.^[4] In cases of high clinical suspicion despite an initial negative result—such as persistent fever in an endemic setting—retesting after 2-3 days is advised to account for delayed seroconversion.^[58] In pediatric populations, including children under 5 years, Typhidot sensitivity may be reduced due to immature immune responses (overall pediatric sensitivity ~70-80% in some studies), necessitating correlation with other diagnostics like blood culture.^[59] For travelers returning from non-endemic areas, sole reliance on Typhidot should be avoided, as low disease prevalence can inflate false-positive rates and mislead management.^[56] Future directions emphasize integrating Typhidot with multiplex rapid diagnostic tests (RDTs) to differentiate typhoid from co-circulating illnesses like dengue in overlapping endemic regions, potentially improving syndromic management.^[60] As of 2025, recent evaluations affirm Typhidot's role in early diagnosis amid rising antibiotic resistance, though integration with molecular tests is being explored.^[4] Ongoing evaluations are also assessing its role in antibiotic resistance contexts, where accurate early diagnosis can guide targeted therapy and curb misuse of broad-spectrum agents.^[4]

References

[1]
Typhidot Test - Purpose, Results, Normal Range, and more
The Typhidot test is a diagnostic blood test used to detect antibodies against Salmonella typhi, the bacteria responsible for typhoid fever.
[2]
Typhidot - A blessing or a menace - PMC - NIH
Typhidot has been used as the only tool to diagnose typhoid fever by general practitioners and consultants despite its low sensitivity and specificity causing ...
[3]
Typhidot – Knowledge and References - Taylor & Francis
Typhidot is a serological assay that uses a dot ELISA test format to detect either IgG or IgM antibodies against a specific antigen (50 kDa) on the outer ...<|control11|><|separator|>
[4]
Diagnostic performance of Typhidot RDT in diagnosis of typhoid ...
Nov 7, 2024 · Generally, patients diagnosed with Typhidot test assay presented with acute non-malarial fever (or history of fever within the past 24 h) with ...
[5]
Typhoid Diagnostics
A definitive diagnosis of typhoid requires isolation of the Salmonella Typhi bacterium through blood culture. This method is considered the gold standard for ...
[6]
Rapid diagnostic tests for typhoid and paratyphoid (enteric) fever
May 25, 2017 · Across all forms of the Typhidot test, the average sensitivity was 84% (95% CI 73% to 91%) and specificity was 79% (95% CI 70% to 87%).
[7]
Diagnostics for Typhoid Fever: Current Perspectives and Future ...
Jun 2, 2023 · The Widal test is the most used test to diagnose typhoid despite a low performance (sensitivity range, 57%–74%; specificity range, 43%–83% [8]) ...<|control11|><|separator|>
[8]
A Comparative Evaluation of Different Diagnostic Modalities in the ...
Enteric Fever is caused by Salmonella enterica serotype Typhi and Salmonella ... Prospective evaluation of a rapid diagnostic test Typhidot for typhoid fever.Missing: origin | Show results with:origin
[9]
Typhoid Fever Surveillance, Incidence Estimates, and Progress ...
Feb 17, 2023 · An estimated 11–21 million typhoid fever cases and 148,000–161,000 associated deaths occurred in 2015. The World Health Organization (WHO) ...
[10]
Typhidot Test - Price, Normal Ranges, Report & Preparation
What is the Typhidot test? A typhidot test is done to detect IgM and IgG antibodies againstSalmonella typhi, the bacteria that causes typhoid fever.Missing: definition | Show results with:definition
[11]
[PDF] A Case Study Analysis of Typhidot: An Example of Market ... - Sciedu
Despite its early commercialization potential, the internal and external challenges faced by MBDR the commercial start-up company for Typhidot, were just ...
[12]
https://www.sciedupress.com/journal/index.php/ijfr/article/download/15639/9712
[13]
https://doi.org/10.1016/S0006-291X(05)81417-2
[14]
Retrospective review of dot enzyme immunoassay test for typhoid ...
Aug 6, 2025 · Typhidot (Malaysian Biodiagnostic Research SDN BHD, Kuala Lumpur, Malaysia), was developed for the detection of specific IgM and IgG against a ...Missing: Universiti Sains<|control11|><|separator|>
[15]
[PDF] typhoid carrier test (typhidot-c)
Typhidot-C is a typhoid carrier test used to detect carriers, who shed bacteria and are a reservoir for typhoid infection. Detection is necessary for control.Missing: history Universiti Sains
[16]
A Meta-Analysis of Typhoid Diagnostic Accuracy Studies
Of note: the current manufacturer of TyphiDot (Reszon Diagnostics International Sdn. Bhd., Selangor, Malaysia) has only been making this test since ca. 2010 ...
[17]
Rapid diagnostic tests for typhoid and paratyphoid (enteric) fever - NIH
May 25, 2017 · Typhidot®, Malaysian Bio‐Diagnostics Research, Selangor, Malaysia, Dot‐enzyme immunoassay. Detects IgG and IgM to 50 kdA S. Typhi Outer ...
[18]
Evaluation of Serological Diagnostic Tests for Typhoid Fever in ... - NIH
The TyphiDot assay is a dot enzyme immunoassay which detects serum anti-Salmonella IgM and IgG antibodies specific for a 50-kDa outer membrane protein (OMP) ...
[19]
New Advances in the Diagnosis of Typhoid and Detection of ... - PMC
An ideal diagnostic test for typhoid and typhoid carriers should be rapid, specific as well as sensitive. The development of a rapid and specific test combined ...
[20]
Structural and functional studies of a 50 kDa antigenic protein from ...
Aug 10, 2025 · ... An outer membrane protein (OMP) was demonstrated to be antigenic for S. typhi and subsequently developed into TYPHIDOT (Reszon Diagnostics ...
[21]
OMP for Salmonella typhi - Recombinant antigens - Rekom Biotech
OMP, a 50 kDa outer membrane protein, is key in the serological diagnosis of Salmonella typhi, the causative agent of multisystemic typhoid fever.Missing: Typhidot | Show results with:Typhidot
[22]
[PDF] TYPHIDOT Rapid IgG/IgM (Combo) Version2 (A rapid test for ...
PRINCIPLE OF THE TEST. The TYPHIDOT Rapid IgG/IgM (Combo) is an indirect solid-phase immunochromatographic assay. The specific S. typhi OMP antigen is.
[23]
Enteric fever and the diagnostic tools: defining the accuracy - Frontiers
Jan 28, 2024 · Generally, bone marrow culture/blood culture for the isolation of Salmonella typhi is a sensitive method and is suggested as the gold standard.Introduction · Materials and methods · Results · Discussion
[24]
Typhidot Test: Purpose, Procedures, Test Results and Normal Range
Oct 27, 2025 · The Typhidot test is used to detect antibodies (IgM and IgG) produced in response to a typhoid infection caused by Salmonella typhi. A typhoid ...
[25]
Typhidot Test: Purpose, Procedure & Results | Lal PathLabs Blogs
Apr 7, 2024 · Typhidot is a diagnostic test for typhoid to detect the presence of Salmonella typhi, a bacterium causing the fever. When the bacteria enter the ...
[26]
[PDF] Comparison of different test methods including polymerase chain ...
ii) Typhidot® test detects specific IgM and IgG antibodies to S. ... A nitrocellulose membrane strip containing two test bands (T1 and T2 bands) and a control.
[27]
Rapid and reliable serological diagnosis of enteric fever
The Typhidot test, which detects IgM and IgG antibodies to a Salmonella typhi-specific outer membrane protein, is as sensitive as, and more specific than, the ...
[28]
Prospective evaluation of a rapid diagnostic test Typhidot for typhoid ...
Typhidot test is rapid, easy to perform and reliable test for diagnosing typhoid fever, useful for small less equipped laboratories as well as for those ...
[29]
Sensitivity and specificity of typhoid fever rapid antibody tests for ...
TUBEX® and Typhidot® appeared to have comparable performance and were more specific although less sensitive than the semiquantitative slide agglutination test ...
[30]
Rapid and reliable serological diagnosis of enteric fever - PubMed
In order to increase diagnostic accuracy in an area of high endemicity, the Typhidot-M test has been developed in which IgG is first removed. This ...Missing: paper | Show results with:paper
[31]
Diagnostic performance of Typhidot RDT in diagnosis of typhoid ...
Nov 7, 2024 · Among the positive tests by culture, the Typhidot test detected 34.5% (n = 10) positives and 65.5% (n = 19) negatives. For culture negative ...Missing: layout | Show results with:layout
[32]
Sensitivity and specificity of typhoid fever rapid antibody tests for ...
Aug 9, 2025 · The tube agglutination test requires greater technical work and it takes 18-24 hours to get the results. So, in later years, Welch et al ...
[33]
Typhoid Test Results Explained: A Complete Patient Guide
Prior typhoid vaccination can cause elevated titers. What IgM and IgG Mean in TyphiDot Results. IgM antibodies are the first to appear in the bloodstream ...
[34]
https://www.mdrcindia.com/blog/detail/typhoid-test-results-explained-a-complete-patient-guide
[35]
Performance of Immunodiagnostic Tests for Typhoid Fever - MDPI
The present review aims to assess the specificity and sensitivity of the available literature on the immunodiagnostics of typhoid fever.Missing: history 1994
[36]
Sensitivity and specificity of Typhidot-M reported by various studies
[7][8][9][10] In a study comprising 105 children, Narayanappa et al., found out the sensitivity and specificity of Typhidot-M to be 92.6% and 37.5%, ...<|control11|><|separator|>
[37]
Comparative accuracy of typhoid diagnostic tools: A Bayesian latent ...
May 8, 2019 · ELISA IgM outperformed its IgG counterpart and the TPT test also performed very well with 94% sensitivity (76% to 100% in scenario analysis) and ...
[38]
Typhoid Fever Treatment & Management - Medscape Reference
Sep 4, 2025 · Hospitalized patients should be placed in contact isolation during the acute phase of the infection. Feces and urine must be disposed of safely.
[39]
Typhoid - World Health Organization (WHO)
Mar 30, 2023 · As of 2019 estimates, there are 9 million cases of typhoid fever annually, resulting in about 110 000 deaths per year. Typhoid risk is ...
[40]
Typhoid fever in India: A growing concern requiring ... - PMC - NIH
Feb 15, 2024 · According to one study, India recorded approximately 10 million cases of typhoid fever in 2021, making it the country with the highest burden of ...
[41]
Redefining typhoid diagnosis: what would an improved test need to ...
Oct 31, 2019 · To meet the needs of users in endemic regions, stakeholders proposed that an improved typhoid diagnostic test must be able to detect S.<|control11|><|separator|>
[42]
Assessment of Rapid Diagnostic Tests for Typhoid Diagnosis and ...
Typhidot Rapid (Reszon Diagnostic), Test-It™ (Life Assay Diagnostics). Assay and sample. Target, Salmonella typhi IgM anti-09 antibodies, IgM antibodies to a 50 ...Missing: Biodiagnostic | Show results with:Biodiagnostic
[43]
Widal Test- Principle, Procedure, Types, Results, Uses
Feb 5, 2022 · Positive test (presence of Salmonella antigen) = Agglutination within a minute · Negative test (absence of Salmonella antigen) = No agglutination ...
[44]
Typhoid Fever Workup - Medscape Reference
Sep 4, 2025 · In particular, stool culture may be positive for S typhi several days after ingestion of the bacteria secondary to inflammation of the ...Missing: Typhidot optimal
[45]
widal test / typhoid test (typhidot) Test - Portea Medical
Typhidot test is a dot ELISA kit that detects IgM and IgG antibodies against the outer membrane protein (OMP) of the Salmonella typhi.<|control11|><|separator|>
[46]
Evaluation of sensitivity and specificity of ELISA against Widal test ...
Nov 14, 2015 · Widal test, which has poor predictive outcomes in predominant typhoid population, is not standard enough to predict accurate diagnosis.Material And Methods · Quantitative Widal Test · Assessment Of Elisa For The...
[47]
Diagnostics for Typhoid Fever: Current Perspectives and Future ...
Jun 2, 2023 · These tests are cheap and simple, do not require sophisticated laboratories, and deliver results in a shorter time frame than blood culture, ...Missing: advantages simplicity
[48]
Comparison of Serological Test Kits for Diagnosis of Typhoid Fever ...
The cost in US dollars per test of the various kits sold in the Philippines in government tertiary hospitals was $4.90 for SD Bioline, TUBEX, and Mega and $6.86 ...
[49]
How Much Does a Blood Culture Cost Near Me? - MDsave
The cost of a Blood Culture ranges from $13 to $84. Those on high deductible health plans or without insurance can shop, compare prices and save.Missing: typhoid $10-20
[50]
Evaluation of Rapid Diagnostic Tests for Typhoid Fever
The TyphiDot is a DOT enzyme immunoassay that detects either IgM or IgG antibodies against a specific antigen on the outer membrane protein of serotype Typhi.
[51]
Comparative Evaluation of Various Tests for Diagnosis of ... - NIH
May 15, 2014 · Typhi and Paratyphi A was isolated in 17 (65.38 %) Typhidot M positive cases by culture of blood and stool specimens. Other workers like ...
[52]
[PDF] Reliability of Typhidot-M in diagnosis of typhoid fever in children
May 1, 2022 · The blood culture was considered negative when no growth was demonstrated after 10 days. All children were tested for. Widal on the 7th day of ...
[53]
Live Oral Typhoid Vaccine Ty21a Induces Cross-Reactive Humoral ...
Therefore, it was of importance to determine whether Ty21a immunization elicits IgA BM anti-LPS and anti-OMP responses that are cross-reactive among LPS and OMP ...Missing: Typhidot | Show results with:Typhidot
[54]
[PDF] Draft Target Product Profile for Acute Typhoid Fever Surveillance
Oct 23, 2024 · In addition, to understand the typhoid burden, the WHO recommends that countries conduct typhoid surveillance with a minimal surveillance ...
[55]
Addressing Barriers to the Development and Adoption of Rapid ...
... tests were never stored at temperatures greater than 30°C. This resulted in a test strip invalidity rate of only 10%, as compared with 17% for RDTs stored ...
[56]
Typhoid and Paratyphoid Fever | Yellow Book - CDC
Apr 23, 2025 · Typhoid and paratyphoid fever are acquired through consumption of water or food contaminated by feces of an acutely infected or convalescent ...<|control11|><|separator|>
[57]
Systematic Review of Rapid Typhoid Diagnostic Kits
The average sensitivity and specificity were approximately 80%–90% and 65%–78% for Typhidot, 85%–94% and 77%–89% for Typhidot-M, and 94.7% and 80.4% for Tubex.
[58]
Typhidot Test Report: Normal Range, Results Interpretation & What ...
Sep 9, 2025 · In simple words, the typhidot test is used to detect typhoid fever. It identifies IgM and IgG antibodies that the body produces when infected ...
[59]
diagnostic accuracy of typhidot test in pediatric patients presenting ...
Aug 7, 2025 · The sensitivity of typhidot was 72.46% and specifi city was 26.19%. The diagnostic accuracy was 54.95%. Conclusion: Overall specificity and ...<|separator|>