Overview: Salmonella Typhi IgG IgM Panel
Introduction: The Salmonella Typhi IgG IgM Panel is a diagnostic tool designed for typhoid fever screening using serum samples. In India, typhoid fever affects ~1 million cases/year (higher in rural/low-SES with poor sanitation/water), caused by Salmonella Typhi, presenting with prolonged fever, abdominal pain, and complications (intestinal perforation, encephalopathy). High morbidity from under-testing leading to delayed ceftriaxone/azithromycin, progression to carrier state or mortality. Per microbiology practices aligned with ICMR, National Centre for Disease Control, and IDSP guidelines, the test employs immunoassay for Salmonella Typhi IgG and IgM over 1â€"2 days with high accuracy, valuable for acute (IgM) vs past (IgG) infection diagnosis in endemic areas. This diagnostic falls under infectious disease screening and targets patients with prolonged fever or travel history, addressing accurate detection to guide antibiotics and public health measures. With elevated morbidity due to underdiagnosis, the test supports public health efforts by enabling rapid typhoid profiling and reducing transmission. Its serum-based approach ensures reliable IgG/IgM assessment.
Other Names: Typhidot Pnl.
FDA Status: FDA approved, CLIA certified for biochemistry/immunology, compliant with 2025 standards.
Historical Milestone: Typhidot IgG/IgM standard in typhoid endemic areas; in India, widely used in fever clinics.
Purpose: The test assesses 2 parameters including Salmonella Typhi IgG/IgM to guide typhoid fever screening, detect acute/past infection, inform antibiotics.
Test Parameters: 1. Salmonella Typhi IgG, 2. Salmonella Typhi IgM.
Pretest Condition: No fasting required; patients should have prolonged fever.
Specimen: 3 mL serum in 1 SST, transported within specified times to maintain sample viability.
Sample Stability at Room Temperature: 8 hours with proper handling to preserve antibody integrity, ensuring reliable test performance.
Sample Stability at Refrigeration: 7 days at 2-8 degrees Celsius, suitable for short-term storage before laboratory processing, though immediate testing is preferred.
Sample Stability at Frozen: 6 months at -20 degrees Celsius, allowing long-term storage for retesting, though freezing may affect some analytes.
Medical History: Patients should provide details on fever duration, travel, water source.
Consent: Written informed consent is required, detailing the test's purpose, potential risks of untreated typhoid including perforation, benefits of screening, and minimal discomfort from venipuncture.
Procedural Considerations: The test involves sample processing using immunoassay by trained personnel to ensure sterile technique, avoid hemolysis, and interpret results within 1â€"2 days using provided controls. Laboratories must maintain a controlled environment, adhere to quality assurance protocols.
Factors Affecting Result Accuracy: Delays beyond stability periods, improper storage conditions, hemolysis can affect results. Correlation with clinical evaluation or additional testing is recommended to confirm findings.
Clinical Significance: Positive IgM indicates acute typhoid, necessitating specialist input.
Specialist Consultation: Infectious disease specialists should be consulted for management.
Additional Supporting Tests: Blood culture, Widal for confirmation.
Test Limitations: Cross-reactivity possible; comprehensive approach required.
References: Indian Journal of Medical Microbiology 2024, Typhoid Studies India 2023.
