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Typhidot

Bacterial infections Biomarker

Sample Needed

Collection Type: Blood

Body System

Related System: Bacterial infections

Overview

Typhidot is a rapid serologic test that detects IgM and IgG antibodies directed against a specific outer membrane (50 kDa) antigen of Salmonella enterica serovar Typhi. The test is used to support a presumptive diagnosis of typhoid (enteric) fever by identifying recent (IgM) or past/established (IgG) immune responses. It is ordered when patients present with persistent fever, headache, abdominal pain, constipation or diarrhea, and sometimes rose spots or hepatosplenomegaly. Results can vary with timing of illness (antibodies may not be detectable very early), prior vaccination or past infection (IgG), age (young children and elderly may show weaker antibody responses), and immune status (immunosuppressed patients may have blunted responses).

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Test Preparation

No special preparation is required

Why Do I Need This Test

Profile: Bacterial infections (typhoid/enteric fever workup).
Symptoms prompting test: sustained fever, abdominal symptoms, headache, malaise, possible rash or hepatosplenomegaly.
Diagnoses/monitoring: suggests acute or recent S.
Typhi infection; helps clinical decisions while awaiting cultures.
Reasons for abnormal results: recent infection (IgM), prior exposure or vaccination (IgG), cross-reactive infections, or technical/early-sampling issues.
Biological meaning: IgM = recent/acute response; IgG = established or past response.
Lifestyle/family history: recent travel to endemic areas, exposure to contaminated food/water, household contact with typhoid case.

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Understanding Test Results

IgM negative IgG negative: no detectable antibody response; may indicate no infection or testing too early.
Repeat testing or blood culture recommended if clinical suspicion persists.
IgM positive (with or without IgG): indicates recent or acute infection (antibodies commonly appear ~3–7 days after symptom onset); supports presumptive diagnosis and often prompts empiric therapy and confirmatory culture.
IgG positive alone: suggests past infection, later stage of illness, or prior vaccination; less specific for active disease.
Both IgM and IgG positive: consistent with ongoing or recent infection transitioning to convalescence.
Interpretation must consider timing, vaccination history, possible cross-reactivity (other Salmonella or infectious agents), prior antibiotic use (may reduce culture yield), and host immune status; positive Typhidot should be correlated with clinical findings and confirmed by blood culture where possible.

Normal Range

Negative for IgM and IgG (no antibodies detected) qualitative

FAQs

Q: What if Typhidot is positive?

A: A positive Typhidot suggests recent or current Salmonella Typhi infection: IgM indicates acute/recent infection, IgG indicates past exposure or later stage. Correlate with symptoms and confirm with blood culture, antibiotic sensitivity testing, and clinical assessment. Begin appropriate antibiotic treatment as advised, ensure hydration, and monitor for complications. False positives and vaccine-related cross‑reactivity can occur, so consult your doctor.

Q: What is the difference between typhoid and Typhidot?

A: Typhoid is a systemic infection caused by Salmonella Typhi that produces high fever, abdominal pain, headache and possible complications; diagnosis relies on culture or clinical assessment. Typhidot is a rapid serologic blood test that detects IgM/IgG antibodies to S. Typhi for early diagnosis; it detects immune response, not the organism, and has variable sensitivity and specificity compared with culture.

Q: Which test confirms typhoid?

A: Blood culture is the primary confirmatory test for typhoid fever, especially in the first week of illness. Bone marrow culture is the most sensitive and can remain positive after antibiotics. Stool and urine cultures may detect Salmonella Typhi later. Serologic tests (Widal) and molecular (PCR) assays can support diagnosis but have limitations in sensitivity and specificity.

Q: What is a normal Typhidot level?

A: Normal Typhidot result is a negative (non‑reactive) test—no detectable IgM or IgG antibodies to Salmonella typhi outer membrane proteins. Positive IgM suggests recent/acute infection; IgG positivity indicates past exposure or later-phase response. Rapid-test results should be interpreted with clinical findings and confirmed by blood culture, since false positives and negatives can occur.

Q: Is typhoid serious?

A: Yes typhoid can be serious. Caused by Salmonella Typhi, it produces high fever, abdominal pain, diarrhea or constipation and can lead to severe complications like intestinal bleeding or perforation, septic shock and death if untreated. Prompt diagnosis and antibiotic treatment plus fluids usually lead to recovery, but delayed care raises risk. Vaccination, safe water and hygiene prevent infection.

Q: What is the best cure for typhoid?

A: Typhoid is treated with appropriate antibiotics chosen by the clinician based on local resistance patterns and culture/susceptibility (common choices include ceftriaxone or azithromycin where fluoroquinolone resistance exists). Supportive care—hydration, fever control, nutrition—and close monitoring or hospitalization for severe cases are essential. Complete the full antibiotic course to prevent relapse and complications; vaccination and safe food/water reduce risk.