What this test measures
"Typhoid test" in Indian labs typically refers to a rapid card-based or ELISA test that detects IgM (and sometimes IgG) antibodies to Salmonella Typhi antigens — branded variously as Typhidot, Tubex, SD Bioline Typhoid IgG/IgM, etc. IgM positivity supports an acute or recent typhoid infection; IgG positivity reflects past exposure or convalescence.
It is important to know what these rapid tests are and what they are not. They are useful as point-of-care screens during a febrile illness, but they are not as specific or sensitive as a blood culture for Salmonella Typhi — which remains the gold-standard for typhoid diagnosis. Most Indian guidelines recommend ordering a blood culture alongside any rapid typhoid test, especially in the first week of fever.
Why it matters
Typhoid is endemic across India. Mumbai sees thousands of laboratory-confirmed cases each year, mostly during and after the monsoon, linked to contaminated water and food. Classical presentation is a stepladder fever rising over 5–7 days, headache, abdominal discomfort, relative bradycardia, hepatosplenomegaly, and rose spots. Untreated, typhoid can progress to intestinal perforation, sepsis, or death — early diagnosis is therefore important.
Antibiotic resistance in S. Typhi is a major and worsening problem in India. Extensively drug-resistant (XDR) typhoid strains have been documented; appropriate antibiotic choice (azithromycin, ceftriaxone, or carbapenems depending on susceptibility) and a blood culture to guide therapy are both important. Rapid antibody tests give a fast preliminary signal while culture is awaited.
How to prepare
No fasting required. Best taken 5–7 days after fever begins; earlier than that, antibodies may not yet be detectable. A blood culture is typically taken at the same time, ideally before any antibiotic is started.
Markers & reference ranges
Reference ranges below are typical adult values. Your lab's reported range may differ slightly based on the assay platform and patient demographics — always read your report against the range printed on it.
| Marker | Normal range | If low | If high |
|---|---|---|---|
| Salmonella Typhi IgM (—)[1] | Negative | — | Positive — supports current or recent typhoid infection. Confirm with blood culture and treat with the antibiotic recommended by local susceptibility data (commonly azithromycin or ceftriaxone in India). |
| Salmonella Typhi IgG (—)[1] | Negative | — | Positive — past typhoid exposure or vaccination, sometimes seen in convalescence. By itself, IgG positivity is not diagnostic of acute infection. |
Typhoid diagnostic tests compared
| Test | Best window | Sensitivity | Specificity |
|---|---|---|---|
| Blood culture (gold standard) | Week 1 | 40–80% (lower if antibiotic already started) | ~100% |
| Bone marrow culture | Week 1–3 | 80–95% | ~100% |
| Stool culture | Week 2+ | 30–70% | ~100% |
| Rapid IgM card / Tubex / Typhidot | Day 5+ | 60–80% | 70–90% |
| Widal (paired sample) | Week 2+ | Variable | Poor in endemic areas |
Frequently asked questions
When should the typhoid test be done?
Ideally 5 days or more after fever begins, when antibodies have had time to rise. A blood culture should be sent at the same time, before any antibiotic is started.
Is the rapid typhoid test as good as a blood culture?
No. Blood culture is the gold standard — it identifies the bacterium and tells the doctor which antibiotic will work. The rapid test gives a fast preliminary signal, but should not replace culture.
I had a typhoid vaccine — will my IgG be positive?
Possibly. The Vi-polysaccharide and Typbar-TCV vaccines can produce detectable IgG antibodies for many months. Mention any recent vaccination to your doctor — IgM rather than IgG is the marker of current infection.
How is typhoid different from a viral fever like dengue?
Typhoid usually has a stepladder fever rising over a week, abdominal symptoms, and relative bradycardia, while dengue presents with high fever, severe body ache, low platelets, and positive NS1. They overlap clinically, so blood tests for both are often ordered together.
How long does treatment take?
With the right antibiotic, fever usually settles in 4–7 days. The full course is 7–14 days. Carrier states (long-term excretion in stool) can develop in some patients and may need a longer course.
Can typhoid come back?
Yes — relapse occurs in around 5–10% of cases, usually 1–3 weeks after stopping antibiotics. A small fraction become chronic carriers. Follow-up cultures may be needed in food handlers.
How fast will I get the report?
The rapid card test result is available in 30 minutes; reports are delivered digitally within 1–2 hours by NABL-accredited labs in Mumbai and Thane. Blood culture results take 48–72 hours.
Related Infectious Disease tests
Tests commonly ordered alongside TYPHOID TEST, or that help interpret an unexpected result.
Sources & references
- NIH MedlinePlus — Typhoid Fever · accessed 2026-05-30T00:00:00.000Z
- WHO — Typhoid Fever Fact Sheet · accessed 2026-05-30T00:00:00.000Z
- NCBI StatPearls — Typhoid Fever · accessed 2026-05-30T00:00:00.000Z
- Indian Council of Medical Research (ICMR) — Antibiotic guidelines · accessed 2026-05-30T00:00:00.000Z
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