Finding the right tests…
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Finding the right tests…
Serology
TYPHOID IGM checks your blood for one class of antibody your immune system makes early in a typhoid infection, caused by bacteria called Salmonella Typhi. Because IgM tends to appear before IgG, a positive result on this test alone is generally read as a sign of a recent or current infection rather than an old one. Antibody tests like this are used alongside, not instead of, a blood culture, which stays the more definitive way to confirm typhoid — health guidance notes antibody-based tests, including the older Widal test, can give false positives and don't always separate a genuine current infection from past exposure. Your doctor is likely to order this alongside a blood culture rather than on its own.
A positive or negative reading is what comes back from this test, showing whether IgM antibodies against Salmonella Typhi are currently in your blood. IgM is generally the first antibody your body produces once typhoid infection sets in, so it's more useful for identifying a current or recent infection than IgG is on its own. It's typically ordered alongside a blood culture and complete blood count, since serologic tests including antibody assays aren't considered reliable enough on their own to confirm typhoid. A single blood sample is enough, with no special preparation needed.
Typhoid fever is caused by Salmonella Typhi bacteria, and your immune system responds by producing antibodies against it, starting with IgM. This is the antibody class this test looks for, and it typically shows up before IgG does, which is why a positive IgM alone leans toward reading the infection as current or recent.
Even though an IgM result comes back faster than a culture, it isn't considered definitive on its own. Public health guidance describes serologic tests for typhoid, including the well-known Widal test, as unreliable because of a high rate of false positives, and notes they can't clearly distinguish an active infection from a past one or from vaccination. Blood culture, which grows the actual bacteria from your blood, remains the test doctors rely on most to confirm the diagnosis, even though it can take several days for a result.
Because of these limits, this IgM test is usually one part of a wider workup — alongside a blood culture, a complete blood count showing signs of infection, and your symptoms and travel or exposure history — rather than the single deciding result.
It's generally read as a sign of a current or recent infection, since IgM tends to appear early. Your doctor will usually confirm this alongside a blood culture.
Blood culture remains the more definitive way to confirm typhoid, since antibody tests, including IgM, can occasionally give a false positive and aren't considered reliable enough alone.
IgM tends to appear first and points toward a current or recent infection, while IgG appears later and can persist for years, making it harder to use alone for timing an infection.
No. The Widal test measures a different type of antibody response and has a high rate of false positives; health guidance no longer recommends relying on it, favouring more specific antibody or culture-based tests instead.
This page is general information about the test, not medical advice. Your own report's reference ranges apply — please discuss your results with your doctor.
IgM-based rapid tests can turn positive within a few days of infection, though exact timing varies between people and test methods.
No. No special preparation, including fasting, is needed before this blood draw.
Antibody-based typhoid tests, including IgM assays, can occasionally give a false positive, which is one reason your doctor pairs this result with a blood culture and your symptoms rather than relying on it alone.