Finding the right tests…
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Finding the right tests…
Serology
LEPTOSPIRA IGM & IGG orders both leptospirosis antibody tests from one blood sample, giving your doctor an IgM and an IgG result together rather than requesting them one at a time. Because IgM tends to rise earlier in the illness and IgG later, reading both at once gives a rough sense of where in the course of infection you are, without needing to wait for a second visit to add the other. This combined test doesn't replace the confirmatory microscopic agglutination test used at reference laboratories, but it's a practical first step your doctor can order from a single draw of blood when leptospirosis is suspected after exposure to contaminated water, soil, or animal urine.
This test gives you two readings from one blood draw — Leptospira IgM and Leptospira IgG — both reported as positive or negative, plus how they relate to each other. Because IgM typically appears earlier in the illness and IgG later, having both results together helps your doctor judge roughly how far into the infection you might be. Neither result alone is fully confirmatory — a strongly reactive screening result is usually followed up with the microscopic agglutination test at a specialised laboratory. A single blood draw covers both tests, with no fasting required.
IgM and IgG rise on different timelines during a leptospirosis infection — IgM tends to appear first, while IgG generally takes longer to build up and lasts longer afterward. Testing for both from the same blood sample means your doctor doesn't have to choose one antibody type over the other or wait for a second appointment to check the one not ordered.
A positive IgM with a negative IgG generally points toward an earlier stage of infection, while a positive IgG, especially alongside a fading or negative IgM, can suggest the illness is further along or that the antibody response has had more time to develop. Neither pattern is a precise clock, since antibody timing varies between people and depends on how quickly each person's immune system responds.
This combined antibody test is a screening step, not the final word — health guidance treats the microscopic agglutination test, run at specialised reference laboratories, as the confirmatory standard, usually requiring a high single titre or a clear rise between two samples taken weeks apart. Your doctor uses this combined IgM and IgG result alongside your symptoms and possible exposure to contaminated water or soil to decide on next steps.
Testing both from a single blood sample means your doctor doesn't have to choose one antibody type or wait for a second visit to check the other, since IgM and IgG rise on different timelines during the illness.
This pattern generally points toward an earlier stage of infection, since IgM typically appears before IgG does.
This can suggest the illness is further along, or that the antibody response has had more time to develop, though timing varies between people.
Not definitively. It's a screening step, and health guidance treats the microscopic agglutination test, run at specialised reference laboratories, as the confirmatory standard.
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.
Most commonly through contact with water, soil, or surfaces contaminated by the urine of infected animals, with risk rising after flooding or heavy rain, according to CDC guidance.
No. No special preparation, including fasting, is needed before this blood draw.
The microscopic agglutination test, available at specialised reference laboratories, is used to confirm a positive screening result.