Ricktyphusigmmsmtser

Published: August 9, 2026Updated: August 17, 2026

A blood test that detects IgM antibodies against Rickettsia bacteria (typhus group) to help diagnose recent or current typhus infection.

Quick summary

{"This test looks for IgM antibodies, which are your body's first response to a Rickettsia infection","The typhus group includes epidemic typhus (body lice) and murine typhus (fleas)","A positive result suggests a recent infection within the past 1-2 weeks","Symptoms typically include high fever, severe headache, and a rash","Early diagnosis and treatment with antibiotics is important"}

Medically reviewed by WellAlly Editorial TeamLast reviewed August 17, 2026Editorial policy

Key facts at a glance

LOINC: 110691-3
Short code: RICK-TG-IGM
Synonyms: Rick Typhus IgM Msmt Ser
Category: cardiac
Sample: serum
Container: Serum separator tube (SST/gel tube) or plain red top tube
Units: N/A
Ref low: 0.8
Ref high: 1.2
Critical range: — – 10000 N/A
Fasting: false
Population: adult
Sex: all
Age range: 0–120 years
Method: Enzyme-Linked Immunosorbent Assay (ELISA) for IgM antibody detection
CPT: 86757 (Rickettsia antibody, IgM)
SNOMED: 186747009 (Rickettsia infection of cardiovascular system) or 40930008 (Rickettsial disease)
Specimen volume: 1.0-2.0 mL of serum minimum
Stability: Room temperature: 24-48 hours; Refrigerated (2-8°C): 5-7 days; Frozen (-20°C or below): 2-4 weeks. Avoid repeated freeze-thaw cycles.
Hemolysis max: 50
Lipemia max: 60
Icterus max: 40
TAT: 24–72 hours
Order: routine

What is this test?

The Rickettsia Typhus Group IgM Antibody Test is a blood test that detects IgM antibodies against Rickettsia bacteria belonging to the typhus group. IgM antibodies are the first type of antibodies your immune system produces when fighting a new infection, making this test useful for detecting recent or current infections.

What is Typhus?

Typhus is a bacterial infection caused by Rickettsia bacteria. The typhus group includes two main types: epidemic typhus (caused by Rickettsia prowazekii, transmitted by body lice) and murine/endemic typhus (caused by Rickettsia typhi, transmitted by fleas from rats). These diseases are more common in areas with poor sanitation, overcrowding, or where people are exposed to rats and fleas.

Why is this test done?

Your healthcare provider may order this test if you have symptoms suggestive of typhus, such as: high fever (often above 102°F or 39°C), severe headache, muscle aches, rash (typically starting on the trunk and spreading outward), and chills. The test helps confirm whether your symptoms are due to a recent Rickettsia infection.

How is the test performed?

A healthcare professional will draw a small blood sample from a vein in your arm. This blood sample will be sent to a laboratory where technicians will look for IgM antibodies specific to Rickettsia typhus group bacteria. No special preparation is needed before the test.

Understanding your results

A positive IgM result indicates that your body has produced IgM antibodies against Rickettsia, suggesting a recent or current infection. A negative result means no IgM antibodies were detected, but this does not completely rule out infection, especially if it is very early in the illness. Your healthcare provider will interpret the results together with your symptoms and other test findings.

Reference range

Negative: < 0.8 AU (Arbitrary Units); Equivocal: 0.8-1.2 AU; Positive: > 1.2 AU. Alternatively, titers <1:64 considered negative, 1:64-1:128 equivocal, ≥1:128 positive for IFA method.N/A

Specimen: serum

No special preparation required. Fasting not necessary. Inform laboratory of recent infections, antibiotic therapy, or immunosuppressive conditions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Frequently asked questions

How long does it take to get results?

Results are typically available within a few days to a week, depending on the laboratory. Your healthcare provider will contact you with the results.

Do I need to fast before this test?

No, you do not need to fast before this test. You can eat and drink normally.

Is the test painful?

You may feel a brief pinch or mild discomfort when the blood is drawn, but this is usually well-tolerated. The discomfort is temporary and goes away quickly.

What happens if my test is positive?

If your test is positive, your healthcare provider will likely start you on antibiotic treatment immediately. Doxycycline is the standard treatment and is most effective when started early. Most people improve within 48-72 hours of starting antibiotics.

Can I get typhus more than once?

Yes, it is possible to get typhus more than once, especially with murine typhus. However, having had typhus may provide some immunity against the same type, though this immunity may not be lifelong.

How is typhus prevented?

Prevention includes: avoiding areas infested with rats, using insect repellent, wearing protective clothing, maintaining good hygiene, and controlling rodent populations. If you are traveling to areas where typhus is common, take preventive measures and consult your healthcare provider about potential risks.

Sources

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 17, 2026. · Read our editorial policy