Antibody to Measles Nucleocapsid Protein (Serum or Plasma)

Why This Test Might Be Ordered

Your healthcare provider may recommend this test if you have symptoms of measles (e.g., fever, rash, cough) or if you’ve been exposed to someone with measles. It can also be used for travelers, newborns, or individuals with weakened immune systems to check immunity status. Rarely, it may be part of screening for measles in outbreaks.

What to Expect Before the Test

No special preparation is needed. You’ll provide a blood sample (serum or plasma) via a simple venipuncture. If testing urine or saliva, follow your provider’s instructions for sample collection. Results are typically available within 24–72 hours.

What the Results Mean

Positive results indicate your immune system has detected measles antibodies, suggesting past infection or recent exposure. Negative results mean no detectable antibodies were found, which could mean you’ve never been exposed or vaccinated. Follow-up may include vaccination or monitoring for symptoms.

Common Causes of Positive Results

A positive result is most common after measles infection, but it can also appear after vaccination (especially in the first few weeks). Rarely, it may appear in people with weakened immune systems who have been exposed but haven’t yet developed symptoms.