Parainfluenza Tests
Reviewed
Also called: Human parainfluenza virus test, HPIV test, HPIV-1 test, HPIV-2 test, HPIV-3 test, Paraflu 1-4 PCR test
Parainfluenza tests check whether a parainfluenza virus is causing a respiratory illness. These viruses are common in spring, summer, and fall and can cause cold-like symptoms, croup, bronchitis, or pneumonia, especially in people with weakened immune systems or certain medical conditions. The most common test is a molecular (PCR) test that detects genetic material of the virus.
Specimen: Fluid from nose or lungs (nasal aspirate/wash, nasal or throat swab, sputum, or bronchoalveolar lavage)
Urgent safety information
An empty urgentWarning is correct for a routine test.
Why this test may be ordered
- You have symptoms of a respiratory illness and a condition that increases your risk of serious illness from parainfluenza (e.g., weakened immune system, heart or lung disorder, older age).
- You are hospitalized with community-acquired pneumonia and need to know if the cause is viral or bacterial.
Preparation and collection
No special preparation is needed for most parainfluenza tests. If you are having a bronchoalveolar lavage (BAL), you may need to fast for several hours before the test and arrange for someone to drive you home because you may receive medicine to help you relax.
A sample of fluid from your nose or lungs is collected. Methods include: nasal aspirate/wash (saline solution inserted and suctioned out), nasal or throat swab (swab inserted into the back of the nose or through the mouth), sputum sample (coughing up mucus from the lungs), or bronchoalveolar lavage (a thin tube inserted into the lung to collect fluid).
There is very little risk to having a parainfluenza test. A nasal aspirate or wash may feel uncomfortable but the effects are temporary. Nasal and throat swabs may cause a brief gagging feeling. A bronchoalveolar lavage (BAL) may cause a sore throat for a few days; serious problems such as bleeding, infection, or a partly collapsed lung are rare.
Understanding results
Your healthcare provider will interpret your test results. The following are general patterns; always discuss your specific results with your provider.
- Negative: No signs of parainfluenza viruses were found in your sample. Another illness is probably causing your symptoms. Limitation: A negative test result does not rule out a parainfluenza illness because there may have been too little virus in the sample to detect. Next step: Routine
- Positive: You likely have a parainfluenza infection. However, a positive result may not always mean you are currently ill. Limitation: It is possible for a PCR test to show signs of a virus even though you do not have enough virus in your body to make you sick. Next step: Routine
- Rapid antigen tests are less accurate and must be done within a week after symptoms begin.
- Viral culture tests take much longer than other tests.
- Blood tests are mainly used for research.
- A negative result does not rule out infection; a positive result may not always indicate active illness.
What to do next
Talk with your healthcare provider about what your test results mean and any follow-up care you may need.
- What do my test results mean for my condition?
- Do I need any additional tests?
- What symptoms should I watch for?
- When should I follow up with you?