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RSV

Formal name: Respiratory Syncytial Virus
Related tests: Influenza tests, Pertussis, Strep throat

At a Glance

Why Get Tested?

To determine whether an infant, an elderly patient, or an immunocompromised patient has respiratory syncytial virus (RSV) and to help determine whether or not RSV season has started in your community

When to Get Tested?

When it is RSV season (late fall through early spring) and your doctor wants to determine whether your runny nose, congestion, coughing and/or difficulty breathing are due to RSV or to other causes

Sample Required?

Usually a nasal aspirate or nasal wash; occasionally a nasopharyngeal (NP) swab

The Test Sample

What is being tested?

RSV testing is used to detect respiratory syncytial virus, a common viral respiratory infection. RSV tends to be seasonal, causing community epidemics in young children, older adults, and immunocompromised patients that typically begin in November or December and disappear in early spring. In these high-risk groups, RSV can cause pneumonia and bronchiolitis. Affected patients may have symptoms such as severe coughing, difficulty breathing, and high fevers. Each year more than 100,000 people are hospitalized with RSV infection and, according to the Centers for Disease Control and Prevention, about 11,000 people a year die from its complications, with most deaths occurring in the elderly.

RSV testing detects virus that is being shed in the respiratory/nasal secretions of an infected person. Since detectable amounts of virus are usually only shed for the first few days of an infection, most testing must be done during this time period. There are several methods to test for the virus, but rapid RSV antigen testing is by far the most popular. Rapid RSV antigen tests are frequently performed on-site, in the doctor’s office or the emergency room, with most results available within an hour. In some cases, the sample may be collected and sent to a laboratory for a more sensitive testing method. Results of these RSV tests are usually available the same day.

Occasionally, a doctor will order a viral culture (to grow the RSV virus) or a test to detect the virus’s genetic material. These tests have the advantage of identifying not only the RSV virus but also other respiratory viruses that may be present. The main disadvantages of these tests are that they are not available in every laboratory and that the results take longer than the rapid RSV test. This makes them less clinically useful for evaluating an individual patient, but they can be useful for documenting that RSV or another virus, such as influenza, has reached a community and for identifying outbreaks in particular populations, such as a nursing home, school, or neighborhood.

How is the sample collected for testing?

Sample collection technique is critical in RSV testing. The best and most frequently used sample is a nasal aspirate or wash. A syringe is used to push a small amount of sterile saline into your nose, then gentle suction is applied (for the aspirate) or the resulting fluid is collected into a cup (for a wash).

Sometimes, a nasopharyngeal (NP) swab is used, although it is not preferred because of decreased virus quantity in the sample. The NP swab is collected by having you tip your head back, then a Dacron swab (like a long Q-tip) is gently inserted into one of your nostrils until resistance is met (about 1 to 2 inches in), then rotated several times and withdrawn. This is not painful, but it may tickle a bit and cause your eyes to tear.

NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.

Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed.

The Test

How is it used?

RSV testing is usually used during the RSV season to help diagnose patients who have moderate to severe symptoms and lower respiratory tract involvement. It is primarily ordered on infants (between the ages of 6 months and 2 years), elderly patients, and those with compromised immune systems, such as those who have pre-existing lung disease or who have had an organ transplant. Older children and the rest of the general population are not routinely diagnosed or tested because most of them will experience only relatively mild upper respiratory infections with symptoms such as a runny nose, sneezing, coughing, sore throat, and fever.

RSV testing is also used to document and track the spread of RSV in the community. Since most cases of RSV are self-limiting, community health efforts are focused on containing and preventing the spread of RSV as much as possible to minimize the chance of spreading the virus to high-risk patients. Treatment of RSV is primarily supportive, minimizing pain and fever and easing breathing. Those with mild symptoms may only be tested for RSV if it is necessary to help track its spread. RSV testing is frequently ordered along with influenza testing if both viruses are known to be present in the community. These tests are used to detect the presence of RSV or influenza and to evaluate the likelihood that an individual patient’s symptoms may be due to one of these viruses or to another cause, such as a bacterial infection.

Viral cultures or genetic respiratory virus testing may sometimes be used to help track RSV outbreaks and to identify other viral infections that may cause clinical symptoms similar to RSV.

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When is it ordered?

RSV tests are ordered almost exclusively during “cold and flu season” – late fall to early spring. They are ordered when a patient, usually an infant or elderly person, presents with a lower respiratory infection and symptoms such as wheezing, severe coughing, rapid breathing (primarily in infants), fevers, headaches, a runny stuffy nose, and a sore throat.

When RSV has already been identified in the community, the doctor may order a rapid RSV test to confirm the suspected diagnosis in the symptomatic patient. If influenza is also in the community, RSV testing may be ordered along with influenza testing to determine which virus the patient has. The doctor may also order bacterial tests, such as a strep test (to check for group A streptococcus, the bacteria that cause strep throat), when the cause of the infection is unclear.

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What does the test result mean?

If a rapid RSV test is positive, then it is likely that the patient has respiratory syncytial virus. A positive viral culture or genetic viral test can confirm the presence of RSV in the community. A positive RSV test cannot, however, tell a doctor how severe a patient’s symptoms are likely to be or how long ago they were infected. Symptoms usually appear 4-6 days after infection.

Negative rapid RSV tests may mean that you have something other than RSV or that there is not sufficient virus in the specimen to allow it to be detected. This may be due to either a poor specimen collection or because you are not shedding detectible levels of virus into your respiratory secretions. Adults tend to shed less virus than infants do, and those who have had RSV for several days will shed less than those with a more recent infection.

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Is there anything else I should know?

Most RSV infections will go away within 1 or 2 weeks. People can be re-infected with different strains of RSV from year to year, although subsequent infections tend to be less severe than the first/primary infection. Since most RSV infections are mild, symptoms from these re-infections are usually attributed to “a cold.” These cases of RSV are usually not formally diagnosed and are often treated by the patient with over-the-counter cold remedies for symptom relief.

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Common Questions

1.  Is there a blood test for RSV?

There are blood tests for RSV antibodies – the immune system’s response to the virus. These tests can detect previous exposure to RSV, but they are not usually considered clinically useful for diagnosing an active case of RSV.

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2.  Is there a vaccine like the flu shot to prevent RSV?

Not currently, although it is considered a high priority by researchers.

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3.  Are antibiotics useful when I have RSV?

No, RSV is due to a virus – not a bacteria – so antibiotic therapy is not indicated or helpful. There is a short-term drug therapy that is given to some high-risk patients. It does not prevent or cure RSV infection, but it minimizes lower respiratory tract involvement, reducing the need for hospitalization in affected patients. This immunotherapy may be given to neonates in the intensive care nursery to protect them during RSV season. Premature infants can be especially vulnerable to RSV.

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Ask a Laboratory Scientist

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This was not an easy step for us to take, as the volunteers on the response team are dedicated to the work they do and are often inspired by the help they can provide. We are actively seeking to expand our capability so that we can again accept and answer all user questions. We will accept and respond to the same limited number of questions tomorrow, but expect to resume the service, 24/7, as soon as possible.

Article Sources

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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.

Sources Used in Current Review

Wu, A. (2006). Tietz Clinical Guide to Laboratory Tests, Fourth Edition. Saunders Elsevier, St. Louis, Missouri. Pp 1596-1597.

Forbes, B. et. al. (© 2007). Bailey & Scott’s Diagnostic Microbiology, Twelfth Edition: Mosby Elsevier Press, St. Louis, Missouri. Pp 730-731, 745.

Rauch, D. (2007 July 26, Updated). Respiratory syncytial virus (RSV). MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/001564.htm. Accessed on 7-29-08.

Mozingo, T. (2008, Winter). RSV When It’s More Than Just a Cold. Healthy Children, American Academy of Pediatrics [On-line information]. PDF available for download at http://www.aap.org/family/healthychildren/08winter/HC-winter08-rsv.pdf through http://www.aap.org. Accessed on 7-29-08.

Mayo Clinic Staff (2007 August 1). Respiratory syncytial virus. MayoClinic.com [On-line information]. Available online at http://www.mayoclinic.com/health/respiratory-syncytial-virus/DS00414 through http://www.mayoclinic.com. Accessed on 7-29-08.

(© 2007). Respiratory Syncytial Virus. American Lung Association [On-line information]. Available online at http://www.lungusa.org/site/apps/nlnet/content3.aspx?c=dvLUK9O0E&b=2060721&content_id={AC999AD1-9FB2-4310-A642-FD850C2E82AC}&notoc=1 through http://www.lungusa.org. Accessed on 7-29-08.

(© 2007). Respiratory Syncytial Virus Fact Sheet. American Lung Association [On-line information]. Available online at http://www.lungusa.org/site/apps/nlnet/content3.aspx?c=dvLUK9O0E&b=2060721&content_id={DEA9A6D1-58D5-4E47-8F36-6E0AAB65B977}&notoc=1 through http://www.lungusa.org. Accessed on 7-29-08.

(2008). Respiratory Syncytial Virus. American Lung Association Lung Disease Data: 2008 [On-line information]. PDF available for download at http://www.lungusa.org/atf/cf/%7B7a8d42c2-fcca-4604-8ade-7f5d5e762256%7D/ALA_LDD08_RSV_FINAL.PDF through http://www.lungusa.org. Accessed on 7-29-08.

Sources Used in Previous Reviews

Thomas, Clayton L., Editor (1997). Taber’s Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA [18th Edition].

Pagana, Kathleen D. & Pagana, Timothy J. (2001). Mosby’s Diagnostic and Laboratory Test Reference 5th Edition: Mosby, Inc., Saint Louis, MO. (pp 826-827).

(2003 April). “Flu” Season Explodes into “Respiratory Virus” Season. Stanford University Medical Center, LAB Letter [On-line newsletter]. PDF available for download at http://www.stanfordhospital.com/pdf/labLetterApril2003.pdf through http://www.stanfordhospital.com.

(2003 November 28, Reviewed). Respiratory Syncytial Virus. CDC, National Center for Infectious Diseases, Respiratory and Enteric Viruses Branch [On-line information]. Available online at http://www.cdc.gov/ncidod/dvrd/revb/respiratory/rsvfeat.htm through http://www.cdc.gov.

Izenberg, N. (2003 July, Reviewed). Respiratory Syncytial Virus. KidsHealth for Parents, Nemours Foundation [On-line information]. Available online at http://kidshealth.org/parent/infections/lung/rsv.html through http://kidshealth.org.

(2003 January 7). CDC Finds Annual Flu Deaths Higher Than Previously Estimated. CDC Media Relations [On-line Press Release]. Available online at http://www.cdc.gov/od/oc/media/pressrel/r030107.htm through http://www.cdc.gov.

Graham, P. (2003 October 30, Updated). Respiratory syncytial virus (RSV). MedlinePlus Health Information, Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/001564.htm.

Polak, M. (2004 April 13). Respiratory Syncytial Virus (RSV): Overview, Treatment, and Prevention Strategies. Medscape, From Newborn & Infant Nursing Reviews [On-line journal]. Available online at http://www.medscape.com/viewarticle/472399?src=search through http://www.medscape.com.

Estrada, B. (2004 January 05). Pediatric Bulletin, What's New in RSV. Medscape, Infect Med 20(11):522, 2003. [On-line journal]. Available online at http://www.medscape.com/viewarticle/465432?src=search through http://www.medscape.com.

Park, J. and Barnett, D. (2002). Respiratory Syncytial Virus Infection and the Primary Care Physician. Medscape, South Med J 95(3):353-359, 2002 [On-line journal]. Available online at http://www.medscape.com/viewarticle/431615 through http://www.medscape.com.

(© 2004). Respiratory Syncytial Virus Antibodies, IgG and IgM. ARUP's Guide to Clinical Laboratory Testing [On-line information]. Available online at http://www.arup-lab.com/guides/clt/tests/clt_176b.jsp#1146861 through http://www.arup-lab.com.

(© 2004). Respiratory Viruses. ARUP's Guide to Clinical Laboratory Testing [On-line information]. Available online at http://www.arup-lab.com/guides/clt/tests/clt_177b.jsp#1146881 through http://www.arup-lab.com.

(2003 May). BD Directigen RSV. Becton, Dickinson and Company (BD) [Test Package Insert].