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.
