Respiratory infections are among the most common illnesses among humans. A prevalent respiratory infection is RSV, or respiratory syncytial virus. While the illness is most common in infants and children, the infection is also capable of causing disease in teens and older adults. Though it's often mild and runs its course over a week, it is capable of causing severe symptoms in newborns, young infants, and people with compromised immunity. Testing for RSV is extremely important in individuals where the seemingly mild upper respiratory tract infection can lead to complications such as pneumonia. 

RSV is a seasonal illness that spreads during the winter months. Because it’s a communicable disease, RSV often jumps from person to person during outbreaks. Given that its symptoms are similar to other respiratory illnesses, testing for RSV becomes integral in both containing the spread and for accurate identification. In this article, we describe the symptoms of the illness and  why testing is suggested. We also discuss tests such as the RSV PCR test, which helps doctors diagnose the illness. 

RSV & Its Symptoms

• RSV is an RNA virus that causes upper respiratory tract infections. While it often restricts itself to the upper regions of the respiratory apparatus, it can sometimes lead to severe complications such as bronchiolitis, croup, and even pneumonia in young infants and adults that have weak immunity. 
• The disease spreads through the inhalation of droplets that contain the virus, or by coming in close contact with infected people. The virus is also known to spread through contaminated surfaces that house the disease-causing viral particles. 
• Like currently prevalent diseases such as COVID-19, the best way to prevent RSV is to maintain social distancing, wear masks, and frequently wash hands. 
• RSV is known to infect both adults and infants, however, it is often self-limiting in adults due to their fully developed immunity. Infants, on the other hand, are at greater risk of developing severe illness due to their immune systems being rudimentary. Regardless, severe RSV infections are rare, even in infants. 
• RSV lab tests are conducted in both adults and infants, whether to assess an outbreak or to diagnose the exact cause of serious respiratory distress.
• The most common symptoms of  respiratory syncytial virus include: 
• Cough: Due to the involvement of the respiratory system, cough is often noted to be a prevalent symptom among those infected by RSV. 
• Fever: Like any other infection, RSV also causes fever. The body, in an attempt to kill the virus, releases inflammatory chemicals and raises body temperature. 
• Runny nose: Similar to the common cold, RSV causes rhinitis or nasal inflammation that results in a runny nose. 
• Sneezing: The body tries to expel the virus from the respiratory system, causing sneezing. 
• Chest Congestion: RSV infection can sometimes spread to the lower portions of the respiratory tract and lead to chest congestion. 
• Malaise & Fatigue: Like any other viral infection, RSV drains the body of its energy. The immune response and the circulating inflammatory chemicals lead to body pain and exhaustion. 
• Individuals that suffer from severe illness may face serious symptoms that require immediate medical attention. These include: 
• Breathlessness: Young infants and immunocompromised adults might face severe breathlessness in the wake of an RSV infection that invades their lower respiratory tracts. This might happen either due to fluid filling up in the bronchial tree or between the lungs and pleura. Breathing is also shallow and fast, indicating insufficient air reaching the lungs in a single breath. 
• Barking Cough & Wheezing: Especially seen in young children, a barking cough is an important sign indicating severe chest infection. The doctor might order an RSV PCR test to confirm their aspersions in case other symptoms and external conditions are also in line with their provisional diagnosis. A whistling or crackling sound following exhalations is another sign to watch out for.
• Pneumonia: This symptom arises in individuals with severely compromised immunity and premature infants. Pneumonia occurs due to the inflammation of the air sacs in the lungs. These sacs then fill up with fluid or pus, leading to breathing difficulties. 
• Croup: An inflammation of the upper portions of the respiratory tract is called a croup. It occurs in children and reduces the width of the breathing passage, making it hard to breathe. A barking cough often occurs in conjunction with this symptom. 
• Bronchiolitis: Another symptom exclusive to young infants and children, bronchiolitis occurs due to the inflammation of the bronchioles - small tubes that carry air into the lungs and out. Bronchiolitis is commonly caused by viruses such as RSV. The inflammation constricts their effective space and makes it difficult to breathe. 
• Blue discoloration in the extremities: This is one of the most serious symptoms in a severe RSV infection that denotes insufficient oxygen supply. If you notice blue discoloration in the lips, fingers, or toes, reach out to the doctor immediately. 

RSV Tests

• Before proceeding to the laboratory analyses and RSV-specific tests, the doctor will first conduct a general examination to ascertain the nature of the symptoms. 
• Inform the doctor of all your symptoms and signs right from when you first encountered them. In case your child is ill, describe the child’s behavior and symptoms in detail before the examination to give the doctor a clear picture of the child’s health. 
• Often, doctors will correlate the symptoms with information about any nearby outbreaks of RSV to make a diagnosis. However,  this isn’t sufficient in many cases, and your doctor might suggest you get an RSV PCR or an RSV antigen test for confirmation. 
• Tests for the illness are usually recommended only in children, vulnerable individuals, and when there’s an outbreak in the local community. 
• So, how is RSV tested? The illness can be detected using these forms of testing: 
• RSV PCR or Molecular Testing: The RSV PCR test detects viral DNA in your sample. Mechanisms of the test magnify the DNA from the sample to several times its original size and search for viral DNA coded within it. PCR tests are capable of detecting even small amounts of viral DNA inserted into host cells, making them precise and reliable. Currently, RSV PCR tests remain the most trusted methods for confirming an infection, making them the gold standard. 
• RSV Antigen Test: These tests look for specific proteins present on the surface of the virus to deliver confirmation of the illness. The samples often include fluids from the nose or the back of the throat. Unlike RSV PCR tests, antigen tests are quicker, although their accuracy can be altered in older patients that have lower viral counts in organs such as the nose. 
• RSV Antibody Test: This test detects the antibodies generated by the body’s immune system to combat RSV. It requires a blood sample for analysis and is not reliably accurate. While being time-consuming, it is also not specific when it comes to detection. Sample collection is often cumbersome in young infants, and the time taken to deliver results makes this test’s accurate counterparts more relevant for quick disease detection. 
• Viral Culture: This is a rare test that is usually conducted only to check for the strain of RSV causing an outbreak. Cultures are usually used only for academic purposes and not for diagnosis.  

How to Test for RSV?: Sample Collection

• Sample collection for RSV tests is straightforward. Apart from the RSV antibody test, all tests entail painless collection methods. 
• The process of collecting samples involves:
• Nasopharyngeal Swab: This collection method entails the lab tech or the doctor inserting a swab into the back of the nose to collect samples of both the mucosal cells and the fluid in the area. The swab is also inserted into the back of the throat to collect samples from two different, yet connected areas. 
• Aspirate: A small amount of nasal discharge is extracted from the nasal passage using a small suction device. The collected discharge can then be sent to the lab for further testing and confirmation. 
• Nasal Wash Specimen: In this test, the doctor will insert a bulb-like device filled with saline into one of the nostrils and slowly squeeze the bulb to introduce the saline into the nostril. After a small period of squeezing out the saline, the doctor will release the bulb to draw the saline solution back into it. The resulting fluid will contain samples of the nasal fluid and mucosal cells that can be useful in testing and disease detection. 

How Long Does an RSV Test Take?

• RSV PCR tests such as those conducted at Lenco often take between 24 and 48 hours to show results. 
• On the other hand, antigen tests are much quicker and deliver tests within an hour. However, the former being more precise, doctors often only recommend PCR tests in patients of specific concern. Doctors understand that antigen tests are accurate in children due to the presence of more RSV pathogens in their upper respiratory tracts when compared to older adults. 
• Antibody tests are usually avoided as they can take up to 72 hours for results to show up. That apart, the test also involves pain and a certain degree of discomfort to the patient as it requires blood sample collection. 

RSV Test Results

• Negative RSV PCR tests are often confirmative and do not require any further testing. 
• On the other hand, negative antigen tests in adults are dubious due to false negatives. Doctors will often follow this up with an RSV PCR test for confirmation. 
• RSV PCR positives are confirmatory for the disease and allow your doctor to commence symptomatic treatment for the illness. 

RSV, despite being a common and mild illness, can turn into a vicious pathogen in vulnerable individuals and babies. If you’re concerned about yourself or your child having caught an RSV infection, reach out to your doctor for further information and health advice.