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For Healthcare Professionals

Clinical Description and Diagnosis

In Infants

RSV infection can cause a variety of respiratory illnesses, and these illnesses sometimes cause fever. RSV infection most commonly causes a cold-like illness, but can also cause bronchitis, croup, and lower respiratory infections like bronchiolitis and pneumonia. Twenty-five to 40 out of every 100 infants and young children infected with RSV for the first time will show signs of pneumonia or bronchiolitis. Premature infants, very young infants, those with chronic lung or heart disease, and those with suppressed immune systems have a greater chance of having more severe disease such as a lower respiratory tract infection. Infection without symptoms is rare among infants.

Infants with a lower respiratory tract infection typically have a runny nose and a decrease in appetite before any other symptoms appear. Cough usually develops 1 to 3 days later. Soon after the cough develops, sneezing, fever, and wheezing may occur. In very young infants, irritability, decreased activity, and apnea may be the only symptoms of infection.

Most otherwise healthy infants who are infected with RSV do not need hospitalization. Those who are hospitalized may require oxygen, intubation, and/or mechanical ventilation. Most improve with supportive care and are discharged in a few days.

In Adults

Symptomatic RSV infections may occur in adults, particularly in healthcare workers or caretakers of small children. Disease usually lasts less than 5 days, and symptoms are usually consistent with an upper respiratory tract infection and can include a runny nose (rhinorrhea), sore throat (pharyngitis), cough, headache, fatigue, and fever.

Some high-risk adults, such as those with certain chronic illnesses or immunosuppression, may have more severe symptoms consistent with a lower respiratory tract infection, such as pneumonia.

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Laboratory Testing

Several different types of laboratory tests are available for diagnosis of RSV infection. Rapid diagnostic assays performed on respiratory specimens are available commercially. Many clinical laboratories currently use antigen detection tests and/or molecular diagnostic testing. The sensitivity of antigen detection tests generally ranges from 80% to 90% in children, but is less sensitive in adults. Healthcare professionals should consult experienced laboratorians for more information on interpretation of results.

Reverse transcriptase-polymerase chain reaction (RT-PCR) assays are now commercially available for RSV. The sensitivity of these assays often exceeds the sensitivity of virus isolation and antigen detection methods. Laboratorians should consider using highly sensitive RT-PCR assays, particularly when testing older children and adults, because they may have low viral loads in their respiratory specimens that will not be detected using antigen detection tests.

Serologic tests are used less frequently for routine diagnosis. Although useful for seroprevalence and epidemiologic studies, laboratorians cannot diagnose RSV in time to guide patient care by using paired acute- and convalescent-phase sera to demonstrate a significant rise in antibody titer to RSV.

Prophylaxis and High-Risk Groups

Palivizumab is a monoclonal antibody recommended by the American Academy of Pediatrics (AAP) to be administered to high-risk infants and young children likely to benefit from immunoprophylaxis based on gestational age, certain underlying medical conditions, and RSV seasonality. It is given in monthly intramuscular injections during the RSV season, which generally occurs during fall, winter, and spring in most locations in the United States.

On July 28, 2014, AAP released updated guidance for palivizumab prophylaxis among infants and young children at increased risk of hospitalization for RSV infection. For specific and the latest palivizumab guidance, please consult the AAP policy statement. An accompanying AAP technical report provides additional context and rationale for the guidance.

Healthcare-associated Pneumonia

CDC provides recommendations for preventing healthcare-associated pneumonia, including RSV. State health departments and institutions may have their own individual guidance as well. See the Recommendations of CDC and the Healthcare Infection Control Practices Advisory Committee for more information.

The Virus

Respiratory syncytial virus (RSV) was discovered in 1956 and has since been recognized as one of the most common causes of childhood illness. The virus is a member of the family Paramyxoviridae and the subfamily Pneumovirinae. It is an enveloped RNA virus, and two strains (subgroups A and B) are recognized, the clinical significance of which is unclear.

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