Have you considered RSV when diagnosing your patients?
The majority of lower respiratory tract infections in children are caused by viruses, and RSV is generally recognized as the most frequent agent responsible for these infections.³ The RSV Info Center has provided information to help healthcare providers from all medical disciplines identify, diagnose, treat and prevent RSV infection in patients.

Identifying Respiratory Syncytial Virus
RSV is a labile paramyxovirus that produces a characteristic fusion of human cells in tissue culture--the syncytial effect. Two subtypes, A and B, have been identified. Subtype B are characterized as the asymptomatic strains of the virus that the majority of the population experiences. The more severe clinical illnesses involve Subtype A strains, which tend to predominate in most outbreaks.¹

RSV affects the upper and lower respiratory tracts, but is most prevalent in lower respiratory illnesses such as pneumonia and bronchiolitis. RSV bronchiolitis is one of the severe illnesses caused by RSV and is associated with clinical signs and symptoms of small airway obstruction.⁴ Bronchiolitis begins with mild symptoms of an upper respiratory tract infection and progresses to include cough, wheeze, onset of dyspnea, increased respiratory rate and retractions of the respiratory muscles, indicating lower respiratory tract involvement.¹ Airway obstruction can be extremely dangerous, especially in infants who have smaller peripheral airways than adults, so it is important to know the warning signs of bronchiolitis in order to manage the illness before it becomes life-threatening.

RSV is also one of the most common causes of pneumonia in young children. The incidence is greatest from birth to age three. Clues to a diagnosis of pneumonia may be the finding of crackles, respiratory distress and dullness to percussion.³

Who is at risk for RSV infection?
The National Center for Infectious Diseases and the Centers for Disease Control recommend that during the RSV season, healthcare providers should consider RSV as a cause of acute respiratory disease in both children and adults.⁵ Pneumonia and bronchiolitis, the most severe infections caused by RSV, are prevalent in infants aged 2 to 6 months, but children of any age with underlying cardiac or pulmonary disease or who are immunocompromised are at risk for serious complications from RSV infection.⁵ In patients with pneumonia or bronchiolitis who also have an underlying condition including bone marrow or organ transplantation, and T-cell lymphoma, RSV must be considered in the diagnosis.^6,7

Other factors contributing to increased risk of developing serious RSV infection include:

• premature infants and infants less than 6 weeks of age
• infants with congenital heart disease
• infants with chronic lung conditions including bronchopulmonary dysplasia and cystic fibrosis
• immunodeficiency
• lower socioeconomic status; crowded living conditions
• exposure to passive cigarette smoke
• attendance in day care setting
• presence of older siblings in the home
• infants who were not breastfed

Clinical Presentation
Typically, RSV bronchiolitis presents with a two to three day "prodromal" phase, which resembles a common viral upper respiratory tract infection.¹

Distinct symptoms of RSV bronchiolitis include:

• Rhinorrhea (runny nose)
• Wheezing and coughing (can persist for several months in severe infections)
• Irritability and restlessness (usually in those with impending respiratory failure)
• Low grade fever (102°F); but temperatures can be as high as 104°F when another illness, such as otitis media is present.
• Nasal flaring and retractions (intercostal, subcostal, and sternal) are indicative of airway obstruction. The chest may appear hyperexpanded and be hyperresonant to percussion. As a result of hyperexpansion of the lungs, the liver and spleen may be palpable several centimeters below the costal margins.
• X-ray findings are not pathognomonic, but often show air trapping and hyperinflation or appear normal.⁸
• Apnea, usually as an initial presenting symptom in short episodes. It occurs in approximately 20% to 25% of young infants.
• Circumoral and nailbed cyanosis (severely affected infant)

In the majority of patients with RSV bronchiolitis, symptoms resolve within five to seven days. However, this does not exclude the patient from being classified as "severely infected" and patients with underlying illness or disease states should be considered for early treatment with an antiviral agent.

Confirmation of RSV
For confirmation of RSV, proper testing of the patient's respiratory secretions will:

1. Positively identify RSV 
2. Rule out bacterial infection 

Nasopharyngeal secretions containing epithelial cells are necessary for positive diagnosis of severe RSV infections.⁸ Although viral isolation and subsequent culture from respiratory secretions may have long been considered the gold standard for diagnosing RSV, specific confirmation generally requires several days, presenting a dilemma for patients who may require immediate and aggressive treatment. A faster procedural time would allow patients diagnosed with RSV to begin therapy sooner, increasing their chances of a more rapid and complete recovery.

Transmission
Outbreaks of disease caused by RSV occur on a yearly basis, most commonly during the winter months, with the epidemics lasting approximately five months.^1,9 RSV is easily transmitted via large, aerosolized respiratory particles, or through contact with nasal secretions, and may even be transmitted indirectly by contact with contaminated objects, such as bathroom fixtures or even clothing. The most common sites of innoculation are the eyes and nose.⁹

Since RSV is relatively easy to transfer through casual contact, family members often pass it on to one another. Hospital staff are also frequent vectors in viral transmission. A simple and effective means of preventing disease spread both at home and in an institutional environment is good hand washing.

Another factor making the spread of RSV almost unavoidable is the period of viral shedding. Viral shedding may occur one to two days before symptoms become apparent and last as long as two weeks after symptom onset. This period is significantly greater and more prolonged for children with defective cellular immunity.¹ The incubation period is three to five days for most patients.

Again, the added risk posed by this potentially long period of viral shedding can be reduced by early diagnosis and treatment of RSV infection. Since disease can be spread before symptoms even appear and after they disappear, it is important to know the risk factors of RSV infection as well as the timing of the peak RSV infection season in your area. This will help physicians decide to test for RSV and subsequently manage the illness at its early stages.

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