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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 it can also cause bronchitis, croup, and lower respiratory infections like bronchiolitis and pneumonia. Of every 100 infants and young children with RSV infection, 25 to 40 (25% to 40%) will show signs of pneumonia or bronchiolitis. Premature infants, very young infants, and those with chronic (always present) lung or heart disease or with suppressed (weakened) immune systems have a greater chance of having a more severe infection 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, but 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.