Pathophysiology
1) respiratory tract disease with the most severe clinical conditions seen in newborns and infants 2) cause is infection with a virus in the Paramyxoviridae family 3) exists in types A and B with the antigenic difference owing to differences in the G protein
Signs and Symptoms
Infants and young children – 1) fever 2) rhinorrhea 3) cough 4) wheezing 5) rhonchi 6) rales 7) can progress to dyspnea, tachypnea, hypoxia Adults – 8) headache 9) sore throat 10) malaise Elderly – 11) pneumonia 12) bronchiolitis 13) tracheobronchitis
Characteristic Test Findings
Radiology – 1) hyperexpanded lung fields 2) infiltrates (can range from diffuse infiltrates to lobar consolidation) Laboratory – 3) definitive diagnosis is made by isolating the virus from respiratory secretions in infants and, in older children and adults, by positive serologic titers
Histology/Gross Pathology
1) single-stranded enveloped RNA virus 2) replication of virus causes fusion of neighboring cells into giant multinucleated syncytia 3) the major glycoproteins extending from the lipid envelope are G protein (attaches virus to cells) and F protein (facilitates the fusion of the viral and host membrane)
Associated Conditions
1) increased mortality of RSV with congenital heart disease, nephrotic syndrome, prematurity, bronchopulmonary dysplasia, immunosuppression 2) increased frequency of RSV with – daycare centers, transplant patients, institutionalized patients
Inheritance/Epidemiology
1) affects mostly infants and young children ) occurs in USA in late fall and winter and almost never seen in warmer months 3) easily transmitted person to person via fingers, fomites, and aerosols.
Treatment
1) for upper respiratory tract disease – general supportive care 2) for lower tract disease – suctioning, supplemental oxygen, and antibronchospastic agents 3) in severe cases, aerosolized ribavirin 4) prophylaxis in high-risk patients with IV immunoglobulin
Tips for USMLE
1) in adults, RSV reinfection is one of the causes of the “common cold” 2) think RSV is a 6 month-old baby is sent home from day care one day in early November with a fever, runny nose, cough, and slight wheezing on inspiration
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