Respiratory Syncytial Virui and the Use of Ribai Erupting every year during the winter months, this myxovirus has an affinity for the tiny airways of infants and young children. By Harriet Miller

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espiratory syncytial virus (RSV) accounts for one-half of all hospital admissions for respiratory diseases in infants and is the major viral cause of nosocomial illness in pediatric inpatients (1,2). RSV can cause both upper and lower respiratory disease and is the major cause of bronchiolitis and pneumonia in infants less than one year old. Complications of respiratory failure, apnea, and death occur more frequently in high-risk infants with prematurity, perinatal complications, congenital heart disease, pulmonary dysplasia, and immunosuppression. Mortality rates for children with heart disease approach 30 percent and 70 percent with heart disease and pulmonary complications (3). Seasonal in occurrence, RSV occurs in annual epidemics between December and April. Although it affects any age group, RSV is found with greatest severity in small children and infants less than two years of age. By age two, nearly 100 percent of children will have acquired RSV infection. Immunity to this pathogen is short-lived and children can become reinfected later in life, even into adulthood (4). RSV is an RNA-containing myxovirus first isolated in chimpanzees in 1956 and later in humans in 1957 (5). RSV is transmitted through viral shedding by large droplet nuclei from injected respiratory secretions and by self-inoculation after touching contaminated surfaces (6). Although considered a labile virus sensitive to pH and temperature changes, it can remain viable on skin surfaces at room temperature for at least eight hours, countertops after six hours, and tissue paper after 30 minutes (7). Studies have shown that inoculation can occur through the eyes or nose, but not the mouth. Aerosolization may occur within three feet (8). In other words, inoculation through aerosolization (sneezing) is possible within three feet of an infected person. 238

Infection control for RSV involves limiting nosocomial transmission of the virus by hospital staff and susceptible infants and children, particularly those at high risk. Hospital personnel caring for infected infants need to avoid caring for uninfected infants, or at least limit contact with high-risk patients, such as those with congenital heart disease or pulmonary dysplasia. Researchers recommend careful handwashing, the use of disposable gloves, gowns, masks, and goggles when providing direct care for infected children. Researchers also suggest isolating infected patients one to a room, but consider grouping these patients permissible (9). Symptoms More Severe in Infants RSV generally occurs as an upper respiratory infection following an incubation period of two to eight days. The infant or child becomes symptomatic with some combination of fever, cough, pharyngitis, nasal congestion, and otitis media. A few days later, 40-50 percent of infected infants will manifest lower respiratory tract infections. Necrosis of the bronchiole epithelium associated with inflammation of the smaller airways is the pathologic hallmark of RSV and results in airway obstruction (10). At this point, clinicians can observe symptoms such as dyspnea, tachypnea, retractions, cyanosis, wheezing, apnea, and hypoxemia. Additionally, infected infants display poor feeding and irritability (see Signs and Symptoms of Respiratory Syncytial Virus) (11). Adults who care for children may be infected, but in adults, RSV is asymptomatic or causes only common cold symptoms or mild pharyngitis. Reinfection is frequently benign and the lower respiratory tract is rarely involved. RSV has a predilection for small airways and its clinical manifestations are less severe in adults than in infants and young children (12). MCN Volume 17 Seplember/October 1992

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RSV is confirmed by the appropriate signs and symptoms of RSV and identification of the virus in nasal, pharyngeal, or pulmonary secretions. Laboratory diagnosis can be obtained by viral cultures, which take several days to complete, or antigen detection assays (enzyme-linked immunoassay or immunofluorescence), which can be obtained within six hours (13). Until recently, there has been no known treatment or vaccine for RSV. In 1986, aerosolized ribavirin was approved by the Food and Drug Administration for the treatment of RSV in hospitalized children. Ribavirin is thought to interfere with the expression of messenger RNA, thereby inhibiting viral protein synthesis. Infants with proven RSV infection receiving aerosolized ribavirin showed a significant improvement in degree of hypoxemia, as measured by arterial blood gas samples, and diminished viral shedding (14). Ribavirin aerosol treatment is currently recommended for infants and young children by the American Academy of Pediatrics Committee on Infectious Diseases in the categories outlined in "Patients Recommended for Ribavirin Use" (15). MCN Volume 17 September/October 1992

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Respiratory syncytial virus and the use of ribavirin.

Respiratory Syncytial Virui and the Use of Ribai Erupting every year during the winter months, this myxovirus has an affinity for the tiny airways of...
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