Respiratory Syncytial Virus
Table of Contents
- What is Respiratory Syncytial Virus (RSV)?
- RSV in Alaska Native children
- Sequelae of severe RSV infections in Alaska Native children
- Current Prevention Methods
- Projects in Progress
- Future Plans
- References
What is Respiratory Syncytial Virus (RSV)?
RSV
is the most common cause of serious respiratory infections (mostly bronchiolitis [inflammation of the small airways in the lung] and pneumonia) in
infants and young children. Many of these children are hospitalized. Infants
less than 6 weeks old, and children with underlying conditions such as premature
birth, heart disease or lung disease, are much more likely to be hospitalized
with RSV. RSV is also causes cold-like symptoms and pneumonia in older children
and adults. RSV infection is quite common; virtually all children in the United
States have been infected with RSV by the age of 3 years [LaVia
et al, 1992].
Up to 126,300 children are hospitalized annually in the United States for bronchiolitis or pneumonia [Shay et al, 1999]. Annual RSV epidemics peak in February and are responsible for one-fourth to one-third of all pediatric hospitalizations for pneumonia [La Via et al, 1992] and one-half of the hospitalizations for bronchiolitis [Heilman, 1990]. Native American children have higher morbidity and mortality from acute respiratory infections than other U.S. children. Moreover, the mortality from pneumonia for Native American infants is twice that of infants in the general U.S. population [Indian Health Service, 1996].
RSV in Alaska Native children
RSV infection is a major cause of hospitalization in Alaska Native infants. A review of discharge diagnoses in four Alaska Native hospitals from 1986 to 1992 showed increasing hospitalization rates for bronchiolitis and RSV pneumonia. Active RSV surveillance in Southwest Alaska between 1993-96 showed a hospitalization rate of 156 per 1000 infants < 1 year of age [Karron et al. 1999]; this far exceeds U.S. reported rates [Shay et al. 1999]. RSV infection was the cause of one-third of all hospitalizations in children less than 3 years of age in Southwest Alaska. There was a young peak age of hospitalization in this population (0-2 months of age).
Children hospitalized with RSV infections were at high risk for further respiratory illnesses -19% of hospitalized children were readmitted with another RSV infection, and 34% were re-hospitalized with another acute respiratory infection within one year of the first RSV hospitalization. Rural Alaska Native children are at high risk of chronic lung disease including bronchiectasis; the relationship between severe RSV illnesses in infancy and these chronic diseases have not been determined.
Risk factors for RSV hospitalization in Southwest Alaska parallel those in other U.S. populations. Children with underlying medical conditions (prematurity, heart disease, lung disease) are over 6 times more likely to be hospitalized with RSV than other children. Additionally, household crowding (4 or more children in a home) increases the risk of RSV hospitalization, while breastfeeding decreases hospitalization risk [Bulkow, 2002].
Sequelae of severe RSV infections in Alaska Native children
In a recent 5 year follow-up of RSV hospitalized infants and their age-matched controls we found that hospitalization for RSV infection was associated with a significant increase in wheezing and lower respiratory infections during the first 4 years of life. The association decreased with age and was no longer significant by 5 years of age. However, hospitalization for RSV infection was associated with increased chronic bronchitis and respiratory symptoms including cough at 5-8 years of age.
Current Prevention Methods
Because RSV infection is ubiquitous, the Arctic Investigations Program and Native Tribal Corporations have focused their prevention efforts on severe RSV infections in very young infants and infants with underlying medical conditions:
- RSV prevention for high risk infants: In 1997, a formulation of RSV monoclonal antibody called palivis
- own to reduce RSV hospitalizations in high risk infants (primarily premature infants and infants with chronic lung disease). Palivisumab, given as monthly injections, was licensed in 1998 for use in high risk infants during RSV season. Since 1998, Alaska Native tribal corporations have provided monthly Synagis® injections to young infants with underlying medical conditions to prevent RSV hospitalizations in these very high risk infants.
Video:
In 1997 Arctic Investigations Program produced and distributed an informational
RSV video to parents in Southwest Alaska. The video describes the results
of the RSV study and recommends simple prevention strategies for all children:
reducing secondhand smoke exposure, handwashing, breastfeeding, and reducing
exposure of young infants to large groups of people.
Parent
education: Since 1997, nurses and physicians in hospitals operated by tribal
corporations have provided education to parents of newborns, especially
those with underlying medical conditions, about risk factors for RSV infection.
(Brochures produced by Channing L. Bete Co., Inc. and MedImmune, Inc.)
Projects in Progress
- Evaluation of the impact of palivisumab (Synagis®) on RSV hospitalizations in high risk Alaska Native infants (to be finished Fall 2002)
- Ongoing passive surveillance of RSV hospitalizations in Southwest Alaska to determine trends in seasonality, severity, and rate of RSV hospitalizations and evaluate interventions
- Evaluation of effects of RSV infection in infancy on health later in childhood
Future Plans
- Because of the high rate of RSV hospitalizations and the great expense of providing care for these children, the Arctic Investigations Program and Native Health corporations are together assessing the feasibility of studies to determine the efficacy of candidate RSV vaccines or new monoclonal antibody products.
References
- LaVia WV, Marks MI, Stutman HR. Respiratory syncytial virus puzzle: clinical features, pathophysiology, treatment, and prevention. J Pediatrics 1992;121:503-510.
- Shay DK, Holman RC, Newman RD, Liu LL, Stout JW, Anderson LJ. Bronchiolitis-associated hospitalizations among U.S. children, 1980-1996 JAMA 1999;282:1440-1446.
- Heilman CA. Respiratory and parainfluenza viruses. Journal of Infectious Diseases 1990:161:403-406.
- Indian Health Service. Trends in Indian HealthB1995. Rockville, MD: U.S. Department of Health and Human Services, 1996.
- Karron RA, SingletonRJ, Bulkow LR, et al. Severe respiratory syncytial virus infection in Alaska Native children. J Infect Dis 1999;180:41-49.
- Bulkow LR, Singleton RJ, Karron RA, Harrison LH and the Alaska RSV Study Group. Risk factors for severe respiratory syncytial virus infection among Alaska Native children. Pediatrics 2002;109:210-216.
- Singleton R, Petersen K, Berner J et al. Hospitalizations for respiratory syncytial virus infection in Alaska Native children. Pediatr Infect Dis J 1995;14:26-30.
