It is estimated that infants who develop a wheeze as a result of RSV contraction develop a recurring wheeze in around two thirds of all cases. It is also estimated that around half of these children will develop some form of asthma (Lehtinen et al., 2007). It is unclear why there are some who experience delayed onset of RSV, although both immune 'imprinting' and viral persistence have been implicated (Openshaw and Tregoning, 2005). Diagnosis

The condition is diagnosed through rapid antigen-detection tests. It is difficult to diagnose RSV in adults as the tests are insensitive in persons other than children, and practitioners rarely request tests for RSV in adults. This means that it is difficult to differentiate between influenza and RSV in adults. It has been suggested that a certain amount of deaths which have been attributed to influenza in adults may actually be a result of RSV (Thompson et al., 2003).

Although this is the most popular method for diagnosis there is also the possibility of using virus isolation, detection of viral RNA, serum antibody detection, or a combination of approaches in order to diagnose RSV. The techniques require either the collection of a sample from nasal drainage or a blood sample. The use of blood samples is more reliable in adults than in children, as there is the possibility that infants' blood may remain contaminated by their mother's blood. There may be a need to perform other tests on a child's blood however as blood gas analysis may be necessary to ensure that the child is receiving enough oxygen. There is often no need to perform diagnostic tests to confirm the diagnosis of RSV as the symptoms and clinical history often allow a diagnosis to be made with enough certainty to begin treatment (Health-Cares.net, 2005).

Treatment

Treatment usually focuses on relief of the symptoms associated with RSV. This would usually involve medications such as acetaminophen to reduce fever and fluids to prevent dehydration. If the symptoms are more severe and lead to complications in the respiratory system there may be a need for oxygen therapy and occasionally mechanical ventilation. The most common symptomatic treatments which are used in treating bronchiolitis and asthma resulting from RSV infection are similar to other asthma treatments. These include bronchodilators and corticosteroids. A systematic review of the available treatment options in 2004 suggested that there was very little long-term improvement using the treatments currently available. This suggests that there is a need for the development of new medications to be used in the treatment of RSV-induced conditions (King et al., 2004).

Ribavirin is also indicated in the treatment of patients with severe symptoms (CDC, 2005). Ribavirin is an antiviral agent which is designed to act specifically on the RS virus (King et al., 2004). There are specific treatments which are indicated in the treatment of those who contract RSV when they are immunocompromised. This includes treatment with aerosolized ribivarin and also immunoglobulin products, which are aimed at replicating the natural immune system responses to the virus. There have been disagreements relating to the effectiveness of ribavirin treatment in immunocompromised patients. The use of the combination of therapies is however the current standard care for treatment of RSV in immunocompromised patients, which is expected to compensate should the ribavirin prove to not be effective in any patient (Flynn et al., 2004).

Recent research has shown that clarithromycin is effective in the treatment of RSV-induced bronchiolitis. A randomized, double-blind, placebo-controlled clinical trial in 21 infants showed that the use of clarithromycin resulted in clinically significant reductions in length of stay in hospital. The clarithromycin use also resulted in a decrease in the need for oxygen supplementation and there was a decrease in the number of re-admissions which occurred over a six-month period in the group which received clarithromycin (Tahan et al., 2007).

It is typical for around 70% of children to recover from RSV unaffected in the long-term, although this number is reduced as the age of the child increases (Jartti et al., 2004). Those who do recover are still left prone to recurrent periods of wheezing and asthma later in life,...

It is so far unknown whether this relationship is causal (Openshaw, 2005).
Prevention

There is currently no vaccine available to guard against RSV infection. The predominant method of RSV prevention is currently thorough infection control procedures. The vulnerability of the virus to soap and water or disinfectant means that thorough cleaning of anything which may become infected, along with good hand washing practices, should prevent cross-contamination (CDC, 2005).

There have recently been some advances toward drug-based prophylaxis for prevention of RSV. The lack of an effective vaccine has meant that developments have focused on passive immunotherapy strategies in those children considered to be at risk of RSV contraction.

There are two medications which are currently FDA approved for prevention of RSV in children who are considered to be at high risk. Both of the medications provide RSV-neutralizing antibody to those taking the medication. The first goes by the commercial name RespiGam, which was licensed in 1996. This is a form of immunoglobulin G, which contains high titers of antibody against RSV. The second is palivizumab, which is possibly the most common treatment. This is a humanized murine monoclonal antibody which targets the F. glycoprotein in the RSV envelope. In phase III clinical trials palivizumab was shown to significantly reduce hospitalization associated with RSV-induced conditions (Feltes and Sondheimer, 2006). Both of these medications have been approved for some time in prophylaxis, although neither is approved for treatment of the virus. Neither drug is approved for use in those with congenital heart disease, which means that any child which is considered at risk of RSV with that condition has no option for prophylaxis at the current time.

References

Centers for Disease Control and Prevention (2005) Respiratory Syncytial Virus. National Center for Infectious Diseases: Respiratory and Enteric Viruses Branch. Retrieved on November 11, 2007, at http://www.cdc.gov/ncidod/dvrd/revb/respiratory/rsvfeat.htm.

Feltes, T.F. And Sondheimer, H.M. (2006) Palivizumab and the prevention of respiratory syncytial virus illness in pediatric patients with congenital heart disease. Expert Opinion on Biological Therapy, 7(9): 1471-1480.

Flynn, J.D., Akers, W.S., Jones, M., Stevkovic, N., Waid, T., Mullett, T. And Jahania, S. (2004) Treatment of Respiratory Syncytial Virus pneumonia in a lung transplant recipient: Case report and review of literature. Pharmacotherapy. Retrieved on November 11, 2007, at http://www.medscape.com/viewarticle/482817?src=mp.

Health-Cares.net (2005) "How is RSV infection diagnosed?" Retrieved on November 11, 2007, at http://respiratory-lung.health-cares.net/rsv-infection-diagnosis.php.

King, V.J., Viswanathan, M., Bordley, W.C., Jackman, a.M., Sutton, S.F., Lohr, K.N. And Carey, T.S. (2004) Pharmacologic treatment of bronchiolitis in infants and children. Archives of Pediatric Adolescent Medicine, 158(2): 127-137.

Lehtinen, P., Ruohola, a., Vanto, T. et al. (2007) Analysis of steroid treatment of first wheezing episode. AAP Grand Rounds, 18: 6-7.

Jartti, T., Lehtinen, P., Vuorinen, T., Osterback, R., van den Hoogen, B., Osterhaus, a.D.M.E. And Russkanen, O. (2004) Respiratory picornaviruses and respiratory syncytial virus as causative agents of acute expiratory wheezing in children. Emerging Infectious Diseases, 10(6): 1095-1101.

Openshaw, P.J.M. (2005) Antiviral immune responses and lung inflammation after Respiratory Syncytial Virus infection. The Proceedings of the American Thoracic Society, 2: 121-125.

Openshaw, P.J.M. And Tregoning, J.S. (2005) Immune response and disease enhancement during Respiratory Syncytial Virus infection. Clinical Microbiology Reviews, 18(3): 541-555.

Tahan, F., Ozcan, a. And Koc, N. (2007) Clarithromycin in the treatment of RSV bronchiolitis: A double-blind, randomized, placebo-controlled trial. European Respiratory Journal, 29: 91-97.

Thompson, W.W., Shay, D.K., Weintraub, E., Brammer, L., Cox, N., Anderson, L.J. And Fukuda, K. (2003) Mortality associated with influenza and Respiratory Syncytial Virus in the United States. JAMA, 289: 179-186.