Human respiratory syncytial virus Questions With Complete Solutions.

Human respiratory syncytial virus - is a syncytial virus that causes respiratory tract infections. It is a major cause of lower respiratory tract infections and hospital visits during infancy and childhood. A prophylactic medication (not a vaccine) exists for preterm (under 35 weeks gestation) infants, infants with certain congenital heart defects (CHD) or bronchopulmonary dysplasia (BPD), and infants with congenital malformations of the airway. Treatment is limited to supportive care (e.g. C-PAP), including oxygen therapy. Signs and symptoms - The incubation time (from infection until symptoms arrive) is 4-5 days. For adults, RSV produces mainly mild symptoms, often indistinguishable from common colds and minor illnesses. The Centers for Disease Control consider RSV to be the "most common cause of bronchiolitis (inflammation of the small airways in the lung) and pneumonia in children under 1 year of age in the United States".[3] For some children, RSV can cause bronchiolitis, leading to severe respiratory illness requiring hospitalization and, rarely, causing death. This is more likely to occur in patients that are immunocompromised or infants born prematurely. Other RSV symptoms common among infants include listlessness, poor or diminished appetite, and a possible fever. Recurrent wheezing and asthma are more common among individuals who suffered severe RSV infection during the first few months of life than among controls;[4] whether RSV infection sets up a process that leads to recurrent wheezing or whether those already predisposed to asthma are more likely to become severely ill with RSV has yet to be determined. Symptoms of pneumonia in immuno-compromised patients such as in transplant patients and especially bone marrow transplant patients should be evaluated to rule out RSV infection. This can be done by means of polymerase chain reaction (PCR) testing for RSV nucleic acids in peripheral blood samples if all other infectious processes have been ruled out or if it is highly suspicious for RSV such as a recent exposure to a known source of RSV infection. In one case, RSV onset appears to have coincided with the onset of type 2 diabetes.[ Complications - bronchiolitis or pneumonia asthma recurring infections acute otitis mediaDiagnosis - Respiratory syncytial virus may be suspected based on the time of year of the infection; prevalence usually coincides with the winter flu season. physical exam: wheezing and other abnormal sounds in the chest Chest X-rays to check for typical bilateral perihilar fullness of bronchiolitis induced by the virus skin monitoring to check for hypoxemia, a lower than usual level of oxygen in the bloodstream Blood tests to check white cell counts or to look for the presence of viruses, bacteria or other organisms lab test of respiratory secretions Several different types of laboratory tests are commercially available for diagnosis of RSV infection. Rapid diagnostic assays performed on respiratory specimens are available commercially. Most clinical laboratories currently utilize antigen detection tests. Compared with culture, the sensitivity of antigen detection tests generally ranges from 80% to 90%. Antigen detection tests and culture are generally reliable in young children but less useful in older children and adults. Sensitivity of virus isolation from respiratory secretions in cell culture varies among laboratories. RT-PCR assays are now commercially available. The sensitivity of these assays is equal to or exceeds the sensitivity of virus isolation and antigen detections methods. Highly sensitive RT-PCR assays should be considered when testing adults, because they may have low viral loads in their respiratory specimens. Serologic tests are less frequently used for diagnosis. Although useful for research, a diagnosis using a collection of paired acute and convalescent sera to demonstrate a significant rise in antibody titer to RSV can not be made in time to guide care of the patient. On top of that, the antibody level does not always correlate with the acuteness or activity level of the infection. RSV infection can be confirmed using tests for antigens or antibodies, or viral RNA by reverse transcription PCR. Quantification of viral load can be determined by various assay tests. Treatment - To date, treatment has been limited to supportive measures. Adrenaline, bronchodilators, steroids, antibiotics, and ribavirin confer "no real benefit".[13][14]