Published on 22/03/2015 by admin
Filed under Pediatrics
Last modified 22/03/2015
This article have been viewed 884 times
Chapter 255 Rhinoviruses
E. Kathryn Miller, John V. Williams
Human rhinoviruses (HRVs) are the most frequent cause of the common cold in both adults and children. Although rhinoviruses were once thought to cause only the common cold, it is now known that they are associated with lower respiratory infections in adults and children. Many HRVs do not grow in culture; studies using molecular diagnostic tools such as polymerase chain reaction (PCR) have revealed that HRVs are leading causes of both mild and serious respiratory illnesses in children.
Human rhinoviruses are members of the Picornaviridae family (“pico” = small; “rna” = RNA genome). Traditional methods of virus typing using immune antiserum have identified ≈ 100 serotypes, classified into HRVA and HRVB species on the basis of genetic sequence similarity. A novel group of HRVs designated HRVC has been detected by reverse transcriptase PCR (RT-PCR) but has not yet been cultivated. Virus gene sequence analysis demonstrates that HRVC are a genetically distinct species. The increased proportions of HRV reported in recent PCR-based studies may partly be due to detection of these previously unknown HRVC viruses in addition to improved detection of known HRVA and HRVB strains.
Rhinoviruses are distributed worldwide, and there is no proven correlation between serotypes and epidemiologic or clinical characteristics. Multiple serotypes may circulate in a community simultaneously, and particular HRV strains may be isolated during consecutive epidemic seasons, suggesting persistence in a community over an extended period. In temperate climates the incidence of HRV infection peaks in fall, with another peak in spring, but HRV infections occur year-round. Rhinoviruses are the major infectious trigger for asthma among young children, and numerous studies have described a sharp increase in asthmatic attacks in this age group when school opens in the fall. Peak HRV incidence in the tropics occurs during the rainy season, from June to October.
Rhinoviruses are present in high concentrations in nasal secretions and can be detected in the lower airways. Rhinovirus particles are nonenveloped and quite hardy, persisting for several hours in secretions on hands or other surfaces such as telephones, light switches, doorknobs, and stethoscopes. Transmission occurs when infected secretions carried on contaminated fingers are rubbed onto nasal or conjunctival mucosa. Rhinoviruses are present in aerosols produced by talking, coughing, and sneezing. Children are the most important reservoir of the virus.
Nelson Textbook of Pediatrics Expert Consult
