Human rhinovirus A
Human rhinovirus B
Human rhinovirus C
Human rhinovirus (from the Greek rhin- which means "nose") are the most common viral infective agents in humans and are the cause of the common cold. Rhinovirus infection proliferates in temperatures between 33–35 °C, and this may be why reproduction occurs primarily in the nose. Rhinovirus is a species in the genus Enterovirus of the Picornaviridae family of viruses.
There are 99 recognized types of Human rhinoviruses that differ according to their surface proteins. They are lytic in nature and are among the smallest viruses, with diameters of about only 30 nanometers. Other viruses such as smallpox and vaccinia are around 10 times larger at about 300 nanometers.
Transmission and epidemiology
There are two modes of transmission: via aerosols of respiratory droplets and from contaminated surfaces, including direct person-to-person contact.
Human rhinoviruses occur worldwide and are the primary cause of common colds. Symptoms include sore throat, runny nose, nasal congestion, sneezing and cough; sometimes accompanied by muscle aches, fatigue, malaise, headache, muscle weakness, or loss of appetite. Fever and extreme exhaustion are more usual in influenza. Children may have six to twelve colds a year. In the United States, the incidence of colds is higher in the autumn and winter, with most infections occurring between September to April. The seasonality may be due to the start of the school year, or due to people spending more time indoors (thus in closer proximity with each other), increasing the chance of transmission of the virus.
The primary route of entry for Human rhinoviruses is the upper respiratory tract. Afterward, the virus binds to ICAM-1 (Inter-Cellular Adhesion Molecule 1) also known as CD54 (Cluster of Differentiation 54) receptors on respiratory epithelial cells. As the virus replicates and spreads, infected cells release distress signals known as chemokines and cytokines (which in turn activate inflammatory mediators).
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