Rhinovirus is a widespread respiratory virus recognized as the primary cause of the common cold. It is highly prevalent globally, affecting millions of individuals each year. While typically inducing mild illness for most, its commonality means it significantly contributes to missed school days and work absences.
Rhinovirus: Types and Structure
Rhinoviruses belong to the Picornaviridae family and are non-enveloped, positive-sense, single-stranded RNA viruses. There are at least 165 recognized types of rhinovirus, categorized into three distinct species: A, B, and C. This extensive genetic diversity complicates the development of universal vaccines or antiviral treatments.
These viruses are among the smallest known, measuring approximately 30 nanometers in diameter. Their structure consists of an icosahedral protein capsid, which encases the RNA genome. This capsid is composed of 60 copies of four viral proteins: VP1, VP2, VP3, and VP4. The VP1 protein is particularly important for attaching to host cells. Rhinoviruses show a preference for cooler temperatures, which explains their primary infection of the upper respiratory tract.
How Rhinovirus Spreads
Rhinovirus is highly contagious and spreads through multiple pathways. One common mode of transmission is through respiratory droplets released when an infected person coughs or sneezes. These larger droplets can travel a short distance through the air and be inhaled by others. The virus can also spread via aerosols, which are tiny airborne particles that remain suspended in the air for longer periods.
Contaminated surfaces, known as fomites, also play a role in transmission. Rhinoviruses can survive on surfaces like stainless steel or plastic for several hours. Direct person-to-person contact, such as shaking hands, can also facilitate the spread of the virus if individuals then touch their eyes, nose, or mouth. The primary entry points for rhinovirus are the mouth and nose.
Symptoms and Potential Complications
Rhinovirus infection typically results in symptoms commonly associated with the cold. These include a sore throat, runny nose, nasal congestion, sneezing, and coughing. Other possible symptoms are headache, mild body aches, and sometimes a low-grade fever. These symptoms often last less than 7 days for most individuals, though they can persist for up to two weeks.
While generally self-limiting, rhinovirus can lead to more severe outcomes, particularly in vulnerable populations. It is a recognized trigger for asthma attacks and can exacerbate reactive airway disease, causing wheezing and breathing difficulties. The virus can also contribute to middle ear infections (otitis media) and sinus infections (sinusitis).
In infants, the elderly, and immunocompromised individuals, rhinovirus infections can progress to more serious respiratory illnesses. This includes bronchiolitis, an infection of the small airways in the lungs, and bronchitis, which involves inflammation of the large airways. In severe cases, rhinovirus can cause pneumonia, a lung infection.
Prevention and Management
Preventing rhinovirus infection involves several practical strategies aimed at reducing exposure and spread. Frequent handwashing with soap and water is an effective measure to remove the virus from hands. Avoiding touching the face, especially the mouth, eyes, and nose, helps prevent the virus from entering the body. Covering coughs and sneezes with a tissue or into the upper sleeve can also limit the release of respiratory droplets.
There is currently no specific antiviral treatment or vaccine available for rhinovirus infections due to the large number of serotypes. Management focuses on supportive care to alleviate symptoms. This includes getting adequate rest and staying hydrated with fluids like water, herbal teas, or broths. Over-the-counter medications such as pain relievers like acetaminophen or ibuprofen can help reduce fever, headaches, and body aches. Decongestants and antihistamines may also be used to relieve nasal congestion, runny nose, and sneezing.