common cold(redirected from Coryzal illness)
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cold, common, acute viral infection of the mucous membranes of the nose and throat, often involving the sinuses. The typical sore throat, sneezing, and fatigue may be accompanied by body aches, headache, low fever, and chills. The congested and discharging mucous membrane may become a fertile ground for a secondary bacterial invasion that can spread to the larynx, bronchi, lungs, or ears. Uncomplicated infections usually last from three to ten days.
The cold is the most common human ailment. Most adult Americans suffer from one to four colds per year, but children ages one to five—who are the most susceptible—typically may contract as many as eight. Colds are spread by respiratory droplets or by contaminated hands or objects. Although the incidence of colds is higher in winter, exposure to chilling or dampness is considered to be of little significance.
Any one of up to 200 viruses (such as the rhinoviruses, coronaviruses, or respiratory syncytial virus [RSV]) can cause colds, to which it seems almost no one is immune. Infection with a viral strain confers only temporary immunity to that strain. Colds in infants and young children caused by RSV can progress to pneumonia and other complications, especially in those under a year old who were born prematurely or have chronic lung disease; RSV causes an estimated 4,500 deaths yearly in these groups in the United States.
Treatment for the common cold aims at relieving symptoms and keeping the body well-rested, -fed, and -hydrated. Because of the growing problem of drug resistance, doctors are discouraged from prescribing antibiotics (which do not affect viruses) for colds unless secondary bacterial infection makes them necessary. There is some evidence that zinc preparations, when taken within 24 hours of the first cold symptoms, can shorten the duration and moderate the symptoms of an infection, but there is no convincing evidence that vitamin C megadoses can prevent the common cold.
Researchers have reported reduction or prevention of cold symptoms in human tests of an experimental drug against rhinoviruses, which cause nearly half of all colds. The drug acts by imitating a molecule in the body called ICAM-1, to which the rhinovirus attaches to produce colds. As rhinoviruses attach to the decoy molecules instead, the likelihood or severity of infection is decreased.
An acute infectious disorder characterized by nasal obstruction and discharge that may be accompanied by sneezing, sore throat, headache, malaise, cough, and fever. The disorder involves all human populations, age groups, and geographic regions; it is more common in winter than in summer in temperate climates. Most people in the United States experience at least one disabling cold (causing loss of time from work or school or a physician visit) per year. Frequencies are highest in children and are reduced with increasing age.
Most, or possibly all, infectious colds are caused by viruses. More than 200 different viruses can induce the illness, but rhinoviruses, in the picornavirus family, are predominant. Rhinoviruses are small ribonucleic acid-containing viruses with properties similar to polioviruses. Other viruses commonly causing colds include corona, parainfluenza, influenza, respiratory syncytial, entero, and adeno. See Adenoviridae, Rhinovirus
Cold viruses are spread from one person to another in either of two ways: by inhalation of infectious aerosols produced by the sneezing or coughing of ill individuals, or by inoculation with virus-containing secretions through direct contact with a person or a contaminated surface. Controlled experiments have not shown that chilling produces or increases susceptibility to colds. Infection in the nasopharynx induces symptoms, with the severity of the illness relating directly to the extent of the infection. Recovery after a few days of symptoms is likely, but some individuals may develop a complicating secondary bacterial infection of the sinuses, ear, or lung (pneumonia).
Colds are treated with medications designed to suppress major symptoms until natural defense mechanisms terminate the infection. Immunity to reinfection follows recovery and is most effective in relation to antibody in respiratory secretions. There is no established method for prevention of colds; however, personal hygiene is recommended to reduce contamination of environmental air and surfaces with virus that may be in respiratory secretions. See Pneumonia