Definition
The common cold is a viral infection of the upper respiratory system, which includes the nose, throat, sinuses, eustachian tubes, trachea, larynx, and bronchial tubes. Although more than 200 different viruses can cause a cold, 30–50% are caused by a group known as rhinoviruses. Almost all colds clear up in less than two weeks without complications.
Description
Colds, sometimes called rhinovirus or coronavirus infections , are the most common illness to strike any part of the body. It is estimated that the average person has more than 50 colds during a lifetime. Anyone can get a cold, although preschool and grade school children catch them more frequently than adolescents and adults. Repeated exposure to viruses causing colds creates partial immunity.
Although most colds resolve on their own without complications, they are a leading cause of visits to the doctor and of time lost from work and school. Treating symptoms of the common cold has given rise to a multimillion dollar industry in over-the-counter medications, yet none of these medications are actually anti-viral to the rhinovirus.
Cold season in the United States begins in early autumn and extends through early spring. Although it is not true that getting wet or being in a draft causes a cold (a person has to come in contact with the virus to catch a cold), certain conditions may lead to increased susceptibility. These include:
fatigue and overwork
emotional stress
poor nutrition
smoking
inadequate rest or sleep
living or working in crowded conditions
Colds make the upper respiratory system less resistant to secondary bacterial infection. Secondary bacterial infection may lead to a number of other complications, including middle ear infection, bronchitis, pneumonia, sinus infection , or strep throat . People with chronic lung disease, asthma , diabetes, or a weakened immune system are more likely to develop these complications.
Causes & symptoms
Colds are caused by more than 200 different viruses. The most common groups include rhinoviruses and coronaviruses. Different groups of viruses are more infectious at different seasons of the year, but knowing the exact virus causing the cold is not important in treatment.
People with colds are contagious during the first two to four days of the onset of symptoms. Colds pass from person to person in several ways. When an infected person coughs, sneezes, or speaks, tiny fluid droplets containing the virus are expelled. If these are breathed in by other people, the virus may establish itself in their noses and airways.
Colds may also be passed through direct contact. For example, if a person with a cold touches his runny nose or watery eyes, then shakes hands with another person, some of the virus is transferred to the uninfected person. If that person then touches his mouth, nose, or eyes, the virus is transferred to an environment where it can reproduce and cause a cold.
Finally, cold viruses can be spread through inanimate objects (door knobs, telephones, toys) that become contaminated with the virus. This is a common method of transmission in child care centers. Another vector of transmission is air travel, due to closed air circulation in buildings.
Once acquired, the cold virus attaches itself to the lining of the nasal passages and sinuses. This causes the infected cells to release a chemical called histamine. Histamine increases the blood flow to the infected cells, causing swelling, congestion, and increased mucus production. Within one to three days, the infected person begins to show cold symptoms.
The first cold symptoms are usually a tickle in the throat, runny nose, and sneezing . The initial discharge from the nose is clear and thin. Later, it may change to a thick yellow or greenish discharge. Most adults do not develop a fever when they catch a cold. Young children may develop a low fever of up to 102°F (38.9°C).
Other symptoms of a cold include coughing, sneezing, nasal congestion, headache , muscle ache, chills, sore throat , hoarseness, watery eyes, fatigue, dull hearing and blocked eustachian tube (a danger when flying), and lack of appetite. The cough that accompanies a cold is usually intermittent and dry.
Most people begin to feel better four to five days after their cold symptoms become noticeable. All symptoms are generally gone within 10 days, except for a dry cough that may linger for up to three weeks.
Colds make people more susceptible to secondary bacterial infections such as strep throat, middle ear infections, and sinus infections. A person should seek a doctor's consultation if the cold does not begin to improve within a week. If an individual experiences chest pain , fever for more than a few days, difficulty breathing, bluish lips or fingernails, a cough that brings up greenish-yellow or grayish sputum, skin rash, swollen glands, or whitish spots on the tonsils or throat, then that person should also consult a doctor to see if they have acquired a secondary bacterial infection that needs to be treated with an antibiotic.
People who have emphysema , chronic lung disease, diabetes, or a weakened immune system—either from diseases such as AIDS or leukemia , or as the result of medications, (corticosteroids, chemotherapy drugs)—should consult their doctor if they get a cold. People with these health problems are more likely to get a secondary infection.
Diagnosis