Common cold

Colds, sometimes called rhinovirus or coronavirus infections, are the most common illness to strike any part of the body. It is estimated that the averageperson 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.

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 such as fatigue and overwork, emotional stress, and poor nutrition may lead to increased susceptibility.

Colds make the upper respiratory system less resistant to bacterial infection. Secondary bacterial infection may lead to 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.

Colds are caused by more than 200 different viruses. The most common groups are 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 infection. Colds pass from person to person in several ways. When an infected person coughs, sneezes, or speaks, tiny fluid droplets containing the virus areexpelled. If these are breathed in by other people, the virus may establishitself in their noses and airways.

Colds may also be passed through direct contact. If a person with a cold touches his runny nose or watery eyes, then shakes hands with another person someof 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 (doorknobs, telephones, toys) that become contaminated with the virus.

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 calledhistamine. Histamine increases the blood flow to the infected cells, causingswelling, congestion, and increased mucus production. Within one to three days the infected person begins to show cold symptoms.

The first cold symptoms are a tickle in the throat, runny nose, and sneezing.The initial discharge from the nose is clear and thin. Later it changes to athick yellow or greenish discharge. Most adults do not develop a fever whenthey catch a cold. Young children may develop a low fever of up to 102°F(38.9°C).

In addition to a runny nose and fever, signs of a cold include coughing, sneezing, nasal congestion, headache, muscle ache, chills, sore throat, hoarseness, watery eyes, tiredness, and lack of appetite. The cough that accompanies acold is usually intermittent and dry.

Colds make people more susceptible to bacterial infections such as strep throat, middle ear infections, and sinus infections. A person whose cold does notbegin to improve within a week; or who experiences chest pain, fever for more than a few days, difficulty breathing, bluish lips or fingernails, a coughthat brings up greenish-yellow or grayish sputum, skin rash, swollen glands,or whitish spots on the tonsils or throat should 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 ofmedications, (corticosteroids, chemotherapy drugs)--should consult their doctor if they get a cold. People with these health problems are more likely toget a secondary infection.

Colds are diagnosed by observing a person's symptoms. There are no laboratorytests readily available to detect the cold virus. However, a doctor may do athroat culture or blood test to rule out a secondary infection.

There are no medicines that will cure the common cold. Given time, the body'simmune system will make antibodies to fight the infection, and the cold willbe resolved without any intervention. Antibiotics are useless against a cold. However, a great deal of money is spent by pharmaceutical companies in theUnited States promoting products designed to relieve cold symptoms. These products usually contain antihistamines, decongestants, or pain relievers.

Given time, the body will make antibodies to cure itself of a cold. Most colds last a week to 10 days. Most people start feeling better within 4 or 5 days. Occasionally a cold will lead to a secondary bacterial infection which causes strep throat, bronchitis, pneumonia, sinus infection, or a middle ear infection. These conditions usually clear up rapidly when treated with an antibiotic.

It is not possible to prevent colds because the viruses that cause colds arecommon and highly infectious. However, using common sense can help to reducetheir spread, for example, eating a healthy diet and getting enough sleep, and avoiding close contact with someone who has a cold for the first few days of their infection.

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