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Jai Ganesh

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Registered: 2005-06-28

Posts: 48,384

Common Cold

Common Cold

Gist

Sneezing, stuffy and runny nose? You might have a cold. Colds are one of the most frequent reasons for missed school and work. Every year, adults have an average of 2 to 3 colds, and children have even more.

Antibiotics do not work against viruses that cause colds and will not help you feel better.

Summary

You can often treat a cold without seeing a GP. You should begin to feel better in about 1 to 2 weeks.

Check if you have a cold

Cold symptoms come on gradually and can include:

* a blocked or runny nose
* a sore throat
* headaches
* muscle aches
* coughs
* sneezing
* a raised temperature
* pressure in your ears and face
* loss of taste and smell

The symptoms are the same in adults and children. Sometimes symptoms last longer in children.

How you can treat a cold yourself

To help you get better more quickly:

* rest and sleep
* drink plenty of water (fruit juice or squash mixed with water is OK) to avoid dehydration
* gargle salt water to soothe a sore throat (not suitable for children)

If you have a high temperature or you do not feel well enough to do your normal activities, try to stay at home and avoid contact with other people until you feel better.

A pharmacist can help with cold medicines

You can buy cough and cold medicines from pharmacies or supermarkets. A pharmacist can advise you on the best medicine.

You can:

* ease aches or lower a temperature with painkillers like paracetamol or ibuprofen
* relieve a blocked nose with decongestant sprays or tablets

Decongestants should not be given to children under 6. Children aged 6 to 12 should take them for no longer than 5 days.

Be careful not to use cough and cold medicines if you're taking paracetamol and ibuprofen tablets. Cough and cold medicines often also contain paracetamol and ibuprofen so it can be easy to take more than the recommended dose.

Some are not suitable for children, babies and pregnant women.

There's little evidence that supplements (such as vitamin C, echinacea or garlic) prevent colds or speed up recovery.

See a GP if:

* your symptoms do not improve after 3 weeks
* your symptoms get suddenly worse
* your temperature is very high or you feel hot and shivery
* you're concerned about your child's symptoms
* you're feeling short of breath or develop chest pain
* you have a long-term medical condition – for example, diabetes, or a heart, lung or kidney condition
* you have a weakened immune system – for example, because you're having chemotherapy

Antibiotics

GPs do not recommend antibiotics for colds because they will not relieve your symptoms or speed up your recovery.

Antibiotics are only effective against bacterial infections, and colds are caused by viruses.

How to avoid spreading a cold

Colds are caused by viruses and easily spread to other people. You're infectious until all your symptoms have gone. This usually takes 1 to 2 weeks.

Colds are spread by germs from coughs and sneezes, which can live on hands and surfaces for 24 hours.

To reduce the risk of spreading a cold:

* wash your hands often with warm water and soap
* use tissues to trap germs when you cough or sneeze
* bin used tissues as quickly as possible

How to prevent catching a cold

A person with a cold can start spreading it from a few days before their symptoms begin until the symptoms have finished.

The best ways to avoid catching a cold are:

* washing your hands with warm water and soap
* not sharing towels or household items (like cups) with someone who has a cold
* not touching your eyes or nose in case you have come into contact with the virus – it can infect the body this way
* staying fit and healthy

The flu vaccine helps prevent flu but not colds.

Details

The common cold or the cold is a viral infectious disease of the upper respiratory tract that primarily affects the respiratory mucosa of the nose, throat, sinuses, and larynx. Signs and symptoms may appear fewer than two days after exposure to the virus. These may include coughing, sore throat, runny nose, sneezing, headache, and fever. People usually recover in seven to ten days, but some symptoms may last up to three weeks. Occasionally, those with other health problems may develop pneumonia.

Well over 200 virus strains are implicated in causing the common cold, with rhinoviruses, coronaviruses, adenoviruses and enteroviruses being the most common. They spread through the air during close contact with infected people or indirectly through contact with objects in the environment, followed by transfer to the mouth or nose. Risk factors include going to child care facilities, not sleeping well, and psychological stress. The symptoms are mostly due to the body's immune response to the infection rather than to tissue destruction by the viruses themselves. The symptoms of influenza are similar to those of a cold, although usually more severe and less likely to include a runny nose.

There is no vaccine for the common cold. The primary methods of prevention are hand washing; not touching the eyes, nose or mouth with unwashed hands; and staying away from sick people. Some evidence supports the use of face masks. There is also no cure, but the symptoms can be treated. Zinc may reduce the duration and severity of symptoms if started shortly after the onset of symptoms. Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen may help with pain. Antibiotics, however, should not be used, as all colds are caused by viruses, and there is no good evidence that cough medicines are effective.

The common cold is the most frequent infectious disease in humans. Under normal circumstances, the average adult gets two to three colds a year, while the average child may get six to eight. Infections occur more commonly during the winter. These infections have existed throughout human history.

Signs and symptoms

The typical symptoms of a cold include cough, runny nose, sneezing, nasal congestion, and a sore throat, sometimes accompanied by muscle ache, fatigue, headache, and loss of appetite. A sore throat is present in about 40% of cases, a cough in about 50%, and muscle ache likewise in about 50%. In adults, a fever is generally not present but it is common in infants and young children. The cough is usually mild compared to that accompanying influenza. While a cough and a fever indicate a higher likelihood of influenza in adults, a great deal of similarity exists between these two conditions. A number of the viruses that cause the common cold may also result in asymptomatic infections.

The color of the mucus or nasal secretion may vary from clear to yellow to green and does not indicate the class of agent causing the infection.

Progression

A cold usually begins with fatigue, a feeling of being chilled, sneezing, and a headache, followed in a couple of days by a runny nose and cough. Symptoms may begin within sixteen hours of exposure and typically peak two to four days after onset. They usually resolve in seven to ten days, but some can last for up to three weeks. The average duration of cough is eighteen days and in some cases people develop a post-viral cough which can linger after the infection is gone. In children, the cough lasts for more than ten days in 35–40% of cases and continues for more than 25 days in 10%.

Causes:

Viruses

The common cold is an infection of the upper respiratory tract which can be caused by many different viruses. The most commonly implicated is a rhinovirus (30–80%), a type of picornavirus with 99 known serotypes. Other commonly implicated viruses include human coronaviruses (≈ 15%), influenza viruses (10–15%), adenoviruses (5%), human respiratory syncytial virus (RSV), enteroviruses other than rhinoviruses, human parainfluenza viruses, and human metapneumovirus. Frequently more than one virus is present. In total, more than 200 viral types are associated with colds.

Transmission

The common cold virus is typically transmitted via airborne droplets (aerosols), direct contact with infected nasal secretions, or fomites (contaminated objects). Which of these routes is of primary importance has not been determined. The viruses may survive for prolonged periods in the environment (over 18 hours for rhinoviruses) and can be picked up by people's hands and subsequently carried to their eyes or nose where infection occurs. Transmission from animals is considered highly unlikely; an outbreak documented at a British scientific base on Adelaide Island after seventeen weeks of isolation was thought to have been caused by transmission from a contaminated object or an asymptomatic human carrier, rather than from the husky dogs which were also present at the base.

Transmission is common in daycare and at school due to the proximity of many children with little immunity and frequently poor hygiene. These infections are then brought home to other members of the family. There is no evidence that recirculated air during commercial flight is a method of transmission. People sitting close to each other appear to be at greater risk of infection.

Rhinovirus-caused colds are most infectious during the first three days of symptoms; they are much less infectious afterwards.

Weather

A common misconception is that one can "catch a cold" merely through prolonged exposure to cold weather. Although it is now known that colds are viral infections, the prevalence of many such viruses are indeed seasonal, occurring more frequently during cold weather. The reason for the seasonality has not been conclusively determined. Possible explanations may include cold temperature-induced changes in the respiratory system, decreased immune response, and low humidity causing an increase in viral transmission rates, perhaps due to dry air allowing small viral droplets to disperse farther and stay in the air longer.

The apparent seasonality may also be due to social factors, such as people spending more time indoors, near infected people, and specifically children at school. Although normal exposure to cold does not increase one's risk of infection, severe exposure leading to significant reduction of body temperature (hypothermia) may put one at a greater risk for the common cold; although controversial, the majority of evidence suggests that it may increase susceptibility to infection.

Other

Herd immunity, generated from previous exposure to cold viruses, plays an important role in limiting viral spread, as seen with younger populations that have greater rates of respiratory infections. Poor immune function is a risk factor for disease. Insufficient sleep and malnutrition have been associated with a greater risk of developing infection following rhinovirus exposure; this is believed to be due to their effects on immune function. Breast feeding decreases the risk of acute otitis media and lower respiratory tract infections among other diseases, and it is recommended that breast feeding be continued when an infant has a cold. In the developed world breast feeding may not be protective against the common cold in and of itself.

Pathophysiology

The symptoms of the common cold are believed to be primarily related to the immune response to the virus. The mechanism of this immune response is virus-specific. For example, the rhinovirus is typically acquired by direct contact; it binds to humans via ICAM-1 receptors and the CDHR3 receptor through unknown mechanisms to trigger the release of inflammatory mediators. These inflammatory mediators then produce the symptoms. It does not generally cause damage to the nasal epithelium. The respiratory syncytial virus (RSV), on the other hand, is contracted by direct contact and airborne droplets. It then replicates in the nose and throat before frequently spreading to the lower respiratory tract. RSV does cause epithelium damage. Human parainfluenza virus typically results in inflammation of the nose, throat, and bronchi. In young children, when it affects the trachea, it may produce the symptoms of croup, due to the small size of their airways.

Diagnosis

The distinction between viral upper respiratory tract infections is loosely based on the location of symptoms, with the common cold affecting primarily the nose (rhinitis), throat (pharyngitis), and lungs (bronchitis). There can be significant overlap, and more than one area can be affected. Self-diagnosis is frequent. Isolation of the viral agent involved is rarely performed, and it is generally not possible to identify the virus type through symptoms.

Prevention

The only useful ways to reduce the spread of cold viruses are physical measures such as using correct hand washing technique and face masks; in the healthcare environment, gowns and disposable gloves are also used. Isolation or quarantine is not used as the disease is so widespread and symptoms are non-specific. There is no vaccine to protect against the common cold. Vaccination has proven difficult as there are many viruses involved and they mutate rapidly. Creation of a broadly effective vaccine is, therefore, highly improbable.

Regular hand washing appears to be effective in reducing the transmission of cold viruses, especially among children. Whether the addition of antivirals or antibacterials to normal hand washing provides greater benefit is unknown. Wearing face masks when around people who are infected may be beneficial; however, there is insufficient evidence for maintaining a greater social distance.

It is unclear whether zinc supplements affect the likelihood of contracting a cold. Routine vitamin C supplements do not reduce the risk or severity of the common cold, though they may reduce its duration.

Additional Information

Common cold is an acute viral infection that starts in the upper respiratory tract, sometimes spreads to the lower respiratory structures, and may cause secondary infections in the eyes or middle ears. More than 200 agents can cause symptoms of the common cold, including parainfluenza, influenza, respiratory syncytial viruses, and reoviruses. Rhinoviruses, however, are the most frequent cause, and some 100 different strains of rhinoviruses have been associated with coldlike illness in humans.

The popular term common cold reflects the feeling of chilliness on exposure to a cold environment that is part of the onset of symptoms. The cold is caught from exposure to infected people. People can carry the virus and communicate it without experiencing any of the symptoms themselves. Incubation is short—usually one to four days. The viruses start spreading from an infected person before the symptoms appear, and the spread reaches its peak during the symptomatic phase. The incidence of colds peaks during the autumn, and minor epidemics commonly occur throughout the winter. The reason for this incidence is unknown; it may result from the greater amount of time spent indoors, which increases the likelihood of close contact with those persons carrying cold viruses. Young children can contract between three and eight colds a year; they usually come into contact with the infectious agents in day-care centres or preschools.

Cold symptoms vary from person to person, but in the individual the same symptoms tend to recur in succeeding bouts of infection. Symptoms may include sneezing, headaches, fatigue, chills, sore throat, inflammation of the nose (rhinitis), and nasal discharge. There is usually no fever. The nasal discharge is the first warning that one has caught a cold. Once a virus becomes established on the respiratory surface of the nose, its activities irritate the nose’s cells, which respond by pouring out streams of clear fluid. This fluid acts to dilute the virus and clear it from the nose. The sensory organs in the nose are stung by the inflammatory reaction, thereby setting up sneezing, a second method of expelling the virus. If the virus penetrates more deeply into the upper respiratory tract, coughing is added to the infected person’s symptoms in a further effort to get rid of the virus. Coughing can be dry or produce amounts of mucus. Symptoms abate as the host’s defenses increase, the clear fluid often changing to a thick, yellow-green fluid that is full of the debris of dead cells. The usual duration of the illness is about five to seven days, but lingering cough and postnasal discharge may persist for two weeks or more.

Diagnosis of a cold is usually made by medical history alone, although it is possible to take a culture for viruses. There is no effective antiviral agent available for the common cold. Therapy consists of treating the symptoms—relieving aches, fever, and nasal congestion. One of the greatest medical controversies in the past few decades concerned the efficacy of vitamin C (ascorbic acid) in the prevention or treatment of the common cold. In many studies, administration of ascorbic acid failed to prevent or decrease the symptoms of the common cold.

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