The common cold , also known only as cold , is a viral infection of the upper respiratory tract that primarily affects the nose. Throat, sinus, and larynx may also be affected. Signs and symptoms may appear less than two days after exposure to the virus. These may include cough, sore throat, runny nose, sneezing, headache, and fever. People usually recover within seven to ten days, but some symptoms may last up to three weeks. Sometimes those with other health problems can develop pneumonia.
More than 200 virus strains are involved in causing the common cold, with rhinovirus being the most common. They spread by air during close contact with an infected person or indirectly through contact with objects in the environment, followed by transfer to the mouth or nose. Risk factors include going to daycare, not sleeping well, and psychological stress. The symptoms are mostly caused by the immune response to infection rather than tissue damage by the virus itself. Conversely, those affected by influenza can show the same symptoms as people with colds, but symptoms are usually more severe. In addition, influenza tends to produce colds.
There is no vaccine for common colds. The main preventive methods are: hand washing; not touching eyes, nose or mouth with unwashed hands; and stay away from the sick. Some evidence supports the use of face masks. Also there is no cure, but the symptoms can be treated. Zinc can reduce the duration and severity of symptoms if started immediately after onset of symptoms. Non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen can help with pain. Antibiotics, however, should not be used and there is no evidence for cough medicine.
Common flu is the most common contagious disease in humans. The average adult gets two to three colds each year, while the average child gets six to eight. Infection is more common during the winter. This infection has existed throughout human history.
Video Common cold
Signs and symptoms
Common symptoms of cold include cough, runny nose, stuffy nose and sore throat, sometimes accompanied by muscle pain, fatigue, headache, and loss of appetite. Sore throat occurs in about 40% of cases and coughs about 50%, while muscle pain occurs in about half. In adults, fever is generally absent but is common in infants and young children. The cough is usually mild compared to the influenza that accompanies it. While cough and fever show a higher likelihood of influenza in adults, many similarities exist between these two conditions. A number of viruses that cause common colds can also cause asymptomatic infections.
The color of sputum or nose secretions can vary from clear to yellow to green and does not indicate the agent class that causes the infection.
Progression
Colding usually begins with fatigue, a feeling of cold, sneezing, and headache, followed in a few days by colds and coughs. Symptoms can be started within sixteen hours of exposure and usually reach two to four days after onset. They usually heal in seven to ten days, but some can last up to three weeks. The average duration of cough is eighteen days and in some cases people develop a post-viral cough that can linger after infection is lost. In children, cough lasts for more than ten days in 35-40% of cases and continues for more than 25 days in 10%.
Maps Common cold
Cause
Virus
Common flu is a viral infection of the upper respiratory tract. The most commonly involved virus is rhinovirus (30-80%), a type of picornavirus with 99 known serotypes. Other frequent viruses include human corona virus (15%), influenza virus (10-15%), adenovirus (5%), syncytial human respiratory virus, enterovirus in addition to rhinovirus, human parainfluenza virus, and metapneumovirus. Often more than one virus is present. In total more than 200 types of viruses are associated with colds.
Transmission
Common flu viruses are usually transmitted through air droplets (aerosols), direct contact with infected nasal secretions, or fomites (contaminated objects). Which of these most important routes is yet to be determined. Viruses can survive for prolonged periods in the environment (more than 18 hours for rhinovirus) and can be taken by the hands of people and then taken to the eye or nose where the infection occurs. Transmission is common in daycare centers and in schools because of the proximity of many children with minimal immunity and often poor hygiene. This infection is then taken home to other family members. There is no evidence that air recirculated during commercial flights is a method of transmission. People sitting nearby seem to be at greater risk of getting infected.
Colds caused by Rhinovirus are most infectious during the first three days of symptoms; they are much less after the infection.
Weather
The traditional theory is that colds can be "caught" by prolonged exposure to cold weather like rain or winter conditions, which is how the disease got its name. Some viruses that cause regular flu are seasonal, occur more frequently during cold or wet weather. Seasonal reasons are not specified. Possible explanations include changes in cold temperatures in the respiratory system, decreased immune response, and low humidity leads to an increase in the rate of transmission of the virus, possibly because of the dry air that allows small droplets of the virus to spread further and stay in the air longer.
A clear seasonal season may also be due to social factors, such as people spending more time indoors, near infected people, and especially children in school. There is some controversy about the role of low body temperature as a risk factor for the common cold; Most evidence suggests that it may lead to greater susceptibility to infection.
More
The herd immunity, generated from previous exposure to the flu virus, plays an important role in limiting the spread of the virus, as seen in younger populations that have higher rates of respiratory infections. Poor immune function is a risk factor for the disease. Lack of sleep and malnutrition have been associated with a greater risk of infection following rhinovirus exposure; this is believed to be due to its effect on immune function. Breastfeeding reduces the risk of acute otitis media and lower respiratory tract infections among other diseases, and it is recommended that breastfeeding be continued when the baby is exposed to a cold. In developed countries, breastfeeding may not protect against the common cold itself.
Pathophysiology
Common flu symptoms are believed to be primarily related to the immune response to the virus. The mechanism of this immune response is virus-specific. For example, rhinoviruses are usually obtained by direct contact; it binds humans through ICAM-1 receptors and CDHR3 receptors through an unknown mechanism to trigger the release of inflammatory mediators. This inflammatory mediator then produces symptoms. This generally does not cause damage to the nasal epithelium. The syncytial respiratory virus (RSV), on the other hand, is contracted by direct contact and air droplets. Then replicate in the nose and throat before it often spreads to the lower respiratory tract. RSV causes epithelial damage. The human parainfluenza virus usually causes inflammation of the nose, throat, and bronchi. In young children when it affects the trachea it can produce the croup symptoms due to the small size of their airways.
Diagnosis
The difference between viral upper respiratory tract infections is loosely based on the location of symptoms with the common cold that primarily affects the nose, pharyngitis (throat), and bronchitis (lung). However, significant overlap may occur and some areas may be affected. Common flu is often defined as inflammation of the nose with varying amounts of throat inflammation. Self-diagnosis is common. Isolation of involved viral agents is rare, and it is generally not possible to identify the type of virus through symptoms.
Prevention
The only useful ways to reduce the spread of cold viruses are physical actions such as hand washing and face masks; in health care environments, disposable dress and gloves are also used. Isolation or quarantine is not used because the disease is widespread and the symptoms are not specific. Vaccinations have proved difficult because there are many viruses involved and they mutate quickly. The creation of highly effective vaccines is, therefore, highly unlikely.
Regular hand washing seems to be effective in reducing flu virus transmission, especially among children. Whether the addition of antiviral or antibacterial to normal hand washing gives greater benefit is unknown. Wearing a face mask while around an infected person may be beneficial; However, there is insufficient evidence to maintain a greater social distance.
It is unclear whether zinc supplements affect the chances of catching a cold. Regular vitamin C supplements do not reduce the risk or severity of common colds, although they can reduce their duration. Gargling with water was found useful in one small experiment.
Management
Treatment for the common cold mainly involves drugs and other therapies to relieve symptoms. Getting plenty of rest, drinking fluids to keep hydration, and gargling with warm salt water is a reasonable conservative step. Most of the benefits of symptomatic treatment are, however, associated with a placebo effect. No drugs or herbs are convincingly shown to shorten the duration of infection.
Symptomatic
Treatments that can help with symptoms include simple pain medications and medications for fevers such as ibuprofen and acetaminophen (paracetamol). However, it is unclear whether acetaminophen helps to overcome symptoms. It is not known whether over the counter cough medicine is effective for treating acute cough. Cough medicine is not recommended for use in children due to lack of evidence that supports the effectiveness and potential hazards. In 2009, Canada restricted the use of over-the-counter cough and cold medicines in children aged six and under due to concerns about unproven risks and benefits. Abuse of dextromethorphan (over-the-counter cough medicine) has caused a ban in some countries. Intranasal corticosteroids have not been found to be useful.
In adults short-term use of nasal decongestants may have little benefit. Antihistamines can improve symptoms on the first or second day; However, there is no long-term benefit and they have a bad effect such as drowsiness. Other decongestants such as pseudoephedrine appear effective in adults. Ipratropium nasal spray can reduce the symptoms of nasal nose but has little effect on nasal congestion. The safety and effectiveness of decongestant use of nose in children is unclear.
Due to a lack of research, it is not known whether increased fluid intake improves symptoms or shortens respiratory illness, and there is a lack of similar data for the use of heated moist air. One study has found rubbing the chest to provide some relief from night cough, congestion, and difficulty sleeping.
Exercise
Some suggest to avoid physical exercise if there are symptoms such as fever, spreading muscle pain or fatigue. It is considered safe to exercise moderately if symptoms are limited to the head, including runny nose, nasal congestion, sneezing, or a mild sore throat.
Antibiotics have no effect on viral infections or against viruses that cause common colds. Due to its side effects, antibiotics cause overall harm but are still commonly prescribed. Some of the reasons that antibiotics are so commonly prescribed include people's expectations for them, the doctor's willingness to help, and the difficulty in ruling out complications that may be antibiotic-bearing. There is no effective antiviral drug for common colds although some preliminary studies have shown benefit.
Alternative medicine
Although there are many alternative treatments that are used for common colds, there is not enough scientific evidence to support most usage. In 2014 there is no sufficient evidence to recommend or oppose honey. In 2015 there is temporary evidence to support nasal irrigation.
Zinc supplements can shorten the duration and reduce the severity of symptoms if supplementation begins within 24 hours after onset of symptoms. Some of the zinc treatment directly applied to the inside of the nose has caused the loss of the sense of smell.
The effects of vitamin C on common colds, when examined extensively, are disappointing, except in limited circumstances: in particular, individuals who exercise hard in cold environments. There is no solid evidence that Echinacea products provide significant benefits in treating or preventing colds. It is not known whether garlic is effective. One vitamin D trial found no benefit.
Prognosis
Common flu is generally mild and self-limiting with most of the symptoms generally getting better within a week. Half of cases disappear within 10 days and 90% within 15 days. Severe complications, if they occur, are usually in very old, very young, or those who are immunosuppressed. Secondary bacterial infection can occur which results in sinusitis, pharyngitis, or ear infections. It is estimated that sinusitis occurs in 8% and ear infections in 30% of cases.
Epidemiology
Common flu is the most common human disease affecting people around the world. Adults typically have two to three infections each year, and children may have six to ten colds per year (and up to twelve colds per year for schoolchildren). The rate of symptomatic infection increases in the elderly because of decreased immunity.
Native Americans and Inuit are more likely to get colds and develop complications such as otitis media than Caucasians. This can be explained by issues such as poverty and density rather than by ethnicity.
History
While the common causes of the flu have only been identified since the 1950s, the disease has been with humans throughout history. The symptoms and treatment are described in Egyptian Ebers papyrus, the oldest medical texts available, written before the 16th century BC. The name "cold" began to be used in the 16th century, because of the similarity between symptoms and cold weather exposure.
In the UK, the Cold Cold Unit was established by the Medical Research Council in 1946 and where rhinovirus was discovered in 1956. In 1970, the CCU demonstrated that treatment with interferon during the incubation phase of rhinovirus infection protects slightly against the disease, but no practical treatment can developed. The unit was closed in 1989, two years after completing the lozenges zinc gluconate study in prophylaxis and rhinovirus flu treatment, the only successful treatment in the history of the unit.
Society and culture
The economic impact of the common cold is not well understood in most parts of the world. In the United States, the common cold causes 75-100 million doctor visits each year with a conservative cost estimate of $ 7.7 billion per year. Americans spend $ 2.9 billion on over-the-counter medicines and another $ 400 million for prescription drugs to relieve symptoms. More than a third of people who see doctors receive antibiotic prescriptions, which have implications for antibiotic resistance. An estimated 22-189 million school days are missed each year due to a fever. As a result, parents spend 126 million working days to stay home to care for their children. When added to the 150 million working days spent by employees suffering from flu, the total economic impact of cold-related job losses exceeds $ 20 billion per year. It accounts for 40% of the time lost from employment in the United States.
Direction of research
Antiviral has been tested for effectiveness in common colds; in 2009, nothing was found to be effective and licensed for use. There is an ongoing trial of anti-viral drug pleconaril that shows promise against picornavirus and BTA-798 testing. The oral form of pleconaril has a safety problem and aerosol form is being studied. DRACO, broad-spectrum antiviral therapy, has demonstrated early effectiveness in treating rhinovirus, as well as other viral infections.
The genome for all known human rhinovirus strains has been sequenced.
References
- The work quoted
- Eccles, Ronald; Weber, Olaf, eds. (2009). Common Cold . Basel: BirkhÃÆ'¤user. ISBN: 978-3764398941. Ã,
External links
Media related to common flu in Wikimedia Commons
- Common fluid in Curlie (based on DMOZ)
Source of the article : Wikipedia
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