Common cold: Difference between revisions
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{{DiseaseDisorder infobox |
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Common cold...some say its common but all i know its called thee stig |
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| Name = Common cold |
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| Image = Rhinovirus.PNG |
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| Caption = Molecular surface of one variant of human [[rhinovirus]]. |
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| ICD10 = {{ICD10|J|00|0|j|00}} |
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| ICD9 = {{ICD9|460}} |
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| DiseasesDB = 31088 |
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| MedlinePlus = 000678 |
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| eMedicineSubj = aaem |
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| eMedicineTopic = 118 |
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| eMedicine_mult = {{eMedicine2|med|2339}} |
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| MeshID = D003139 |
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}} |
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The '''common cold''' ('''acute viral rhinopharyngitis''', '''acute coryza''', '''viral upper respiratory tract infection''', or '''a cold''') is a [[wiktionary:contagious|contagious]], [[virus (biology)|viral]] [[infectious disease]] of the upper [[respiratory system]], primarily caused by [[rhinovirus]]es, ([[picornavirus]]es) or [[coronavirus]]es. It is the most common infectious disease in humans;<ref>{{cite web|url=http://www.bbc.co.uk/health/conditions/commoncold.shtml|title=The Common Cold|last=Macnair|first=Dr. Trisha|work=bbc.co.uk Health|publisher=BBC|accessdate=2009-09-30}}</ref> there is no known cure, but it is very rarely fatal. |
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Collectively, colds, influenza, and other infections with similar symptoms are included in the diagnosis of [[influenza-like illness]]. Often, influenza and the common cold are mistaken for each other, even by professional healthcare workers, but most of the recommended home treatments (drinking plenty of warm fluids, keeping warm, etc.) are similar if not the same. The symptoms of influenza often include a fever and are more severe than the cold. |
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==Symptoms== |
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Common symptoms are [[cough]], [[sore throat]], [[runny nose]], [[nasal congestion]], and [[sneeze|sneezing]]; sometimes accompanied by [[conjunctivitis|'pink eye']], [[myalgia|muscle aches]], [[fatigue (medical)|fatigue]], [[malaise]], [[headache]]s, [[muscle weakness]], uncontrollable [[shivering]], [[Anorexia (symptom)|loss of appetite]], and rarely extreme exhaustion. Fever is more commonly a symptom of [[influenza]], another viral [[upper respiratory tract infection]] (URTI) whose symptoms broadly overlap with the cold<ref name=Eccles2005>{{cite journal |author=Eccles R |title=Understanding the symptoms of the common cold and influenza |journal=Lancet Infect Dis |volume=5 |issue=11 |pages=718–25 |year=2005 |month=November |pmid=16253889 |doi=10.1016/S1473-3099(05)70270-X |url=}}</ref> but are more severe.<ref name="Nordenberg1999">{{cite web | last = Nordenberg | first = Tamar | title = Colds and Flu: Time Only Sure Cure | publisher = [[Food and Drug Administration]] |month=May | year=1999 | url = http://www.fda.gov/fdac/features/896_flu.html | accessdate = 2007-06-13}}</ref> Symptoms may be more severe in infants and young children (due to their [[immune system]] not being fully developed) as well as the elderly (due to their immune system often being weakened). |
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Those suffering from colds often report a sensation of chilliness even though the cold is not generally accompanied by fever, and although [[rigor (medicine)|chills]] are generally associated with fever, the sensation may not always be caused by actual fever.<ref name=Eccles2005/> In one study, 60% of those suffering from a sore throat and upper respiratory tract infection reported headaches<ref name=Eccles2005/>, often due to [[nasal congestion]]. The symptoms of a cold usually resolve after about one week; however, it is not rare that symptoms last up to three weeks.<ref name=Heik2003/> |
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===Complications=== |
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The common cold can lead to [[Opportunistic infection|opportunistic]] [[coinfection]]s or [[superinfection]]s such as [[acute bronchitis]], [[bronchiolitis]], [[croup]], [[pneumonia]], [[sinusitis]], [[otitis media]], or [[strep throat]]. People with chronic lung diseases such as [[asthma]] and [[COPD]] are especially vulnerable. Colds may cause acute exacerbations of [[asthma]], [[emphysema]] or [[chronic bronchitis]].<ref name="coldorg"/> |
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==Cause and susceptibility== |
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The common cold is most often caused by infection with one of the 99 known [[serovar|serotypes]] of [[rhinovirus]], a type of [[picornavirus]].<ref>{{Cite news | url = http://www.latimes.com/news/science/la-sci-cold13-2009feb13,0,6469591.story | title = Rhinovirus strains' genomes decoded; cold cure-all is unlikely: The strains are probably too different for a single treatment or vaccine to apply to all varieties, scientists say | author = Mary Engel | date = February 13, 2009 | newspaper = Los Angeles Times }}</ref><ref>{{Cite journal | doi = 10.1126/science.1165557 | title = Sequencing and Analyses of All Known Human Rhinovirus Genomes Reveals Structure and Evolution | year = 2009 | author = Palmenberg, A. C. | journal = Science | pmid = 19213880 | volume = 324 | pages = 55}}</ref> Around 30-50% of colds are caused by rhinoviruses.<ref name=Eccles2005/> Other viruses causing colds are [[coronavirus]] (causing 10-15%<ref name=Eccles2005/>), [[human parainfluenza viruses]], [[human respiratory syncytial virus]], [[Adenoviridae|adenoviruses]], [[enterovirus]]es, or [[metapneumovirus]].<ref name=NIAID2006/> 5-15% are caused by [[influenza]] viruses.<ref name=Eccles2005/> In total over 200 serologically different viral types cause colds.<ref name=Eccles2005/> Coronaviruses are particularly implicated in adult colds. Of over 30 coronaviruses, 3 or 4 cause infections in humans, but they are difficult to grow in the laboratory and their significance is thus less well-understood.<ref name="NIAID2006"/> Due to the many different types of viruses and their tendency for continuous mutation, it is impossible to gain complete immunity to the common cold. |
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===Sleep=== |
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Lack of sleep has been associated with the common cold. Those who sleep fewer than 7 hours per night were three times more likely to develop an infection when exposed to a rhinovirus when compared to those who sleep more than 8 hours per night.<ref>{{cite journal |author=Cohen S, Doyle WJ, Alper CM, Janicki-Deverts D, Turner RB |title=Sleep habits and susceptibility to the common cold |journal=Arch. Intern. Med. |volume=169 |issue=1 |pages=62–7 |year=2009 |month=January |pmid=19139325 |doi=10.1001/archinternmed.2008.505 |url=}}</ref> |
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===Vitamin D=== |
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A 2009 study found that low [[blood serum]] levels of [[vitamin D]] were associated with increased rates of the common cold.<ref>{{cite journal |author=Ginde AA, Mansbach JM, Camargo CA |title=Association between serum 25-hydroxyvitamin D level and upper respiratory tract infection in the Third National Health and Nutrition Examination Survey |journal=Arch. Intern. Med. |volume=169 |issue=4 |pages=384–90 |year=2009 |month=February |pmid=19237723 |doi=10.1001/archinternmed.2008.560 |url=}}</ref> A randomized controlled trial found that 104 post-menopausal African American women living in New York given vitamin D were three times less likely to report cold and flu symptoms than 104 placebo controls. A low dose (800 IU/day) not only reduced reported incidence, it abolished the seasonality of reported colds and flu. A higher dose (2000 IU/day), given during the last year of the trial, virtually eradicated all reports of colds or flu.<ref>{{cite journal |author=Cannell JJ, Zasloff M, Garland CF, Scragg R, Giovannucci E |title=On the epidemiology of influenza |journal=Virol. J. |volume=5 |issue= |pages=29 |year=2008 |pmid=18298852 |pmc=2279112 |doi=10.1186/1743-422X-5-29 |url=http://www.virologyj.com/content/5/1/29#IDASINYH}}</ref> |
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===Exposure to cold weather=== |
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An ancient belief still common today claims that a cold can be "caught" by prolonged exposure to cold weather such as rain or winter conditions, which is where the disease got its name.<ref>Zuger, Abigail [http://query.nytimes.com/gst/fullpage.html?res=9D02E1DD163FF937A35750C0A9659C8B63 'You'll Catch Your Death!' An Old Wives' Tale? Well . . .] ''[[The New York Times]]'' (March 4, 2003). Retrieved on 12-17-08.</ref> Although common colds are seasonal, with more occurring during winter, experiments so far have failed to produce evidence that short-term exposure to cold weather or direct chilling increases susceptibility to infection, implying that the seasonal variation is instead due to a change in behaviors such as increased time spent indoors at close proximity to others.<ref name="NIAID2006"/><ref name="pmid13559211">{{cite journal | author = Dowling HF, Jackson GG, Spiesman IG, Inouye T | title = Transmission of the common cold to volunteers under controlled conditions. III. The effect of chilling of the subjects upon susceptibility | journal = American journal of hygiene | volume = 68 | issue = 1 | pages = 59–65 | year = 1958 | pmid = 13559211}}</ref><ref name="pmid12357708">{{cite journal | author = Eccles R | title = Acute cooling of the body surface and the common cold | journal = Rhinology | volume = 40 | issue = 3 | pages = 109–14 | year = 2002 | pmid = 12357708}}</ref><ref>{{cite journal | author = Douglas, R.G.Jr, K.M. Lindgren, and R.B. Couch | title = Exposure to cold environment and rhinovirus common cold. Failure to demonstrate effect | journal = New Engl. J. Med | volume = 279 | year = 1968}}<!-- Please confirm, was the follow ref the correct one?--></ref><ref>{{cite journal |author=Douglas RC, Couch RB, Lindgren KM |title=Cold doesn't affect the "common cold" in study of rhinovirus infections |journal=JAMA |volume=199 |issue=7 |pages=29–30 |year=1967 |pmid=4289651 |doi= 10.1001/jama.199.7.29|url=}}</ref> |
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With respect to the causation of cold-like ''symptoms'', researchers at the Common Cold Centre at [[Cardiff University]]<ref name="CCCentre"/> conducted a study to "test the hypothesis that acute cooling of the feet causes the onset of common cold symptoms."<ref name="pmid16286463">{{cite journal | author = Johnson C, Eccles R | title = Acute cooling of the feet and the onset of common cold symptoms | journal = Family Practice | volume = 22 | issue = 6 | pages = 608–13 | year = 2005 | pmid = 16286463 | doi = 10.1093/fampra/cmi072 | url = http://fampra.oxfordjournals.org/cgi/content/full/22/6/608}}</ref><ref>[http://news.bbc.co.uk/2/hi/uk_news/wales/4433496.stm ''Mothers 'were right' over colds''], [[BBC News]], 14 November 2005</ref><ref>[http://www.medpagetoday.com/Pulmonary/URIstheFlu/tb/2136 ''Cold Feet? Aah-Choo!''], Michael Smith, Medical News: Flu & URI, Medpagetoday, November 14, 2005</ref> The study measured the subjects' self-reported cold symptoms, and belief they had a cold, but not whether an actual respiratory infection developed. It found that a significantly greater number of those subjects chilled developed cold symptoms 4 or 5 days after the chilling. It concludes that the onset of common cold ''symptoms'' can be caused by acute chilling of the feet. Some possible explanations were suggested for the symptoms, such as placebo, or constriction of blood vessels of the nasal passages which might lead to reduced immunity, however "further studies are needed to determine the relationship of symptom generation to any respiratory infection." |
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Another possibility which remains to be explored involves the role that proteins of the [[complement system]] play in the prevention of a sustained infection. Decreased temperature may result in a drop in tissue permeability and, as a result, may lead to reduced plasma leakage. Among the many proteins suspended in plasma are complement proteins (e.g. C3) which serve to disable, destroy, or tag for destruction foreign particulate (in this case viral [[capsid]]s). Thus, sustained exposure to cold may inhibit the effectiveness of the complement system and allow the virus a better chance of establishing a state of infection.{{Citation needed|date=September 2009}} |
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[[ICAM-1]], the receptor that Rhinovirus binds to in order to infect cells, is known to increase in number and receptiveness in response to many irritants, including dust and pollen. That a cold climate in combination with varying degrees of humidity can act as a similar "irritant" needs to be investigated.{{Citation needed|date=September 2009}} |
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==Pathophysiology== |
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[[Image:Illu conducting passages.jpg|thumb|The common cold is a disease of the [[upper respiratory tract]]]] |
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The common cold virus is transmitted mainly from contact with the saliva or nasal secretions of an infected person, either directly, in [[aerosol]] form generated by coughing and sneezing, or from contaminated surfaces.<ref>{{Cite web | url = http://www.nytimes.com/2007/12/05/health/research/05flu.html | title = Study Shows Why the Flu Likes Winter | author = Gina Kolata | date = December 5, 2007 | publisher = New York Times}}</ref> |
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Symptoms are not necessary for viral shedding or transmission, as a percentage of asymptomatic subjects exhibit viruses in nasal swabs.<ref name=gsacc>{{cite web | url=http://dh.sa.gov.au/pehs/Youve-got-what/ygw-common-cold.pdf | title=Common Cold | publisher=Department of Health, Government of South Australia | year=2005 | accessdate=2007-06-20|format=PDF}}</ref> It is generally not possible to identify the virus type through symptoms, although influenza can be distinguished by its sudden onset, fever, and cough.<ref name=Eccles2005/> |
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The major entry point for the virus is normally the nose, but can also be the eyes (in this case drainage into the [[nasopharynx]] would occur through the [[nasolacrimal duct]]). From there, it is transported to the back of the nose and the [[adenoid]] area. The virus then attaches to a receptor, [[ICAM-1]], which is located on the surface of [[cell (biology)|cells]] of the lining of the nasopharynx. The receptor fits into a docking port on the surface of the virus. Large amounts of virus receptor are present on cells of the adenoid. After attachment to the receptor, virus is taken into the cell, where it starts an infection.<ref name="coldorg">{{cite web | author = Gwaltney, JM, Hayden, FG | title = Understanding the Common Cold: How Cold Virus Infection Occurs |year=2007| url = http://www.commoncold.org/undrstn3.htm }}</ref> Rhinovirus colds do not generally cause damage to the nasal [[epithelium]]. [[Macrophage]]s trigger the production of [[cytokines]], which in combination with mediators cause the symptoms. Cytokines cause the systemic effects. The mediator [[bradykinin]] plays a major role in causing the local symptoms such as sore throat and nasal irritation.<ref name=Eccles2005/> |
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The common cold is self-limiting, and the host's [[immune system]] effectively deals with the infection. Within a few days, the body's [[humoral]] immune response begins producing specific [[antibodies]] that can prevent the virus from infecting cells. Additionally, as part of the cell-mediated immune response, [[leukocytes]] destroy the virus through [[phagocytosis]] and destroy infected cells to prevent further viral replication. In healthy, immunocompetent individuals, the common cold resolves in seven days on average.<ref name="coldorg"/> |
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===Incubation period and progression of disease=== |
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The upper respiratory viral replication cycle begins 8 to 12 hours after initial infection.<ref name="coldorg">{{cite web | author = Gwaltney, JM, Hayden, FG | title = Understanding Colds |year=2006 | url = http://www.commoncold.org/index.htm | accessdate = 2007-07-03}}</ref> Symptoms usually begin 2 to 5 days after initial infection but occasionally occur in as little as 10 hours after.<ref>{{cite web | author = Patsy Hamilton | url =http://www.healthguidance.org/entry/6125/1/Facts-about-the-Common-Cold-Incubation-Period.html |title=Facts about the Common Cold Incubation Period | accessdate = 2007-07-03}}</ref> Symptoms peak 2–3 days after symptom onset, whereas influenza symptom onset is constant and immediate.<ref name=Eccles2005/> The symptoms usually resolve spontaneously in 7 to 10 days but some can last for up to three weeks.<ref name=Heik2003/> |
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The first indication of an upper respiratory virus is often a [[Pharyngitis|sore or scratchy throat]]. Other common symptoms are [[rhinorrhea|runny nose]], [[Nasal congestion|congestion]], and [[sneeze|sneezing]].<ref name="NIAID2006">{{cite web | title = Common Cold | publisher = [[National Institute of Allergy and Infectious Diseases]] | date = [[2006-11-27]] | url = http://www3.niaid.nih.gov/healthscience/healthtopics/colds/ | accessdate = 2007-06-11}}</ref> These are sometimes accompanied by [[myalgia|muscle aches]], [[Fatigue (medical)|fatigue]], [[malaise]], [[headache]], [[Muscle weakness|weakness]], or [[anorexia (symptom)|loss of appetite]].<ref name="CCCentre">{{cite web | url =http://www.cardiff.ac.uk/biosi/subsites/cold/commoncold.html | title = Common Cold Centre | accessdate = 2007-09-06 |year=2006 | publisher = Cardiff University }}</ref> Cough and fever generally indicate [[influenza]] rather than an upper respiratory virus with a positive predictive value of around 80%.<ref name=Eccles2005/> |
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Symptoms may be more severe in infants and young children, and in these cases it may include fever and [[urticaria|hives]].<ref name=CPS2>{{cite web | title = Colds in children | publisher = Canadian Pediatric Society |month=October | year=2005 | url = http://www.cps.ca/caringforkids/whensick/colds.htm| accessdate = 2007-07-16 }}</ref> Upper respiratory viruses may also be more severe in smokers.<ref name="ALA2005">{{cite web | title = A Survival Guide for Preventing and Treating Influenza and the Common Cold | publisher = [[American Lung Association]] |month=August | year=2005 | url =http://www.lungusa.org/site/pp.asp?c=dvLUK9O0E&b=35873#done | accessdate = 2007-06-11}}</ref> |
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==Prevention== |
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The best way to avoid a cold is to wash hands thoroughly and regularly; and to avoid touching the eyes, nose, mouth, and face. Anti-bacterial soaps have no extraordinary effect on the cold virus; it is the mechanical action of hand washing with the soap that removes the virus particles.<ref>{{cite web|url=http://www.phac-aspc.gc.ca/chn-rcs/handwash-eng.php |title=Staying healthy is in your hands - Public Health Agency Canada |format= |work= |accessdate=2008-05-05|date=2008-04-17}}</ref> Rhinoviruses can live up to 3 hours outside the body on the skin or objects.<ref name="NIAID2006"/> |
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In 2002, the [[Centers for Disease Control and Prevention]] recommended alcohol-based hand gels as an effective method for reducing infectious viruses on the hands of health care workers.<ref>{{cite journal |
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| last = Boyce |
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| first = John M. |
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| coauthors = Didier Pittet |
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| title = Guideline for Hand Hygiene in Health-Care Settings: Guideline for Hand Hygiene in Health-Care Settings Recommendations of the Healthcare Infection Control Practices Advisory Committee and the HICPAC/SHEA/APIC/IDSA Hand Hygiene Task Force |
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| journal = [[Morbidity and Mortality Weekly Report]] |
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| date = [[2002-10-25]] |
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| volume = 51 |
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| issue = RR-16 |
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| url = http://www.cdc.gov/mmwr/PDF/rr/rr5116.pdf |
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| format = pdf |
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| pmid = 12418624 |
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| accessdate = 2007-06-21 |
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}}</ref> |
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Alcohol-based hand sanitizer however does not completely eliminate the cold-causing rhinovirus.<ref>{{cite journal |last1=Turner |first1=Ronald |last2=Hendley |first2=J. Owen |year=2005 |title=Virucidal hand treatments for prevention of rhinovirus infection |journal=Journal of Antimicrobial Chemotherapy |volume=56 |issue=5 |pages=805-807 |url=http://jac.oxfordjournals.org/cgi/content/full/56/5/805 |doi=10.1093/jac/dki329 }}</ref> |
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Neither soap and water nor alcohol gels provide residual protection from re-infection. |
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The common cold is caused by a large variety of viruses, which mutate quite frequently during reproduction, resulting in constantly changing virus strains. Thus, successful [[immunization]] is highly improbable. |
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[[Probiotics]] in children 3 – 5 years old were found effective in decreases cold symptoms when taken over 6 months.<ref>{{cite journal |author=Leyer GJ, Li S, Mubasher ME, Reifer C, Ouwehand AC |title=Probiotic effects on cold and influenza-like symptom incidence and duration in children |journal=Pediatrics |volume=124 |issue=2 |pages=e172–9 |year=2009 |month=August |pmid=19651563 |doi=10.1542/peds.2008-2666 |url=}}</ref> |
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==Treatment== |
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[[Image:Pneumonia strikes like a man eating shark.jpg|thumb|Poster encouraging citizens to "Consult your Physician" for treatment of the common cold]] |
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The common cold usually resolves spontaneously in 7 to 10 days, but some symptoms can last for up to three weeks.<ref name=Heik2003>{{cite journal |author=Heikkinen T, Järvinen A |title=The common cold |journal=Lancet |volume=361 |issue=9351 |pages=51–9 |year=2003 |month=January |pmid=12517470 |doi=10.1016/S0140-6736(03)12162-9 |url=}}</ref> There are no medications or herbal remedies proven to shorten the duration of illness. Treatment is symptomatic support usually via providing [[analgesics]] for fever, headache and myalgia, nasal decongestants and antihistamines for nasal congestion and runniness, and lozenges for sore throat. |
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===Conservative management=== |
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The [[National Institute of Allergy and Infectious Diseases]] suggests getting plenty of rest, drinking fluids to maintain hydration, [[gargling]] with warm salt water, using cough drops, throat sprays, or [[over-the-counter drug|over-the-counter]] pain or cold medicines.<ref name="NIAID2006"/> Saline nasal drops may help alleviate congestion.<ref name=PDRCC>{{cite web| title = Common Cold| work = PDRHealth| publisher = Thomson Healthcare| url = http://www.pdrhealth.com/disease/disease-mono.aspx?contentFileName=BHG01ID25.xml&contentName=Common+Cold&contentId=30| accessdate = 2007-07-11}}</ref> |
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Treatments that help alleviate symptoms include [[analgesics]] ( such as [[NSAIDs]]<ref>{{cite journal |author=Kim SY, Chang YJ, Cho HM, Hwang YW, Moon YS |title=Non-steroidal anti-inflammatory drugs for the common cold |journal=Cochrane Database Syst Rev |volume= |issue=3 |pages=CD006362 |year=2009 |pmid=19588387 |doi=10.1002/14651858.CD006362.pub2 |url=}}</ref> ), [[decongestants]], and [[cough suppressant]]s,{{Citation needed|date=February 2009}} first-generation [[antihistamine]]s such as [[brompheniramine]], [[chlorpheniramine]], [[diphenhydramine]] and [[clemastine]] (which reduce mucus gland secretion and thus combat blocked/runny noses but also may make the user drowsy). Second-generation antihistamines do not have a useful effect on colds.{{Citation needed|date=July 2009}} |
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[[Vitamin C]] in normal or mega doses has not been shown to be beneficial in a normal population for the prevention or treatment of the common cold. It however might be beneficial in people exposed to periods of severe physical exercise or cold environments.<ref>{{cite journal | journal=Cochrane Database Syst Rev | volume= | issue=3 | pages=CD000980 | date=2007 | author=Douglas RM, Hemil? H, Chalker E, Treacy B. | title=Vitamin C for preventing and treating the common cold. | pmid=17636648 | doi = 10.1002/14651858.CD000980.pub3 }}</ref> |
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Various [[Cough medicine|cold medicines]] exist however little evidence suggest they are any more effective than simple [[analgesics]]. They include [[antitussives]], [[antihistamines]] and [[decongestants]] usually in combination with an analgesic. They are not recommended for use in children because evidence does not support their effectiveness and there are concerns of harm.<ref>{{cite web |url=http://www.uptodate.com/online/content/topic.do?topicKey=pedi_id/16291&selectedTitle=1~116&source=search_result#20 |title=UpToDate Inc. |format= |work= |accessdate=}}</ref> |
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===Antibiotics=== |
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[[Antibiotics]] only target [[bacteria]] and thus do not have any beneficial effect against the common cold. |
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===Antivirals=== |
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There are no approved [[antiviral drug]]s for the common cold. |
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===Alternative treatments=== |
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{{Main|Alternative treatments used for the common cold}} |
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Many alternative treatments are used to treat the common cold. None, however, are supported by solid scientific evidence.<ref name="ALA2005">{{cite web | title = A Survival Guide for Preventing and Treating Influenza and the Common Cold | publisher = [[American Lung Association]] |month=August | year=2005 | url = http://www.lungusa.org/site/pp.asp?c=dvLUK9O0E&b=35873#done | accessdate = 2007-06-11}}</ref> Some alternative treatments, like [[echinacea]], have not been shown to have any effects on the frequency of infection, the duration of infection, or the severity of symptoms of the common cold.<ref>{{cite web | title = An Evaluation of Echinacea angustifolia in Experimental Rhinovirus Infections | publisher = [[New England Journal of Medicine]] |month=July | year=2005 | url = http://content.nejm.org/cgi/content/abstract/353/4/341}}</ref><ref>{{cite web | title = Echinacea for the Prevention and Treatment of Colds in Adults: Research Results and Implications for Future Studies | publisher = [[National Center for Complementary and Alternative Medicine]] |month=October | year=2005 | url = http://nccam.nih.gov/research/results/echinacea_rr.htm}}</ref> Other alternative treatments which similarly lack solid scientific evidence include [[calendula]]<ref>Jimenez-Medina E, Garcia-Lora A, Paco L et al. (2006). A new extract of the plant Calendula officinalis produces a dual in vitro effect: cytotoxic anti-tumor activity and lymphocyte activation. BMC Cancer. 6:6.</ref>, [[ginger]]<ref>Jakes, Susan (2007-01-15). "Beverage of Champions". Retrieved on 2007-08-02.</ref>, [[garlic]]<ref>Hamel, Paul B. and Mary U. Chiltoskey 1975 Cherokee Plants and Their Uses -- A 400 Year History. Sylva, N.C. Herald Publishing Co. (p. 35)</ref> and [[vitamin C]] supplements.<ref>ROBERT F. CATHCART III (1996). "Preparation of Sodium Ascorbate for IV and IM Use". orthomed.com. Retrieved on 2007-02-21</ref> |
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==Prognosis== |
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Although the disease is generally mild and self-limiting, patients with common colds often seek professional medical help, use [[over-the-counter drug]]s, and may miss school or work days. The annual cumulative societal cost of the common cold in developed countries is considerable in terms of money spent on remedies, and hours of lost productivity. |
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There are no [[antiviral drug]]s approved to treat or cure the infection; all medications used are [[palliative care|palliative]] and treat symptoms only. Alternative treatments such as [[vitamin C]], [[echinacea]], and [[zinc]] have been proposed but none of them has been shown to decrease the duration of the illness,<ref name="ALA2005" /> and thus none of them is approved by the [[Food and Drug Administration]] or [[European Medicines Agency]]. To prevent infection, washing or disinfecting<ref name="MEDNET">{{cite web|url=http://www.medicinenet.com/script/main/art.asp?articlekey=53472|title=10 Tips to Prevent the Common Cold|last=Stoppler|first=Melissa|date=2008-10-07|publisher=MedicineNet|accessdate=2009-05-16}}</ref> hands has been found effective, as this minimizes person-to-person transmission of the virus. |
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==Epidemiology== |
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Upper respiratory tract infections are the most common infectious diseases among adults, who have two to four respiratory infections annually.<ref name="pmid4014285">{{cite journal | author = Garibaldi RA | title = Epidemiology of community-acquired respiratory tract infections in adults. Incidence, etiology, and impact | journal = Am. J. Med. | volume = 78 | issue = 6B | pages = 32–7 | year = 1985 | pmid = 4014285 | doi = 10.1016/0002-9343(85)90361-4}}</ref> Children may have six to ten colds a year (and up to 12 colds a year for school children).<ref name="NIAID2006"/><ref name="pmid17323712">{{cite journal | author = Simasek M, Blandino DA | title = Treatment of the common cold | journal = American family physician | volume = 75 | issue = 4 | pages = 515–20 | year = 2007 | pmid = 17323712 | url = http://www.aafp.org/afp/20070215/515.html}}</ref> In the United States, the incidence of colds is higher in the fall (autumn) and winter, with most infections occurring between September and April. The seasonality may be due to the start of the school year, or due to people spending more time indoors (thus in closer proximity with each other) increasing the chance of transmission of the virus.<ref name="NIAID2006"/> |
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==History== |
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[[Image:Definition of a Cold by Benjamin Franklin Page 1.jpg|thumb|"Definition of a Cold." [[Benjamin Franklin]]'s notes for a paper he intended to write on the common cold.]] |
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The name "common cold" came into use in the 16th century, due to the similarity between its symptoms and those of exposure to cold weather.<ref>{{cite web | publisher=Online Etymology Dictionary | url=http://www.etymonline.com/index.php?term=cold | title=Cold | accessdate=2008-01-12 }}</ref> Norman Moore relates in his history of the Study of Medicine that [[James I of England|James I]] continually suffered from nasal colds, which were then thought to be caused by [[Polyp (medicine)|polypi]], [[sinus (anatomy)|sinus]] trouble, or [http://cancerweb.ncl.ac.uk/cgi-bin/omd?autotoxaemia autotoxaemia].<ref>{{cite journal | author = Wylie, A, | title = Rhinology and laryngology in literature and Folk-Lore | journal = The Journal of Laryngology & Otology | volume = 42 | issue = 2 | pages = 81–87 | year = 1927 | doi = 10.1017/S0022215100029959}}</ref> |
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In the 18th century, [[Benjamin Franklin]] considered the causes and prevention of the common cold. After several years of research he concluded: "People often catch cold from one another when shut up together in small close rooms, coaches, etc. and when sitting near and conversing so as to breathe in each other's transpiration." Although viruses had not yet been discovered, Franklin hypothesized that the common cold was passed between people through the air. He recommended exercise, bathing, and moderation in food and drink consumption to avoid the common cold.<ref>{{cite web | url = http://www.loc.gov/exhibits/treasures/franklin-scientist.html | title = Scientist and Inventor: Benjamin Franklin: In His Own Words... (AmericanTreasures of the Library of Congress) | accessdate = 2007-12-23}}</ref> Franklin's theory on the transmission of the cold was confirmed some 150 years later.<ref name="pmid14795755">{{cite journal | author = Andrewes CH, Lovelock JE, Sommerville T | title = An experiment on the transmission of colds | journal = Lancet | volume = 1 | issue = 1 | pages = 25–7 | year = 1951 | pmid = 14795755 | doi =10.1016/S0140-6736(51)93497-6 }}</ref> |
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===Common Cold Unit=== |
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{{Main|Common Cold Unit}} |
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In the [[United Kingdom]], the [[Common Cold Unit]] was set up by the [[Medical Research Council (UK)|Medical Research Council]] in 1946. The unit worked with volunteers who were infected with various viruses.<ref>{{cite book | title = Das Buch der verrückten Experimente (Broschiert) | author = Reto U. Schneider | year = 2004 | isbn = 344215393X | url = http://www.verrueckte-experimente.de/index_e.html | publisher = Goldmann | location = München}}</ref> The [[rhinovirus]] was discovered there.<ref name="pmid2849371">{{cite journal |
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|author=Tyrrell DA |
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|title=Hot news on the common cold |
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|journal=Annu. Rev. Microbiol. |
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|volume=42 |
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|issue= |
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|pages=35–47 |
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|year=1988 |
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|pmid=2849371 |
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|doi=10.1146/annurev.mi.42.100188.000343 |
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}}</ref> In the late 1950s, researchers were able to grow one of these cold viruses in a [[tissue culture]], as it would not grow in fertilized chicken eggs, the method used for many other viruses. In the 1970s, the CCU demonstrated that treatment with [[interferon]] during the incubation phase of rhinovirus infection protects somewhat against the disease<ref name="pmid2438740">{{cite journal |
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|author=Tyrrell DA |
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|title=Interferons and their clinical value |
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|journal=Rev. Infect. Dis. |
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|volume=9 |
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|issue=2 |
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|pages=243–9 |
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|year=1987 |
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|pmid=2438740 |
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|doi= |
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}}</ref>, but no practical treatment could be developed. The unit was closed in 1989, two years after it completed research of zinc gluconate lozenges in the prophylaxis and treatment of rhinovirus colds, the only successful treatment in the history of the unit.<ref>{{cite journal |
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| journal = J Antimicrob Chemother. |
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| year = 1987 |
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| month = December |
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| volume = 20 |
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| issue = 6 |
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| pages = 893–901 |
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| title = Prophylaxis and treatment of rhinovirus colds with zinc gluconate lozenges |
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| last = Al-Nakib |
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| first = W |
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| coauthors = Higgins PG, Barrow I, Batstone G, Tyrrell DA. |
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| pmid = 3440773 |
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| doi = 10.1093/jac/20.6.893 |
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}}</ref> |
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==Social and cultural== |
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===Economic cost=== |
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[[Image:The Cost Of The Common Cold & Influenza.jpg|thumb|A [[UK|British]] poster from [[World War II]] describing the cost of the common cold<ref>http://vads.bath.ac.uk/flarge.php?uid=33443&sos=0</ref>]] |
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{{Globalize/USA}} |
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In the United States, the common cold leads to 75 to 100 million physician visits annually at a conservative cost estimate of $7.7 billion per year. Americans spend $2.9 billion on over-the-counter drugs and another $400 million on prescription medicines for symptomatic relief.<ref name="pmid4014285"/><ref name="pmid12588210">{{cite journal | author = Fendrick AM, Monto AS, Nightengale B, Sarnes M | title = The economic burden of non-influenza-related viral respiratory tract infection in the United States | journal = Arch. Intern. Med. | volume = 163 | issue = 4 | pages = 487–94 | year = 2003 | pmid = 12588210 | url = http://archinte.ama-assn.org/cgi/content/full/163/4/487 | doi = 10.1001/archinte.163.4.487}}</ref> |
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More than one-third of patients who saw a doctor received an antibiotic prescription, which has implications for antibiotic resistance from overuse of such drugs.<ref name="pmid12588210"/> |
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An estimated 22 to 189 million school days are missed annually due to a cold. As a result, parents missed 126 million workdays to stay home to care for their children. When added to the 150 million workdays missed by employees suffering from a cold, the total economic impact of cold-related work loss exceeds $20 billion per year.<ref name="NIAID2006"/><ref name="pmid4014285"/><ref name="pmid12588210"/> |
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==Research== |
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[[Biota Holdings]] are developing a drug, currently know as BTA798, which targets rhinovirus. The drug has recently successfully completed Phase IIa clinical trials.<ref name="mailonline">{{cite web| url = http://www.dailymail.co.uk/health/article-1043719/The-new-pill-signal-death-common-cold.html | title = The new pill that could signal the death of the common cold| month = August| year = 2008| accessdate = 2009-08-19}}</ref><ref name="biotarelease">{{cite web| url = http://www.biota.com.au/uploaded/154/1021521_38hrvphaseiiastudyachieve.pdf | title = Biota Press Release | month = June| year = 2009| accessdate = 2009-08-19}}</ref> |
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[[ViroPharma]] and [[Schering-Plough]] are developing an antiviral drug, [[pleconaril]], that targets [[Picornaviridae|picornaviruses]], the viruses that cause the majority of common colds. [[Pleconaril]] has been shown to be effective in an [[Route of administration|oral]] form.<ref>{{cite journal| last = Pevear| first = Daniel C.| coauthors = Tina M. Tull, Martin E. Seipel, James M. Groarke| year = 1999| month = September| title = Activity of Pleconaril against Enteroviruses| journal = Antimicrobial Agents and Chemotherapy| volume = 43| issue = 9| pages = 2109–2115| url =http://aac.asm.org/cgi/content/full/43/9/2109| language =| pmid = 10471549| date = 1999-09-01| day = 01}}</ref><ref>{{cite journal| quotes =| last = McConnell| first = J.| date = [[2 October]] [[1999]] | title = Enteroviruses succumb to new drug| journal = The Lancet | volume = 354 | issue = 9185 | pages = 1185 | doi = 10.1016/S0140-6736(05)75393-9}}</ref> |
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[[Schering-Plough]] is developing an [[Route of administration|intra-nasal]] formulation that may have fewer adverse effects.<ref name="CTgov">{{cite web| url = http://www.clinicaltrials.gov/ct/gui/show/NCT00394914| title = Effects of Pleconaril Nasal Spray on Common Cold Symptoms and Asthma Exacerbations Following Rhinovirus Exposure (Study P04295AM2)| month = March| year = 2007| accessdate = 2007-04-10| publisher = U.S. [[National Institutes of Health]]| work = ClinicalTrials.gov}}</ref> |
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Researchers from [[University of Maryland, College Park]] and [[University of Wisconsin–Madison]] have mapped the [[genome]] for all known virus strains that cause the common cold.<ref name="CTgov">{{cite web| url = http://www.cnn.com/2009/HEALTH/02/12/cold.genome/| title = Genetic map of cold virus a step toward cure, scientists say| month = March| year = 2009| accessdate = 2009-04-28| publisher = [[CNN]]| work = Val Willingham}}</ref> |
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==See also== |
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*[[Influenza]] |
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*[[Rhinitis]] |
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*[[Acute pharyngitis]] |
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*[[Severe acute respiratory syndrome]] |
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==References== |
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{{refs|3}} |
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==External links== |
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{{sisterlinks|display=Common cold}} |
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*[http://www.nhsdirect.nhs.uk/Sat/Topics/ColdsAndFlu.aspx?Host=Nhsd&SyndicationPartnerGuid=d19370ea-a100-407d-9695-b73407f701c7&TopicGuid=8c903315-a302-412a-bfae-9cb576d4b4cd Cold and flu advice] (NHS Direct) |
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{{Viral diseases}} |
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{{Respiratory pathology}} |
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{{Common Cold}} |
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{{DEFAULTSORT:Common Cold}} |
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[[Category:Viruses]] |
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[[Category:Viral diseases]] |
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[[Category:Inflammations|Nasopharyngitis]] |
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[[Category:Respiratory diseases]] |
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[[Category:Infectious diseases]] |
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[[ar:زكام]] |
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[[an:Resfriato común]] |
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[[ca:Refredat]] |
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[[ceb:Sip-on]] |
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[[cs:Nachlazení]] |
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Revision as of 13:21, 10 November 2009
Common cold | |
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Specialty | Family medicine, infectious diseases, otorhinolaryngology ![]() |
The common cold (acute viral rhinopharyngitis, acute coryza, viral upper respiratory tract infection, or a cold) is a contagious, viral infectious disease of the upper respiratory system, primarily caused by rhinoviruses, (picornaviruses) or coronaviruses. It is the most common infectious disease in humans;[1] there is no known cure, but it is very rarely fatal.
Collectively, colds, influenza, and other infections with similar symptoms are included in the diagnosis of influenza-like illness. Often, influenza and the common cold are mistaken for each other, even by professional healthcare workers, but most of the recommended home treatments (drinking plenty of warm fluids, keeping warm, etc.) are similar if not the same. The symptoms of influenza often include a fever and are more severe than the cold.
Symptoms
Common symptoms are cough, sore throat, runny nose, nasal congestion, and sneezing; sometimes accompanied by 'pink eye', muscle aches, fatigue, malaise, headaches, muscle weakness, uncontrollable shivering, loss of appetite, and rarely extreme exhaustion. Fever is more commonly a symptom of influenza, another viral upper respiratory tract infection (URTI) whose symptoms broadly overlap with the cold[2] but are more severe.[3] Symptoms may be more severe in infants and young children (due to their immune system not being fully developed) as well as the elderly (due to their immune system often being weakened).
Those suffering from colds often report a sensation of chilliness even though the cold is not generally accompanied by fever, and although chills are generally associated with fever, the sensation may not always be caused by actual fever.[2] In one study, 60% of those suffering from a sore throat and upper respiratory tract infection reported headaches[2], often due to nasal congestion. The symptoms of a cold usually resolve after about one week; however, it is not rare that symptoms last up to three weeks.[4]
Complications
The common cold can lead to opportunistic coinfections or superinfections such as acute bronchitis, bronchiolitis, croup, pneumonia, sinusitis, otitis media, or strep throat. People with chronic lung diseases such as asthma and COPD are especially vulnerable. Colds may cause acute exacerbations of asthma, emphysema or chronic bronchitis.[5]
Cause and susceptibility
The common cold is most often caused by infection with one of the 99 known serotypes of rhinovirus, a type of picornavirus.[6][7] Around 30-50% of colds are caused by rhinoviruses.[2] Other viruses causing colds are coronavirus (causing 10-15%[2]), human parainfluenza viruses, human respiratory syncytial virus, adenoviruses, enteroviruses, or metapneumovirus.[8] 5-15% are caused by influenza viruses.[2] In total over 200 serologically different viral types cause colds.[2] Coronaviruses are particularly implicated in adult colds. Of over 30 coronaviruses, 3 or 4 cause infections in humans, but they are difficult to grow in the laboratory and their significance is thus less well-understood.[8] Due to the many different types of viruses and their tendency for continuous mutation, it is impossible to gain complete immunity to the common cold.
Sleep
Lack of sleep has been associated with the common cold. Those who sleep fewer than 7 hours per night were three times more likely to develop an infection when exposed to a rhinovirus when compared to those who sleep more than 8 hours per night.[9]
Vitamin D
A 2009 study found that low blood serum levels of vitamin D were associated with increased rates of the common cold.[10] A randomized controlled trial found that 104 post-menopausal African American women living in New York given vitamin D were three times less likely to report cold and flu symptoms than 104 placebo controls. A low dose (800 IU/day) not only reduced reported incidence, it abolished the seasonality of reported colds and flu. A higher dose (2000 IU/day), given during the last year of the trial, virtually eradicated all reports of colds or flu.[11]
Exposure to cold weather
An ancient belief still common today claims that a cold can be "caught" by prolonged exposure to cold weather such as rain or winter conditions, which is where the disease got its name.[12] Although common colds are seasonal, with more occurring during winter, experiments so far have failed to produce evidence that short-term exposure to cold weather or direct chilling increases susceptibility to infection, implying that the seasonal variation is instead due to a change in behaviors such as increased time spent indoors at close proximity to others.[8][13][14][15][16]
With respect to the causation of cold-like symptoms, researchers at the Common Cold Centre at Cardiff University[17] conducted a study to "test the hypothesis that acute cooling of the feet causes the onset of common cold symptoms."[18][19][20] The study measured the subjects' self-reported cold symptoms, and belief they had a cold, but not whether an actual respiratory infection developed. It found that a significantly greater number of those subjects chilled developed cold symptoms 4 or 5 days after the chilling. It concludes that the onset of common cold symptoms can be caused by acute chilling of the feet. Some possible explanations were suggested for the symptoms, such as placebo, or constriction of blood vessels of the nasal passages which might lead to reduced immunity, however "further studies are needed to determine the relationship of symptom generation to any respiratory infection."
Another possibility which remains to be explored involves the role that proteins of the complement system play in the prevention of a sustained infection. Decreased temperature may result in a drop in tissue permeability and, as a result, may lead to reduced plasma leakage. Among the many proteins suspended in plasma are complement proteins (e.g. C3) which serve to disable, destroy, or tag for destruction foreign particulate (in this case viral capsids). Thus, sustained exposure to cold may inhibit the effectiveness of the complement system and allow the virus a better chance of establishing a state of infection.[citation needed]
ICAM-1, the receptor that Rhinovirus binds to in order to infect cells, is known to increase in number and receptiveness in response to many irritants, including dust and pollen. That a cold climate in combination with varying degrees of humidity can act as a similar "irritant" needs to be investigated.[citation needed]
Pathophysiology
![](http://upload.wikimedia.org/wikipedia/commons/thumb/c/c3/Illu_conducting_passages.jpg/220px-Illu_conducting_passages.jpg)
The common cold virus is transmitted mainly from contact with the saliva or nasal secretions of an infected person, either directly, in aerosol form generated by coughing and sneezing, or from contaminated surfaces.[21]
Symptoms are not necessary for viral shedding or transmission, as a percentage of asymptomatic subjects exhibit viruses in nasal swabs.[22] It is generally not possible to identify the virus type through symptoms, although influenza can be distinguished by its sudden onset, fever, and cough.[2]
The major entry point for the virus is normally the nose, but can also be the eyes (in this case drainage into the nasopharynx would occur through the nasolacrimal duct). From there, it is transported to the back of the nose and the adenoid area. The virus then attaches to a receptor, ICAM-1, which is located on the surface of cells of the lining of the nasopharynx. The receptor fits into a docking port on the surface of the virus. Large amounts of virus receptor are present on cells of the adenoid. After attachment to the receptor, virus is taken into the cell, where it starts an infection.[5] Rhinovirus colds do not generally cause damage to the nasal epithelium. Macrophages trigger the production of cytokines, which in combination with mediators cause the symptoms. Cytokines cause the systemic effects. The mediator bradykinin plays a major role in causing the local symptoms such as sore throat and nasal irritation.[2]
The common cold is self-limiting, and the host's immune system effectively deals with the infection. Within a few days, the body's humoral immune response begins producing specific antibodies that can prevent the virus from infecting cells. Additionally, as part of the cell-mediated immune response, leukocytes destroy the virus through phagocytosis and destroy infected cells to prevent further viral replication. In healthy, immunocompetent individuals, the common cold resolves in seven days on average.[5]
Incubation period and progression of disease
The upper respiratory viral replication cycle begins 8 to 12 hours after initial infection.[5] Symptoms usually begin 2 to 5 days after initial infection but occasionally occur in as little as 10 hours after.[23] Symptoms peak 2–3 days after symptom onset, whereas influenza symptom onset is constant and immediate.[2] The symptoms usually resolve spontaneously in 7 to 10 days but some can last for up to three weeks.[4]
The first indication of an upper respiratory virus is often a sore or scratchy throat. Other common symptoms are runny nose, congestion, and sneezing.[8] These are sometimes accompanied by muscle aches, fatigue, malaise, headache, weakness, or loss of appetite.[17] Cough and fever generally indicate influenza rather than an upper respiratory virus with a positive predictive value of around 80%.[2] Symptoms may be more severe in infants and young children, and in these cases it may include fever and hives.[24] Upper respiratory viruses may also be more severe in smokers.[25]
Prevention
The best way to avoid a cold is to wash hands thoroughly and regularly; and to avoid touching the eyes, nose, mouth, and face. Anti-bacterial soaps have no extraordinary effect on the cold virus; it is the mechanical action of hand washing with the soap that removes the virus particles.[26] Rhinoviruses can live up to 3 hours outside the body on the skin or objects.[8]
In 2002, the Centers for Disease Control and Prevention recommended alcohol-based hand gels as an effective method for reducing infectious viruses on the hands of health care workers.[27] Alcohol-based hand sanitizer however does not completely eliminate the cold-causing rhinovirus.[28] Neither soap and water nor alcohol gels provide residual protection from re-infection.
The common cold is caused by a large variety of viruses, which mutate quite frequently during reproduction, resulting in constantly changing virus strains. Thus, successful immunization is highly improbable.
Probiotics in children 3 – 5 years old were found effective in decreases cold symptoms when taken over 6 months.[29]
Treatment
![](http://upload.wikimedia.org/wikipedia/commons/thumb/7/73/Pneumonia_strikes_like_a_man_eating_shark.jpg/220px-Pneumonia_strikes_like_a_man_eating_shark.jpg)
The common cold usually resolves spontaneously in 7 to 10 days, but some symptoms can last for up to three weeks.[4] There are no medications or herbal remedies proven to shorten the duration of illness. Treatment is symptomatic support usually via providing analgesics for fever, headache and myalgia, nasal decongestants and antihistamines for nasal congestion and runniness, and lozenges for sore throat.
Conservative management
The National Institute of Allergy and Infectious Diseases suggests getting plenty of rest, drinking fluids to maintain hydration, gargling with warm salt water, using cough drops, throat sprays, or over-the-counter pain or cold medicines.[8] Saline nasal drops may help alleviate congestion.[30]
Treatments that help alleviate symptoms include analgesics ( such as NSAIDs[31] ), decongestants, and cough suppressants,[citation needed] first-generation antihistamines such as brompheniramine, chlorpheniramine, diphenhydramine and clemastine (which reduce mucus gland secretion and thus combat blocked/runny noses but also may make the user drowsy). Second-generation antihistamines do not have a useful effect on colds.[citation needed]
Vitamin C in normal or mega doses has not been shown to be beneficial in a normal population for the prevention or treatment of the common cold. It however might be beneficial in people exposed to periods of severe physical exercise or cold environments.[32]
Various cold medicines exist however little evidence suggest they are any more effective than simple analgesics. They include antitussives, antihistamines and decongestants usually in combination with an analgesic. They are not recommended for use in children because evidence does not support their effectiveness and there are concerns of harm.[33]
Antibiotics
Antibiotics only target bacteria and thus do not have any beneficial effect against the common cold.
Antivirals
There are no approved antiviral drugs for the common cold.
Alternative treatments
Many alternative treatments are used to treat the common cold. None, however, are supported by solid scientific evidence.[25] Some alternative treatments, like echinacea, have not been shown to have any effects on the frequency of infection, the duration of infection, or the severity of symptoms of the common cold.[34][35] Other alternative treatments which similarly lack solid scientific evidence include calendula[36], ginger[37], garlic[38] and vitamin C supplements.[39]
Prognosis
Although the disease is generally mild and self-limiting, patients with common colds often seek professional medical help, use over-the-counter drugs, and may miss school or work days. The annual cumulative societal cost of the common cold in developed countries is considerable in terms of money spent on remedies, and hours of lost productivity.
There are no antiviral drugs approved to treat or cure the infection; all medications used are palliative and treat symptoms only. Alternative treatments such as vitamin C, echinacea, and zinc have been proposed but none of them has been shown to decrease the duration of the illness,[25] and thus none of them is approved by the Food and Drug Administration or European Medicines Agency. To prevent infection, washing or disinfecting[40] hands has been found effective, as this minimizes person-to-person transmission of the virus.
Epidemiology
Upper respiratory tract infections are the most common infectious diseases among adults, who have two to four respiratory infections annually.[41] Children may have six to ten colds a year (and up to 12 colds a year for school children).[8][42] In the United States, the incidence of colds is higher in the fall (autumn) and winter, with most infections occurring between September and April. The seasonality may be due to the start of the school year, or due to people spending more time indoors (thus in closer proximity with each other) increasing the chance of transmission of the virus.[8]
History
![](http://upload.wikimedia.org/wikipedia/commons/thumb/4/47/Definition_of_a_Cold_by_Benjamin_Franklin_Page_1.jpg/220px-Definition_of_a_Cold_by_Benjamin_Franklin_Page_1.jpg)
The name "common cold" came into use in the 16th century, due to the similarity between its symptoms and those of exposure to cold weather.[43] Norman Moore relates in his history of the Study of Medicine that James I continually suffered from nasal colds, which were then thought to be caused by polypi, sinus trouble, or autotoxaemia.[44]
In the 18th century, Benjamin Franklin considered the causes and prevention of the common cold. After several years of research he concluded: "People often catch cold from one another when shut up together in small close rooms, coaches, etc. and when sitting near and conversing so as to breathe in each other's transpiration." Although viruses had not yet been discovered, Franklin hypothesized that the common cold was passed between people through the air. He recommended exercise, bathing, and moderation in food and drink consumption to avoid the common cold.[45] Franklin's theory on the transmission of the cold was confirmed some 150 years later.[46]
Common Cold Unit
In the United Kingdom, the Common Cold Unit was set up by the Medical Research Council in 1946. The unit worked with volunteers who were infected with various viruses.[47] The rhinovirus was discovered there.[48] In the late 1950s, researchers were able to grow one of these cold viruses in a tissue culture, as it would not grow in fertilized chicken eggs, the method used for many other viruses. In the 1970s, the CCU demonstrated that treatment with interferon during the incubation phase of rhinovirus infection protects somewhat against the disease[49], but no practical treatment could be developed. The unit was closed in 1989, two years after it completed research of zinc gluconate lozenges in the prophylaxis and treatment of rhinovirus colds, the only successful treatment in the history of the unit.[50]
Social and cultural
Economic cost
![](http://upload.wikimedia.org/wikipedia/commons/thumb/3/35/The_Cost_Of_The_Common_Cold_%26_Influenza.jpg/220px-The_Cost_Of_The_Common_Cold_%26_Influenza.jpg)
Template:Globalize/USA In the United States, the common cold leads to 75 to 100 million physician visits annually at a conservative cost estimate of $7.7 billion per year. Americans spend $2.9 billion on over-the-counter drugs and another $400 million on prescription medicines for symptomatic relief.[41][52]
More than one-third of patients who saw a doctor received an antibiotic prescription, which has implications for antibiotic resistance from overuse of such drugs.[52]
An estimated 22 to 189 million school days are missed annually due to a cold. As a result, parents missed 126 million workdays to stay home to care for their children. When added to the 150 million workdays missed by employees suffering from a cold, the total economic impact of cold-related work loss exceeds $20 billion per year.[8][41][52]
Research
Biota Holdings are developing a drug, currently know as BTA798, which targets rhinovirus. The drug has recently successfully completed Phase IIa clinical trials.[53][54]
ViroPharma and Schering-Plough are developing an antiviral drug, pleconaril, that targets picornaviruses, the viruses that cause the majority of common colds. Pleconaril has been shown to be effective in an oral form.[55][56] Schering-Plough is developing an intra-nasal formulation that may have fewer adverse effects.[57]
Researchers from University of Maryland, College Park and University of Wisconsin–Madison have mapped the genome for all known virus strains that cause the common cold.[57]
See also
References
- ^ Macnair, Dr. Trisha. "The Common Cold". bbc.co.uk Health. BBC. Retrieved 2009-09-30.
- ^ a b c d e f g h i j k Eccles R (2005). "Understanding the symptoms of the common cold and influenza". Lancet Infect Dis. 5 (11): 718–25. doi:10.1016/S1473-3099(05)70270-X. PMID 16253889.
{{cite journal}}
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ignored (help) - ^ Nordenberg, Tamar (1999). "Colds and Flu: Time Only Sure Cure". Food and Drug Administration. Retrieved 2007-06-13.
{{cite web}}
: Unknown parameter|month=
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External links
- Cold and flu advice (NHS Direct)