{{DiseaseDisorder infobox |
Name = Acute nasopharyngitis|
ICD10 = |
ICD9 = |
DiseasesDB = 31088 |
MedlinePlus = 000678 |
eMedicineSubj = med |
eMedicineTopic = 2339 |
MeshID = D003139 |
}}
Acute viral nasopharyngitis, or
acute coryza, usually known as the
common cold, is a highly contagious,
viral infectious disease of the upper
respiratory system, primarily caused by
picornaviruses or
coronaviruses.
Common symptoms are
sore throat,
runny nose,
nasal congestion,
sneezing and
cough; sometimes accompanied by
muscle aches,
fatigue,
malaise,
headache,
muscle weakness, or
loss of appetite.
Fever and extreme
exhaustion are more usual in
influenza. The symptoms of a cold usually resolve after about one week, but can last up to 14 days. Symptoms may be more severe in infants and young children. 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 cumulative societal cost of the common cold in the United States is billions of dollars.
No
vaccines are available: the primary method to prevent infection is hand-washing to minimize person-to-person transmission of the virus. There are no
antiviral drugs approved to treat or cure the infection. Most available medications are
palliative and treat symptoms only.
Megadoses of vitamin C, preparations from
echinacea, and
zinc gluconate have been studied as treatments for the common cold although none have been approved by the
Food and Drug Administration or
European Medicines Agency.
Pathology
Epidemiology
Upper respiratory tract infections are the most common infectious diseases among adults who have two to four respiratory infections annually.
Transmission
The common cold virus is transmitted between people by one of two ways:
through the air from aerosols containing the virus created by coughs or sneezes, or
from contact with the saliva or nasal secretions of an infected person, either directly or from contaminated surfaces.
The infectious period (time during which an infected person can infect others) begins about one day before symptoms begin, and continues for the first five days of the illness. Symptoms, however, are not necessary for viral shedding or transmission, as a percentage of asymptomatic subjects exhibit viruses in nasal swabs.
The virus enters the
cells of the lining of the
nasopharynx (the area between the nose and throat), and rapidly multiplies. The major entry point is normally the nose, but can also be the eyes (in this case drainage into the nasopharynx would occur through the
Nasolacrimal duct).
Symptoms
After initial infection, the viral replication cycle begins within 8 to 12 hours. Symptoms can occur shortly thereafter, and usually peak within 2 to 3 days after infection.
The first indication of a cold is often a
sore or scratchy throat. Other common symptoms are
runny nose,
congestion,
sneezing and
cough. These are sometimes accompanied by
muscle aches,
fatigue,
malaise,
headache,
weakness, or
loss of appetite. Colds occasionally cause
fever and can sometimes lead to extreme exhaustion. (However, these symptoms are more usual in
influenza, and can differentiate the two infections.) The symptoms of a cold usually resolve after about one week, but can last up to 14 days, with a cough lasting longer than other symptoms. Symptoms may be more severe in infants and young children, and may include fever.
The economic cost of the common cold
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.
More than one-third of patients who saw a doctor received an antibiotic prescription, which not only contributes to unnecessary costs ($1.1 billion annually on an estimated 41 million antibiotic prescriptions in the United States), but also has implications for antibiotic resistance from overuse of such drugs.
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.
Prevention
The best way to avoid a cold is to avoid close contact with existing sufferers; to wash hands thoroughly and regularly; and to avoid touching the mouth and face. Anti-bacterial soaps have no effect on the cold virus; it is the mechanical action of hand washing that removes the virus particles.
[{{cite web]
| publisher = Canadian Health Network
| url = http://www.canadian-health-network.ca/servlet/ContentServer?cid=1138724359598&pagename=CHN-RCS/CHNResource/CHNResourcePageTemplate&c=CHNResource | title = The importance of handwashing for your health
}}
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.
[{{cite journal]
| last = Boyce
| first = John M.
| coauthors = Didier Pittet
| 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
| journal = Morbidity and Mortality Weekly Report
| date = 2002-10-25
| volume = 51
| issue = RR-16
| url = http://www.cdc.gov/mmwr/PDF/rr/rr5116.pdf
| format = pdf
| pmid = 12418624
| accessdate = 2007-06-21
}}
As with hand washing with soap and water, alcohol gels provide no 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.
Treatment
As there is no medically proven and accepted medication directly targeting the causative agent, there is no cure for the common cold. Treatment is limited to symptomatic supportive options, maximizing the comfort of the patient, and limiting complications and harmful sequelae. The most reliable treatment is a combination of fluids and plenty of rest.
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.
Antibiotics
Antibiotics do not have any beneficial effect against the common cold. Their use in cases of common cold infection is ineffective and may contribute to
antibiotic resistance of
bacteria present in the patient's body.
Antivirals
There are no approved
antiviral drugs for the common cold.
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.
[{{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 =
}}[{{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
}}
Schering-Plough is developing an
intra-nasal formulation that may have fewer adverse effects.
[{{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
}}
Over-the-counter symptom medicines
There are a number of effective treatments which, rather than treat the viral infection, focus on relieving the symptoms. For some people, colds are relatively minor inconveniences and they can go on with their daily activities with tolerable discomfort. This discomfort has to be weighed against the price and possible side effects of the remedies.
analgesics such as aspirin or paracetamol (acetaminophen), as well as localised versions targeting the throat (often delivered in lozenge form)
nasal decongestants such as pseudoephedrine or oxymetazoline which reduce the inflammation in the nasal passages by constricting local blood vessels
cough suppressants such as dextromethorphan which suppress the cough reflex.
first-generation anti-histamines 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 anti-histamines do not have a useful effect on colds.
Echinacea
Echinacea, commonly called coneflowers, are plants with large showy heads of composite flowers. They are herbaceous, drought-tolerant perennial plants, native to North America, growing to 1 or 2 m in height. Echinacea is used in herbal preparations used to treat the common cold.
Although there have been scientific studies evaluating echinacea, its effectiveness has not been convincingly demonstrated. For example, a peer-reviewed
clinical study published in the
New England Journal of Medicine concluded that "…extracts of E. angustifolia root, either alone or in combination, do not have clinically significant effects on rhinovirus infection or on the clinical illness that results from it."
{{cite journal
| last = Turner
| first = Ronald B.
| coauthors = Rudolf Bauer, Karin Woelkart, Thomas C. Hulsey, J. David Gangemi,
| date = 2005-07-28
| title = An Evaluation of Echinacea angustifolia in Experimental Rhinovirus Infections
| journal = New England Journal of Medicine
| volume = 353
| issue = 4
| pages = 341–348
| url = http://content.nejm.org/cgi/content/abstract/353/4/341
| accessdate = 2007-02-12
}}[{{cite news]
| last = Kolta
| first = Gina
| title = Study Says Popular Herb Has No Effect on Colds
| work = New York Times
| date = 2006-07-28
| url = http://query.nytimes.com/gst/fullpage.html?sec=health&res=9805E5DC103FF93BA15754C0A9639C8B63
| accessdate = 2007-07-07
}}
Recent randomized, double-blind, placebo-controlled studies in adults have not shown a beneficial effect of echinacea on symptom severity or duration of the cold.
A structured review of 9 placebo controlled studies suggested that the effectiveness of echinacea in the treatment of colds has not been established.
[{{cite journal | author = Caruso TJ, Gwaltney JM | title = Treatment of the common cold with echinacea: a structured review]
| journal = Clin. Infect. Dis. | volume = 40 | issue = 6 | pages = 807-10 | year = 2005 | pmid = 15736012 | doi = 10.1086/428061}}
Conversely, two recent meta-analyses of published medical articles concluded that there is some evidence that echinacea may reduce either the duration or severity of the common cold, but results are not fully consistent. However, there have been no large, randomized placebo-controlled clinical studies that definitively demonstrate either prophylaxis or therapeutic effects in adults.
[{{cite journal]
| last = Shah
| first = Sachin A
| coauthors = S. Sander, C. White, M. Rinaldi, C. Coleman
| year = 2007
| month = July
| title = Evaluation of echinacea for the prevention and treatment of the common cold: a meta-analysis
| journal = The Lancet Infectious Diseases
| volume = 7
| issue = 7
| pages = 473-480
| pmid = 17597571
| doi = 10.1016/S1473-3099(07)70160-3
| accessdate = 2007-07-07
}}[{{cite journal]
| last = Linde
| first = K
| coauthors = Barrett B, Wölkart K, Bauer R, Melchart D.
| year = 2006
| month = January
| title = Echinacea for preventing and treating the common cold
| journal = Cochrane database of systematic reviews
| ISSN = 1469-493X
| pmid = 16437427
| accessdate = 2007-07-07
}}
A randomized, double-blind, placebo-controlled study in 407 children of ages ranging from 2 to 11 years showed that echinacea did not reduce the duration of the cold, or reduce the severity of the symptoms.
[{{cite journal]
| author = Taylor JA, Weber W, Standish L, Quinn H, Goesling J, McGann M, Calabrese C
| title = Efficacy and safety of echinacea in treating upper respiratory tract infections in children: a randomized controlled trial
| journal = JAMA
| volume = 290
| issue = 21
| pages = 2824-30
| year = 2003
| pmid = 14657066
| doi = 10.1001/jama.290.21.2824
}}
Most authoritative sources consider the effect of echinacea on the cold unproven.
Reported adverse effects of echinacea include
nausea,
dizziness,
dyspnea,
rash,
dermatitis,
pruritis, and
hepatotoxicity. These tend to be infrequent, mild and transient. Echinacea should not be taken with hepatotoxic drugs or
immunosuppressants.
[{{cite web]
| last = Cheeseman
| first = Mark
| title = Echinacea
| work = Complementary Medicines Summary
| publisher = UK Medicines Information, National Health Service
| date = 2002-12-13
| url = http://www.ukmi.nhs.uk/Med_info/documents/EchinaceaCMS.pdf
| type = pdf
| accessdate = 2007-07-07
}}
Forty-five percent of retail echinacea products failed quality testing by an independent consumer testing laboratory, due to either high lead levels, or low plant chemicals.
[{{cite web]
| url = http://www.consumerlab.com/results/echinacea.asp
| title = Product Review: Echinacea
| accessdate = 2007-08-02
| author =
| authorlink =
| coauthors =
| date = 2004-03-18
| format =
| work =
| publisher = ConsumerLab.com, LLC
| pages =
| language =
| archiveurl =
| archivedate =
| quote =
}}
Other
Vitamin C
A well known supporter of the theory that
Vitamin C megadosage prevented infection was Nobel Prize winner
Linus Pauling,
[Pauling L, The Significance of the Evidence about Ascorbic Acid and the Common Cold, Proc Natl Acad Sci U S A. 1971 November; 68(11): 2678–2681. ] who wrote the bestseller ''Vitamin C and the Common Cold''.
A
meta-analysis published in 2005 found that "the lack of effect of prophylactic vitamin C supplementation on the incidence of common cold in normal populations throws doubt on the utility of this wide practice".
A follow-up meta-analysis supported these conclusions:
Prophylactic use "...of vitamin C has no effect on common cold incidence ... but reduces the duration and severity of common cold symptoms slightly, although the magnitude of the effect was so small its clinical usefulness is doubtful. Therapeutic trials of high doses of vitamin C ... starting after the onset of symptoms, showed no consistent effect on either duration or severity of symptoms. ... More therapeutic trials are necessary to settle the question, especially in children who have not entered these trials."
Most of the studies showing little or no effect employ doses of ascorbate such as 100 mg to 500 mg per day, considered "small" by vitamin C advocates. Equally important, the plasma half life of high dose ascorbate above the baseline, controlled by renal resorption, is approximately 30 minutes,
[Padayatty SL et al, Vitamin C Pharmacokinetics: Implications for Oral and Intravenous Use, Ann Intern Med. 2004 Apr 6;140(7):533-7. ][Researchers Question Government Recommended Daily Allowance (RDA) for vitamin C, PR Web, July 7, 2004 ] which implies that most high dose studies have been methodologically defective and would be expected to show a minimum benefit. Clinical studies of divided dose supplementation, predicted on pharmacological grounds to be effective, have only rarely been reported in the literature.
Because vitamin C is metabolized to
oxalic acid in the body, some scientists have long speculated that high doses may contribute to the development of
kidney stones.
The U.S.
Institute of Medicine recommends a daily requirement of 45mg to 90mg of vitamin C for adults, up to 85mg for pregnant women and up to 120mg for nursing mothers,
while the
European Commission Health and Consumer Protection DG recommends 40mg/d for adults (50mg/d and 60mg/d for pregnant women and nursing mothers, respectively).
Zinc preparations
Zinc is an essential element, necessary for sustaining life. Recommended daily intake has been established and results of zinc deficiency and toxicity have been well characterized.
Zinc acetate and
zinc gluconate have been tested as potential treatments for the common cold, in various dosage form including nasal sprays, nasal gels, and lozenges.
Some studies have shown some effect of zinc preparations on the duration of the common cold, but conclusions are diverse.
Approximately half of studies demonstrate efficacy. Even studies that show clinical effect have not demonstrated the mechanism of action.
The studies differ in the salt used, concentration of the salt, dosage form, and formulation, and some suffer from defects in design or methods. For example, there is evidence that the potential efficacy of zinc gluconate lozenges may be affected by other food acids (
citric acid,
ascorbic acid and
glycine) present in the lozenge.
Furthermore, interpretation of the results depends on whether concentration of total zinc or ionic zinc is considered.
There are concerns regarding the safety of long-term use of cold preparations in an estimated 25 million persons who are
haemochromatosis heterozygotes.
Use of high doses of zinc for more than two weeks may cause
copper depletion, which leads to
anemia.
Other adverse events of high doses of zinc include
nausea,
vomiting gastrointestinal discomfort,
headache,
drowsiness, unpleasant taste, taste distortion, abdominal cramping, and
diarrhea.
Some users of nasal spray applicators containing zinc have reported temporary or permanent loss of sense of
smell.
Although widely available and advertised in the United States as dietary supplements or homeopathic treatments, the safety and efficacy of zinc preparations have not been evaluated or approved by the
Food and Drug Administration. Authoritative sources consider the effect of zinc preparations on the cold unproven.
Steam inhalation
Many people believe that steam inhalation reduces symptoms of the cold.
[{{cite journal]
| author = Braun BL, Fowles JB, Solberg L, Kind E, Healey M, Anderson R
| title = Patient beliefs about the characteristics, causes, and care of the common cold: an update
| journal = The Journal of Family Practice
| volume = 49
| issue = 2
| pages = 153-6
| year = 2000
| pmid = 10718693
| doi =
}}
However, a
double-blind, placebo-controlled, randomized study found no effect of steam inhalation on cold symptoms.
[{{cite journal]
| last = Forstall
| first = G. J.
| coauthors = M. L. Macknin, B. R. Yen-Lieberman, S. V. Medendrop
| date = 13 April 1994
| title = Effect of inhaling heated vapor on symptoms of the common cold
| journal = Journal of the American Medical Association (JAMA)
| volume = 271
| issue = 14
| url = http://jama.ama-assn.org/cgi/content/abstract/271/14/1109
| accessdate = 2007-03-29
}} A scientific review of medical literature concluded that "there is insufficient evidence to support the use of steam inhalation as a treatment."
[{{cite journal]
| last = Singh
| first = M
| date = 19 April 2004
| title = Heated, humidified air for the common cold
| journal = The Cochrane Database of Systematic Reviews
| issue = 2
| url = http://www.mrw.interscience.wiley.com/cochrane/clsysrev/articles/rel0002/CD001728/frame.html
| accessdate = 2007-03-29
}} There have been reports of children being badly burned when using steam inhalation to alleviate cold symptoms leading to the recommendation to "...start discouraging patients from using this form of home remedy, as there appears to be no significant benefit from steam inhalation."
[{{cite journal]
| quotes =
| author = MA Akhavani
| coauthors = RHJ Baker
| date = 1 July 2005
| title = Steam inhalation treatment for children
| journal = British Journal of General Practice
| volume = 55
| url = http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1472796
| accessdate = 2007-03-29
}}
Chicken soup
In the twelfth century, Moses
Maimonides wrote, "
Chicken soup...is recommended as an excellent food as well as
medication."
[{{cite journal]
| last = Rosner
| first = F
| year = 1980
| month = October
| title = Therapeutic efficacy of chicken soup
| journal = Chest
| volume = 78
| issue = 4
| pages = 672-674
| pmid = 7191367
| accessdate = 2007-07-08
}}
Since then, there have been numerous reports that chicken soup alleviates the symptoms of the common cold. Even usually staid medical journals have published
tongue-in-cheek humorous articles on the alleged medicinal properties of chicken soup.
[{{cite journal]
| last = Rennard
| first = Barbara O.
| coauthors = Ronald F. Ertl, Gail L. Gossman, Richard A. Robbins, Stephen I. Rennard
| date =
| year = 2000
| month = October
| title = Chicken Soup Inhibits Neutrophil Chemotaxis In Vitro
| journal = Chest
| volume = 118
| issue = 4
| pages = 1150-1157
| pmid = 11035691
| accessdate = 2007-07-08
}}[{{cite journal]
| last = Caroline
| first = NL.
| coauthors = H Schwartz
| year = 1975
| month = February
| title = Chicken soup rebound and relapse of pneumonia
| journal = Chest
| volume = 67
| issue = 2
| pages = 215-216
| pmid = 1090422
| accessdate = 2007-07-08
}}[{{cite journal]
| last = Ohry
| first = Abraham
| coauthors = Jenni Tsafrir
| date = 1999-12-14
| title = Is chicken soup an essential drug?
| journal = Canadian Medical Association Journal
| volume = 161
| issue = 12
| pmid = 10624412
| accessdate = 2007-07-08
}}
However, the efficacy of chicken soup has not been studied in any rigorous clinical trials. Nevertheless, hot chicken soup is nutritious and easy to eat, aids in rehydration, and provides a temporary feeling of relief.
History
Colds have existed since ancient times, being known in
ancient Egypt, where there were
hieroglyphs representing the cough and the common cold. The Greek physician
Hippocrates gave a description of the disease in the
5th century BC. The common cold was also known among the ancient
American Indian,
Aztec, and
Maya civilizations. A mixture of
chili pepper,
honey, and
tobacco was one common Aztec treatment for colds.
In the
18th century,
John Wesley wrote a book about curing diseases; it advised against cold baths, stating that chilling causes the common cold. The work was widely reprinted in the
19th century. Another book by
William Buchan in the 18th century also gave wet feet and clothes as the cause of the common cold.
The idea that microscopic infectious agents cause disease only arose in the second half of the
19th century.
Initially,
bacteria were suspected to be the cause of the common cold, and
vaccines were produced based on this theory; these were still prescribed in the
1950s.
Viruses had been described beginning in the
1890s: infectious agents so small that they could pass through all filters and could not be seen under a microscope. In
1914,
Walter Kruse, a professor in
Leipzig,
Germany, showed that viruses caused the common cold: nose secretions of a cold sufferer were diluted, filtered, and introduced into the noses of volunteers, producing colds in about half of the cases. These findings were not widely accepted, until they were repeated in the
1920s by
Alphonse Dochez, first in
chimpanzees, and then in human volunteers using a
double-blind setup. Nevertheless, in 1932 a major textbook on the common cold by
David Thomson still presented bacteria as the most likely cause.
In the
United Kingdom, the
Common Cold Unit was set up by the civilian
Medical Research Council in 1946 . The unit worked with volunteers who were infected with various viruses. The rhinovirus was discovered there. 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, but no practical treatment could be developed. The unit was closed in 1989, just two years after it demonstrated the benefit of zinc gluconate lozenges in the prophylaxis and treatment of rhinovirus colds.
[{{cite journal]
| journal = J Antimicrob Chemother.
| Year = 1987
| month = December
| volume = 20
| issue = 6
| pages = 893-901
| title = Prophylaxis and treatment of rhinovirus colds with zinc gluconate lozenges
| last = Al-Nakib
| first = W
| coauthors = Higgins PG, Barrow I, Batstone G, Tyrrell DA.
| pmid = 3440773
}}
Effect of exposure to cold weather on incidence of common colds
Although common colds are seasonal, with more occurring during winter, there is no evidence that short-term exposure to cold weather or direct chilling increases susceptibility to infection.
With respect to the causation of cold-like ''symptoms'', researchers at the Common Cold Centre at the
Cardiff University conducted a study to "test the hypothesis that acute cooling of the feet causes the onset of common cold symptoms."
In the experiment, 28.8% of a group of 90 people who sat with their feet in ice-cold water for 20 minutes twice a day for four or five days reported cold symptoms within five days of the procedure, while just 8.8% of a control group of 90 people who were not similarly exposed reported cold symptoms. 14.4% of those who were chilled reported believing they had a cold, compared to just 5.6% of the control group. The study measured the subjects' self-reported cold symptoms, and belief they had a cold, but not whether an actual respiratory infection developed. It concludes that the onset of common cold ''symptoms'' can be caused by acute chilling of the feet, but that "further studies are needed to determine the relationship of symptom generation to any respiratory infection."
References