Causes and Symptoms (Magill’s Medical Guide, Sixth Edition)
One of the reasons that no cure has ever been found for the common cold is that it is caused by literally hundreds of different viruses. More than two hundred distinct strains from eight genera have been identified, and no doubt more will be discovered. Infection by one of these viruses may confer immunity to it, but there will still be scores of others to which that individual is not immune. The common cold is usually restricted to the nose and surrounding areas—hence its medical name, rhinitis (rhin meaning “nose” and itis meaning “inflammation”).
Children get the most colds, averaging six to eight per year until they are six years old. From that age, the number diminishes until, for adults, the rate is three to five colds per year. Colds and related respiratory diseases are the largest single cause of lost workdays and school days. Colds and related respiratory diseases are probably the world’s most expensive illnesses. In the United States, about a million and a half person-years are lost from work each year; this figure accounts for one-half of all absences. Worldwide, the costs of lost workdays, medications, physician’s visits, and the complications that may require extensive medical care are incalculable.
Among the virus types that cause the common cold are rhinovirus, coronavirus, influenza virus, parainfluenza virus, enterovirus, adenovirus, respiratory syncytial virus, and...
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Treatment and Therapy (Magill’s Medical Guide, Sixth Edition)
The nose is the first barrier of defense against the bacteria and viruses that cause upper respiratory infections. The nasal cavity is lined with a thin coating of mucus, a thick liquid that is constantly replenished by the mucous glands. Inner nasal surfaces are filled with tiny hairs, or cilia. Dust, bacteria, and other foreign matter are trapped by the mucus and moved by the cilia toward the nasopharynx to be expectorated or swallowed.
The blood vessels in the nasopharyngeal bed respond automatically to stimulation from the brain. Certain stimuli cause the vessels to constrict, widening air passages and at the same time reducing the flow of mucus. Other stimuli, such as those that are sent in response to a viral infection, allergen, or other irritant, cause blood vessels to dilate and increase the flow of mucus. Nasal passages become swollen, and airways are blocked.
The mucus-covered lining of the nasal passages contains various substances that help ward off infection and irritation by allergens. Lysozyme (lyso meaning “dissolution” and zyme from “enzyme,” a catalyst that promotes an activity) attacks the cell walls of certain bacteria, killing them. It also attacks pollen granules. Mucus also contains glycoproteins that temporarily inhibit the activity of viruses. Mucus has small amounts of the antibodies immunoglobulin IgA and IgC that also may inhibit the activity of invading...
(The entire section is 1166 words.)
Perspective and Prospects (Magill’s Medical Guide, Sixth Edition)
Viruses are among the most intriguing and baffling challenges to medical science. Great progress has been made in preventing some virus diseases, such as by immunization against smallpox and hepatitis B. There has been only limited success, however, in finding agents to cure viral diseases, and so far nothing has been found to prevent or cure the common cold. Vaccines have been developed against certain rhinoviruses, and no doubt many more could be developed. Yet because the common cold is caused by so many different types of virus—more than two hundred—and vaccines against one virus are not necessarily effective against others, it is questionable whether such vaccines would ever be useful. A helpful vaccine would be one that could immunize against an entire family of viruses such as rhinoviruses or coronaviruses, the two leading causes of the common cold.
The search goes on for agents to cure the common cold. Substances, such as interferons, have been found that are effective against a wide range of viruses. One of the interferons was used by the British Medical Research Council’s Common Cold Unit. Those researchers reported that interferon applied as an intranasal spray was highly effective in protecting subjects from cold infection. After some years, however, experimentation with interferon in the common cold was abandoned because the agent had significant side effects, nasal congestion among them....
(The entire section is 345 words.)
For Further Information: (Magill’s Medical Guide, Sixth Edition)
American Pharmaceutical Association. Handbook of Nonprescription Drugs. 15th ed. Washington, D.C.: Author, 2006. The section on drugs for colds, coughs, and allergies contains a thorough background discussion of these conditions. All major over-the-counter medications are listed.
Biddle, Wayne. A Field Guide to Germs. 2d ed. New York: Anchor Books, 2002. This comprehensive book is easily accessible to the nonspecialist and includes a discussion of nearly every virus, bacterium, and fungus known to cause human and nonhuman animal disease. The history of the microbe and the treatment of diseases are included.
Gallo, Robert. Virus Hunting. New York: Basic Books, 1991. Gallo gives a good general account of viruses—how they live and how modern medical science is trying to combat them.
Kimball, Chad T. Colds, Flu, and Other Common Ailments Sourcebook. Detroit, Mich.: Omnigraphics, 2001. A comprehensive guide for general readers covering treatment issues and controversies surrounding common ailments and injuries. Includes discussions on ailments of the nose, throat, lungs, ears, eyes, and head; common injuries; alternative therapies; choosing a doctor; and buying drugs and finding health information online.
Litin, Scott C., ed. Mayo Clinic Family Health Book. 4th ed. New York: HarperResource, 2009. One of the most thorough and accessible medical texts for...
(The entire section is 286 words.)
Common Cold (Encyclopedia of Medicine)
The common cold is a viral infection of the upper respiratory system, including the nose, throat, sinuses, eustachian tubes, trachea, larynx, and bronchial tubes. Although over 200 different viruses can cause a cold, 300% are caused by a group known as rhinoviruses. Almost all colds clear up in less than two weeks without complications.
Colds, sometimes called rhinovirus or coronavirus infections, are the most common illness to strike any part of the body. It is estimated that the average person has more than 50 colds during a lifetime. Anyone can get a cold, although pre-school and grade school children catch them more frequently than adolescents and adults. Repeated exposure to viruses causing colds creates partial immunity.
Although most colds resolve on their own without complications, they are a leading cause of visits to the doctor and of time lost from work and school. Treating symptoms of the common cold has given rise to a multi-million dollar industry in over-the-counter medications.
Cold season in the United States begins in early autumn and extends through early spring. Although it is not true that getting wet or being in a draft causes a cold (a person has to come in contact with the virus to catch a cold), certain conditions may lead to increased...
(The entire section is 2297 words.)
Common Cold (Encyclopedia of Children's Health)
The common cold, also called a rhinovirus or coronavirus infection, is a viral infection of the upper respiratory system, including the nose, throat, sinuses, eustachian tubes, trachea, larynx, and bronchial tubes. Over 200 different viruses can cause a cold. Almost all colds clear up in less than two weeks without complications.
Cold season in the United States begins in early autumn and extends through early spring. Although it is not true that getting wet or being in a draft causes a cold (a person has to come in contact with the virus to catch a cold), certain conditions may lead to increased susceptibility. These include:
- fatigue and overwork
- emotional stress
- poor nutrition
- living or working in crowded conditions
Although most colds resolve on their own without complications, they are a leading cause of visits to the doctor and of time lost from work and school. Treating symptoms of the common cold has given rise in the United States to a multi-million dollar industry in over-the-counter medications.
Colds make the upper respiratory system less...
(The entire section is 2415 words.)
Common Cold (Encyclopedia of Alternative Medicine)
The common cold is a viral infection of the upper respiratory system, which includes the nose, throat, sinuses, eustachian tubes, trachea, larynx, and bronchial tubes. Although more than 200 different viruses can cause a cold, 300% are caused by a group known as rhinoviruses. Almost all colds clear up in less than two weeks without complications.
Colds, sometimes called rhinovirus or coronavirus infections, are the most common illness to strike any part of the body. It is estimated that the average person has more than 50 colds during a lifetime. Anyone can get a cold, although preschool and grade school children catch them more frequently than adolescents and adults. Repeated exposure to viruses causing colds creates partial immunity.
Although most colds resolve on their own without complications, they are a leading cause of visits to the doctor and of time lost from work and school. Treating symptoms of the common cold has given rise to a multimillion dollar industry in over-the-counter medications, yet none of these medications are actually anti-viral to the rhinovirus.
Cold season in the United States begins in early autumn and extends through early spring. Although it is not true that getting wet or being in a draft causes a cold (a person has to come in...
(The entire section is 2530 words.)
Common Cold (Encyclopedia of Nursing & Allied Health)
The common cold is a viral infection of the upper respiratory system, including the nose, throat, sinuses, eustachian tubes, trachea, larynx, and bronchial tubes. Although over 200 different viruses can cause a cold, 300% are caused by a group of viruses known as rhinoviruses. Almost all colds clear up in less than two weeks without complications.
Colds, sometimes called rhinovirus or coronavirus infections, are common, frequently occurring illnesses. It is estimated that the average person has more than 50 colds during a lifetime. Anyone can get a cold, although preschool and grade school children catch them more frequently than adolescents and adults because they have not been exposed to the cold viruses and developed immunity. Repeated exposure to the viruses that cause colds creates partial immunity.
Although most colds resolve on their own without complications, they are a leading cause of visits to the doctor and of time lost from work and school. Treating symptoms of the common cold has given rise to a multi- million dollar industry in over-the-counter medications.
Cold season in the United States begins in early autumn and extends through early spring. Colds occur more frequently during this period because people tend to spend more time indoors where it is easier for viruses to spread from one person to another. Although it is not true that getting wet or being in a draft causes a cold (a person has to come in contact with the virus to catch a cold), certain conditions may lead to increased susceptibility. These include:
- fatigue and overwork
- emotional stress
- poor nutrition
- living or working in crowded conditions
Colds make the upper respiratory system less resistant to bacterial infection. Secondary bacterial infection may lead to otitis media (middle ear infection), bronchitis, pneumonia, sinus infection, or strep throat. Patients with chronic lung disease, asthma, diabetes, or a weakened immune system are more likely to develop these complications.
Causes and symptoms
Colds are caused by more than 200 different viruses. The most common groups are rhinoviruses and coronaviruses. Different viruses are more infectious at different seasons of the year, but determining the exact virus causing the cold is not important for purposes of treatment.
People with colds are contagious during the first two to four days of the infection. Colds pass from person to person in several ways. When an infected person coughs, sneezes, or speaks, tiny fluid droplets containing the virus are expelled. If these are inhaled by others, the virus may establish itself in their noses and airways.
Colds can also be passed through direct contact. If a person with a cold touches his runny nose or watery eyes, then shakes hands with another person, the virus is transferred to the uninfected person. When the uninfected person touches his mouth, nose, or eyes, the virus is transported to an environment where it can reproduce and produce symptoms of illness.
Finally, cold viruses can be spread through inanimate objects such as doorknobs, telephones, or toys that become contaminated with the virus. This is a common method of viral transmission in childcare centers. When a child with a cold touches his runny nose, then plays with a toy, the virus may be transferred to the toy. When another child plays with the toy a short time later, he may pick up the virus on his hands. When the second child touches his contaminated hands to his eyes, nose, or mouth the virus is once again in an environment conducive to replication.
Once acquired, the cold virus attaches itself to the mucosal lining of the nasal passages and sinuses. This causes the infected cells to release a chemical called histamine. Histamine increases blood flow to the infected cells, causing swelling, congestion, and increased mucus production. One to three days following infection, the affected individual begins to experience cold symptoms.
The first cold symptoms are sore throat, runny nose, and sneezing. The initial discharge from the nose is clear and thin. Later it changes to a thick yellow or greenish discharge. Most adults do not develop a fever when they contract a cold. Young children may develop fevers to 102°F (38.9°C).
Along with a runny nose and fever, symptoms of a cold include coughing, sneezing, nasal congestion, headache, myalgias (muscle aches), chills, sore throat, hoarseness, watery eyes, fatigue, and loss of appetite. The cough that accompanies a cold is usually intermittent and nonproductive (dry).
Most people begin to feel better four to five days after cold symptoms become noticeable. All symptoms are generally gone within ten days, except for a dry cough that may linger for up to three weeks.
Colds increase susceptibility to bacterial infections such as strep throat, middle ear infections, and sinus infections. Individuals with symptoms that do not begin to improve within a week; or those with chest pain, persistent fever (fever for longer than a few days), difficulty breathing, productive cough, skin rash, swollen glands, or whitish spots on the tonsils or throat should consult a health care practitioner. The health care practitioner will determine if these patients have acquired secondary bacterial infections that require treatment with antibiotics.
People who have emphysema, chronic pulmonary disease, diabetes, or a weakened immune systemither from diseases such as AIDS or leukemia, or as the result of immunosuppressive medications (corticosteroids, chemotherapy drugs)hould consult a health care practitioner when they experience cold symptoms. Patients with these chronic health problems are at greater risk for secondary infections.
Colds are readily diagnosed using a focused history and physical examination. There are no laboratory tests readily available to detect or isolate the causative virus. When patients seek medical care, the health care practitioner (physician or mid-level practitioner) may perform a throat culture or blood test to rule out a secondary bacterial infection.
Though viruses cause both colds and influenza (flu), influenza is usually a more serious viral illness. A cold develops gradually over the course of a day or two. Patients may have a runny nose, sneezing, mild sore throat, headache and body aches, but usually they do not have fever or feel completely exhausted. Influenza symptoms develop suddenly. They are similar to cold symptoms, but usually more severe. Patients with influenza generally feel sicker than those with colds because the influenza virus produces symptoms throughout the bodyuscle aches, weakness, fever, and chills.
Allergies also produce rhinitis (runny nose). Symptoms of allergic rhinitisneezing, nasal congestion, and itchy, runny nosere commonly caused by dust mites, animal dander, or indoor molds. Other environmental irritants such as smoke, pollen, pollutants, pesticides, and perfumes may also trigger allergic rhinitis. Allergies are usually more persistent than the common cold. An allergist can perform tests to determine if the persistent cold-like symptoms are attributable to an allergic reaction. Also, some people get a runny nose when they go outside in winter and breathe cold air. This type of runny nose, called vasomotor rhinitis, is not a symptom of a cold.
There are no medicines that will cure the common cold. Given time, the body's immune system will make antibodies to fight the infection, and the cold will resolve without any intervention. Antibiotics are useless against a cold. There are, however, medications to provide symptom relief. Pharmaceutical companies in the United States promote an array of products designed to relieve cold symptoms. Most products contain antihistamines, decongestants, and/or pain relievers.
Antihistamines block the action of the chemical histamine that is produced when the cold virus invades the cells lining the nasal passages. Histamine increases blood flow and causes the cells to swell. Antihistamines relieve the symptoms of sneezing, runny nose, itchy eyes, and congestion. Side effects are dry mouth and drowsiness, especially with the first few doses. Patients should be advised against taking antihistamines if they intend to drive or operate dangerous equipment. The brand names of common over-the-counter antihistamines are Chlor- Trimeton, Dimetapp, Tavist, and Actifed. The generic names of two common antihistamines are chlorpheniramine and diphenhydramine.
Decongestants work to constrict the blood flow to the vessels in the nose. This can shrink the tissue, reduce congestion, and open inflamed nasal passages, making breathing easier. Decongestants can cause patients to feel jittery or prevent them from sleeping. They should not be prescribed for or used by patients with heart disease, high blood pressure, or glaucoma. The brand names of some common decongestants are Neo-Synepherine, Novafed, and Sudafed. The generic names of common decongestants are phenylephrine, phenylpropanolamine, pseudoephedrine, and in nasal sprays naphazoline, oxymetazoline, and xylometazoline.
Many over-the-counter medications are combinations of antihistamines and decongestants. They also may include an ache and pain reliever, such as acetaminophen (Datril, Tylenol, Panadol) or ibuprofen (Advil, Nuprin, Motrin, Medipren), and a cough suppressant (dextromethorphan). Common combination medications include Tylenol Cold and Flu, Triaminic, Sudafed Plus, and Tavist D. Aspirin should not be given to children with colds because of its association with a risk of Reye's syndrome.
Nasal sprays and nose drops also are promoted to relieve nasal congestion. These usually contain a decongestant, but the decongestant can act more quickly and strongly than ones found in pills or liquids because it is applied locally, directly in the nose. Congestion usually returns after a few hours.
Patients may become dependent on nasal sprays and nose drops. If used for a long time, users may suffer withdrawal symptoms when the products are discontinued. This withdrawal condition is called rhinitis medicamentosa. Nasal sprays and nose drops should not be used for more than a few days. Patients should be instructed to adhere to product-specific recommendations about duration and frequency of use.
Individuals have varied reactions to different cold medications and may find some more helpful than others. A medication may be effective initially, then lose some of its effectiveness. Children sometimes react differently from adults. Patients should be cautioned against giving over-the-counter cold remedies to infants without first consulting a health care professional.
Care should be taken not to exceed the recommended dosages, especially when combination medications or nasal sprays are used. Individuals should determine whether they wish to use any of these medications based on their need for symptom relief, since none of them shorten the duration of a cold. Patients confused about the use of over-the-counter cold remedies should be encouraged to seek counsel from a health care practitioner, such as a physician, mid-level practitioner, nurse, or pharmacist.
Along with the optional use of over-the-counter cold remedies, there are some self-care steps that patients can take to ease their discomfort. These include:
- Drinking plenty of fluids, but avoiding acidic juices, which may irritate the throat.
- Gargling with warm salt water (made by adding one teaspoon of salt to 8 oz of water) for a sore throat.
- Not smoking.
- Getting plenty of rest.
- Using a cool-mist room humidifier to ease congestion and sore throat.
- Rubbing Vaseline or other lubricant under the nose to prevent irritation from frequent nose blowing.
- For babies too young to blow their noses, the mucus should be suctioned gently with an infant nasal aspirator. It may be necessary to soften the mucus first with a few drops of salt water.
Many alternative health care practitioners believe that people contract colds because their immune systems are weak. They observe that everyone is exposed to cold viruses, but not everyone becomes ill. The difference seems to be in the ability of the immune system to fight infection. Prevention focuses on strengthening the immune system by eating a healthy diet low in sugars and high in fresh fruits and vegetables, practicing meditation to reduce stress, and getting regular moderate exercise.
There is some scientific evidence that phytochemicals, nutrients found in fruits and vegetables, may act to prevent viral infections such as colds. An herb, Echinacea purpurea, is widely used to prevent and treat colds. It is believed to act as a transient (brief) immunostimulant, however, patients with autoimmune diseases should not use it since continuous use had been linked to immunosuppression.
The use of zinc lozenges every two hours along with high doses of vitamin C is another an alternative therapy. Some alternative practitioners also suggest eliminating dairy products for the duration of the cold because they contend that dairy products encourage production of mucus.
The use of zinc lozenges to treat cold symptoms remains controversial. Some studies evaluating the effectiveness of zinc gluconate lozenges found that using zinc in the first 24 hours after cold symptoms occurred shortened the duration of symptoms. Other studies refuted these findings.
Given time, the body will generate antibodies to the cold. Most colds last a week to ten days, and patients start feeling better within four or five days. Occasionally, a cold will lead to a secondary bacterial infection that causes strep throat, bronchitis, pneumonia, sinus infection, or a middle ear infection. These conditions usually resolve rapidly when treated with the appropriate antibiotic.
Health care team roles
Nearly all health care professionals encounter patients seeking advice about, or treatment for, cold symptoms. Physicians, mid-level practitioners, nurses, pharmacists, and health educators are often called upon to evaluate symptoms, instruct patients in self-care techniques, and reassure them that colds are self-limiting disorders that generally resolve without treatment.
Along with strategies to prevent the spread of cold viruses, it is vitally important for health care professionals to teach patients that antibiotics have no role in the treatment of the common cold. Antibiotics should not be prescribed for colds because, as of 2001, there are no antibiotics effective against the viruses that cause colds. Further, antibiotics should not be prescribed unnecessarily because they can produce side effects such as rash and diarrhea. Another dangerous public health consequence of overuse of antibiotics is the emergence of strains of bacteria that are resistant to these medications.
It is not possible to prevent colds because the viruses that cause colds are common and highly infectious. There are, however, steps individuals can take to reduce their spread. These include:
- Washing hands well and frequently, especially after touching the nose and before handling food.
- Covering the mouth and nose when sneezing.
- Disposing of used tissues properly.
- Avoiding close contact with an infected individual during the first two to four days of their infection.
- Not sharing food, eating utensils, or cups with others.
- Avoiding crowded places where cold germs can spread.
- Eating a healthy diet and getting adequate sleep.
Bronchial tubeshe major airways to the lungs and their main branches.
Coronavirus type of virus that causes respiratory disease and gastroenteritis.
Corticosteroids group of hormones produced naturally by the adrenal gland or manufactured synthetically. They are often used to treat inflammation. Examples include cortisone and prednisone.
Eustachian tube thin tube between the middle ear and the pharnyx. Its purpose is to equalize pressure on either side of the ear drum.
Rhinovirus virus that infects the upper respiratory system and causes the common cold.
Castleman, Michael. "Cold and Flu Therapy." In Nature's Cures. Emmaus, PA: Rodale Press, 1996.
"Colds and Flu." In Alternative Medicine: The Definitive Guide, compiled by the Burton Goldeberg Group. Puyallup, WA: Future Medicine Publishing, 1994.
Pelletier, Kenneth R. The Best Alternative Medicine What Works? What Does Not? New York: Simon & Schuster, 2000.
Silverstein Alvin, et al. Common Cold and Flu (Diseases and People). Springfield, MA: Enslow Publishers, 1996.
"Zinc: A Weapon Against the Commmon Cold?" Mayo Health Oasis. <<a href="http://www.mayohealth.org/mayo/9709/htm/zinc.htm">http://www.mayohealth.org/mayo/9709/htm/zinc.htm>. (9 September 1997).
Cold, Common (World of Microbiology and Immunology)
Dedicated researchers have searched for a cure or even an effective treatment for the common cold (rhinitis) for years. Discovering or constructing the agent that will be universally lethal to all the cold-causing viruses has been fruitless. A drug that will kill only one or two of the viruses would be of little use since the patient would not know which of the viruses was the one that brought on his cold.
The common cold differs in several ways from influenza or the flu. Cold symptoms develop gradually and are relatively mild. The flu has a sudden onset and has more serious symptoms the usually put the sufferer to bed, and the flu lasts about twice as long as the cold. Also influenza can be fatal, especially to elderly persons, though the number of influenza viruses is more limited than the number of cold viruses, and vaccines are available against certain types of flu.
Rhinoviruses, adenoviruses, influenza viruses, parainfluenza viruses, syncytial viruses, echoviruses, and coxsackie virusesll have been implicated as the agents that cause the
Passing the cold-causing virus from one person to the next can be done by sneezing onto the person, by shaking hands, or by an object handled by the infected person and picked up by the next victim. Oddly, direct contact with the infected person, as in kissing, is not an efficient way for the virus to spread. Only in about 10% of such contacts does the uninfected person get the virus. Walking around in a cold rain will not cause a cold. Viruses like warm, moist surroundings, so they thrive indoors in winter. Colds are easily passed in the winter, because people spend more time indoors then than they do outdoors. However, being outdoors in cold weather can dehydrate the mucous membranes in the nose and make them more susceptible to infection by a rhinovirus.
In addition, cold-causing viruses mutate with regularity. Each time it is passed from one person to the next, the virus changes slightly, so it is not the virus the first person had. Viruses are obligate parasites, meaning that they can carry out their functions only when they invade another living cell.
The virus has a tough envelope surrounding its nucleic acids, the genetic material for any living thing. Once it invades the body, the virus waits to be placed in the location in which it can function best. Once there, it attaches to a cell by means of receptor areas on its envelope and on the cell membrane. The viral nucleic acid then is inserted into the cell nucleus and it takes over the functions of the nucleus, telling it to reproduce viruses.
Taking regular doses of vitamin C will not ward off a cold. However, high doses of vitamin C once a person has a cold may help to alleviate symptoms and reduce discomfort. Over-the-counter drugs to treat colds treat only the symptoms. They may dry up the patient's runny nose, but after a few days the nose will compensate and overcome the effects of the medication and begin to drip again. The runny nose is from the loss of plasma from the blood vessels in the nose. Some researchers assert the nose drip is a defensive mechanism to prevent the invasion of other viruses. Antibiotics such as penicillin are useless against the cold because they do not affect viruses.
Scientists agree that the old wives' remedy of chicken soup can help the cold victim, but so can any other hot liquid. The steam and heat produced by soup or tea helps to liquefy the mucus in the sinus cavities, allowing them to drain, reducing the pressure and making the patient feel better. The remedy is temporary and has no effect on the virus. Colds are usually self-limiting, and recovery usually occurs within a week.
See also Cold, viruses; Infection and resistance; Viruses and responses to viral infection
Cold, Viruses (World of Microbiology and Immunology)
The cold is one of the most common illnesses of humans. In the Unites States alone, there are more than one billion colds each year. Typically a cold produces sneezing, scratchy throat, and a runny nose for one or two weeks. The causes of the common cold are viruses.
More than 200 different viruses can cause a cold. Rhinoviruses account for anywhere from 35% to over half of all colds, particularly in younger and older people. This has likely been the case for millennia. Indeed, the name Rhinovirus is from the Greek word rhin, meaning, "nose." There are over one hundred different types of Rhinovirus, based on the different proteins that are on the surface of the virus particle. Rhinovirus belongs to the virus family Picornaviridae. The genetic material of the virus is ribonucleic acid (RNA) and the genome is of a very small size.
Rhinovirus is spread from one person to another by "hand to hand" contact, that is, by physical contact or from one person sneezing close by another person. The virus needs to inside the human body to be able to replicate. The internal temperature of the body, which is normally between 979°F (36.17.2° C) is perfect for Rhinovirus. If the temperature varies only a few degrees either way of the window, the virus will not replicate.
Rhinovirus has been successful in causing colds for such as long time because of the large number of antigenic types of the virus that exist. Producing a vaccine against the virus would require the inclusion of hundreds of antibodies to the hundreds of different possible antigens. This is not practical to achieve. Furthermore, not all the Rhinovirus antigens that are important in generating a cold are exposed at the surface. So, even if a corresponding antibody were present, neutralization of the antigen via the binding of the antibody with the antigen would not occur. Another factor against vaccine development is the difficulty in being able to grow Rhinovirus in the laboratory.
Another virus that causes colds are members of the Coronavirus family. The name of the virus derives from the distinctive flexible shape and appearance of the virus particle. Surface projections give the virus a crown-like, or corona, appearance. There are more than 30 known strains of Coronavirus. Of these, three or four from the genus Coronavirus can infect humans. Cattle, pigs, rodents, cats, dogs, and birds are also hosts. Members of the genus Torovirus can also cause gastroenteritis.
Coronavirus has been known since 1937, when it was isolated from chickens. It was suspected of being a cause of colds, but this could not be proven until the 1960s, when techniques to grow the virus in laboratory cultures were devised. Like Rhinovirus, Coronavirus also contains RNA. However, in contrast to the same amount of genetic material carried in Rhinoviruses, the genome of the Coronavirus is the largest of all the RNA-containing viruses.
Other viruses account for 105% of colds in adults. These adenoviruses, coxsackieviruses, echoviruses, orthomyxoviruses (including the influenza A and B viruses), paramyxoviruses, respiratory syncytial virus and enteroviruses can also cause other, more severe illnesses.
Aside from vaccines, various "home remedies" to the common cold exist. Larger than normal doses of Vitamin C have been claimed to lessen the symptoms or prevent the common cold. The evidence for this claim is still not definitive. Another remedy, mythologized as an example of a mother's care for her children, is chicken soup. Studies have demonstrated that chicken soup may indeed shorten the length of a cold and relieve some of the symptoms. The active ingredient(s), if any, that are responsible are not known, however. For now, the best treatment for a cold is to attempt to relieve the symptoms via such home remedies and over the counter medications. Nasal decongestants decrease the secretions from the nose and help relieve congestion. Antihistamines act to depress the histamine allergic response of the immune system. This has been claimed to help relieve cold symptoms. Analgesics relieve some of pain and fever associated with a cold.
Some so-called alternative medications may have some benefit. For example, lozenges composed of zinc can sometimes reduce the duration of the common cold, perhaps due to the need for zinc by the immune system. Echinacea is known to stimulate white blood cell activity.
See also Virology