Common Cold Pathology The common cold is caused by numerous viruses (mainly rhinoviruses, coronaviruses and also certain echoviruses and coxsackieviruses) infecting the upper respiratory system. Several hundred cold causing viruses have been described, and a virus can mutate to survive, ensuring that any cure is still a long way off if not impossible. These are transmitted from person to person by droplets resulting from coughs or sneezes. The droplets are either inhaled directly, or, more commonly, transmitted from hand to hand via handshakes or objects such as door knobs, and then introduced to the nasal passages when the hand touches the nose, mouth or eyes. The virus enters the cells of the lining of the nose and throat, and rapidly multiplies inside them. Seventy-five percent of people exposed to a cold virus become infected with symptoms. The symptoms start 1-2 days after infection. They are a result of the body's defense mechanisms: sneezes, runny nose and coughs to expel the invader, and inflammation to attract and activate immune cells. The virus takes advantage of sneezes and coughs to infect the next person before it is killed by the body's immune system. A sufferer is most infectious within the first three days of the illness. After a common cold, a sufferer develops immunity to the particular virus encountered. Because of the large number of different cold viruses however, this immunity is of limited use and a person can easily be infected by another cold virus to start the process all over again. The term "cold" is misleading, if "cold" refers to climatic temperature, as the temperature does not appear to play a role, nor are any other factors known which affect the probability of infection. A person can best avoid colds by avoiding those who are ill and objects they touch, as well as keeping their immune system in top form by getting enough sleep, eating nutritious foods, and avoiding alcohol consumption. It is perhaps the case that "cold" refers to a "cold condition," i.e., the hot, cold, dry and wet "conditions" described by the ancient Roman physician Galen. Colds are somewhat more common in winter since during that time of the year people spend more time indoor in close proximity of others and ventilation is less, increasing the infection risk. Weak health or other allergies can be aggravated due to infection. Complications Bacteria that are normally present in the respiratory tract can take advantage of the weakened immune system during a common cold and produce a co-infection. Bacterial sinusitis is a common coinfection. A possible explanation for these coinfections is that strong blowing of the nose drives nasal fluids into those areas. Prevention The best way to avoid a cold is to avoid close contact with existing sufferers, to wash hands regularly(anti-bacterial soaps have no effect), and to avoid touching the face. In some countries, such as Japan, people with the common cold wear surgical masks. Because of the large variety of viruses causing the common cold, vaccination is impractical. Treatment There is no cure for the common cold, i.e. there is no treatment that directly fights the virus. Only the body's immune system can effectively destroy the invader. A cold may be composed of several million viral particles, and typically within a few days the body begins mass producing a better tailored antibody that can prevent the virus from infecting cells, as well as white blood cells which destroy the virus and destroy infected cells to prevent further viral replication. Available treatments therefore focus on relieving the symptoms. For some people, even without these remedies, 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, and the possibility, not yet scientifically proven, that by suppressing responses evolved to fight the cold, the symptom supressants may prolong the illness. Common treatments include: analgesics such as NSAIDs such as aspirin or acetaminophen as well as localised versions targeting the throat (often delivered in lozenge form), nasal decongestants which reduce the inflammation in the nasal passages by constricting local blood vessels, cough suppressants (which work like a narcotic to suppress the cough reflex of the brain or by diluting the mucus in the lungs), and first generation anti-histamines such as brompheniramine, chlorpheniramine, 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. A warm and humid environment and drinking lots of hot fluids alleviate symptoms somewhat. Common home remedies include camomile tea, chicken soup, medicinal mixtures, hot compresses, hot toddies, vitamin C, although despite several scientific trials there is no evidence that the final two have a beneficial effect. Hot beer is also recommended, and though it does little to fight the infection directly, at least it can help to a good night of relaxed sleep. Zinc-nasal sprays claim clinical proof that they work. The trick seems to be threefold. 1-The treatment has to be a nasal spray. 2-Treatment should be started at the first sign of a cold before it has the chance to get established. 3-The type of zinc must be zinc gluconate usually labelled as zincum gluconicum. Antibiotics are ineffective against the common cold and all other viral infections. They are useful in treating any secondary bacterial infections that sometimes occur, but treatment with antibiotics before these coinfections develop is counterproductive, as it produces drug resistance, and can even promote infections by killing off normal bodily flora. History Colds were known in ancient Egypt; there were hieroglyphs for cough and for the common cold. The Greek Hippocrates gave a description of the disease in the 5th century BC. In the 18th century, John Wesley wrote a book about curing diseases; it advised cold baths as prevention and stated 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 of microscopic infectious agents causing disease 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 with 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, 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 Alphonse Dochez repeated them in the 1920s, first in chimpanzees, and then in human volunteers using a proper double-blind setup. Among laymen, the common assumption that cold or wet clothes or feet cause the common cold persists to this day. In Britain, the civilian Medical Research Council set up the Common Cold Unit in 1946. The unit worked with volunteers who were infected with various viruses. The rhinoviruses were discovered there. In the late 1950s, it was shown how to grow these cold viruses in tissue culture. In the 1970s, it was also shown 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. Beginning in the 1960s, Nobel Prize winner Linus Pauling heavily advocated the intake of large doses of Vitamin C to prevent infection. In 1970 he wrote the bestseller Vitamin C and the Common Cold. However, several subsequent studies have shown that the vitamin does not have a protective effect against the common cold.