The common cold is probably the most common illness in the world. It is characterized by sneezing, a scratchy throat, a stuffy nose, and coughing. In the course of a year, people in the United States suffer 1 billion colds.
A cold is typically acquired by touching one's eyes or nose after touching surfaces with cold germs on them, or by inhaling the viruses. Symptoms usually begin 2 or 3 days after infection and last 2 to 14 days. Colds can be avoided by frequent hand-washing and by staying away from infected individuals.
There is currently no cure for the common cold. This is because the illness is caused by a virus which continuously mutates, constantly changes its genetic base sequence, making it hard to find a cure for all the variations of the common cold.
However, the best way to avoid this illness is to maintain a healthy immune system while practicing good hygiene. Many people find that using dietary supplements of Vitamins A, C, and D, as well as Zinc and other minerals and herbs can keep them healthy and/or enable them to recover from a cold much more quickly. For those less knowledgeable in supplementation, products such as Zicam® are often useful, as they contain some of these beneficial substances.
Is it caused by cold weather?
Cold weather has long been associated with the viral infection, and not entirely without reason. One cause of this apparent relationship is that people spend more time indoors during the cold winter weather. Spending extended time in close proximity to other people is a clear culprit. For this same reason, children in daycare or kindergarten are particularly prone to having colds. However, at least one study has found that cold weather does actually encourage the illness. Colder temperatures enable the virus to reproduce more quickly, and the host's immune response is slowed at the same time.
Another consideration is that cold weather is the result of the earth angling away from the sun. This reduces both the intensity and duration of exposure to the sun, which effects not only the weather, but the human body itself. When exposed to sunlight for a sufficient amount of time at a sufficient intensity, human skin begins converting cholesterol into Vitamin D. Therefore, during the summer, people in temperate zones tend to have higher Vitamin D levels. In the winter, however, sunbathing and other sunlight activities come to a halt, and outdoor activities are performed under heavy clothing. This combined with the already weakened rays prevents most of the skin's Vitamin D production. As Vitamin D levels drop during the autumn and winter, the immune system is weakened, and becomes less capable to fight off viral infection (as well probably at greater risk of other ailments). While people with fairly strong immune systems can still catch a cold, they are less likely to.
The illness begins with one or more virus, which contains DNA or RNA. The virus enters the soon-to-be host, and moves through the body. Some white blood cells will detect the virus as foreign and destroy it, if they come in contact with it. However, if the virus manages to escape these "sentries," it will eventually come to the kind of cell it seeks, and attach. The virus then injects the viral DNA or RNA, and detaches, now simply an inert shell (capsid). The attacked cell is then tricked by the viral genetic code, and begins creating viruses. The cell will often detect the problem, but be unable to stop the process—all it can do is warn others of its problem. The virus creation process continues until the cell becomes full of viruses, causing it to burst. This distributes new viruses, which will then attack other cells and potentially other people.
Having become quickly aware of the problem, the host body begins producing more white blood cells. However, it cannot yet properly target the infection, so it must largely rely on detecting the viruses as foreign objects. Eventually the host body is able to identify the exact contagion, and release antigens (antibodies) to detect and mark the viruses. With most viruses now marked, the remaining white blood cells such as the cytotoxic "Killer T" cells (lymphocytes) are able to detect the antigens attached to the known viruses, and destroy them. At this point, a healthy immune system is able to overpower the infection, and irradiate it.
Once the infection is removed, the host body continues for some time to produce antigens for that strain of virus. If the person becomes reinfected, the immune system is able to quickly stop the virus, usually long before the host experiences and symptoms. This immunity protects the host from that strain, but not all other variants. When another strain enters the body, the process begins again, since it is not recognized by the existing antigens.