Cough, Cold, Flu

Acute viral nasopharyngitis, often known as the common cold, is a mild viral infectious disease of the upper respiratory system (nose and throat). more...

Home
Bath & Body
Dietary Supplements,...
Hair Care
Hair Removal
Health Care
Massage
Medical, Special Needs
Nail
Natural Therapies
Oral Care
Other Health & Beauty Items
Coupons
Over-the-Counter Medicine
Allergy, Sinus, Asthma
Cough, Cold, Flu
Digestion, Nausea
Other
Pain Relief
Tanning Beds, Lamps
Skin Care
Tattoos, Body Art
Vision Care
Weight Management
Wholesale Lots

Symptoms include sneezing, sniffling, runny nose, nasal congestion; scratchy, sore, or phlegmy throat; coughing; headache; and tiredness. Colds typically last three to five days, with residual coughing and/or catarrh lasting up to three weeks. It is the most common of all human diseases, infecting adults at an average rate of 2–4 infections per year, and school-aged children as many as 12 times per year. Infection rates greater than three infections per year per person are not uncommon in some populations. Children and their parents or caretakers are at a higher risk, possibly due to the high population density of schools and because transmission to family members is highly efficient.

The common cold belongs to the upper respiratory tract infections. It is different from influenza, a more severe viral infection of the respiratory tract that shows the additional symptoms of rapidly rising fever, chills, and body and muscle aches. While the common cold itself is rarely life-threatening, its complications, such as pneumonia, can be.

Pathology

The common cold is caused by numerous viruses (mainly rhinoviruses, coronaviruses, and also certain echoviruses, paramyxoviruses, and coxsackieviruses) infecting the upper inspiratory system. Several hundred cold-causing viruses have been described, and a virus can evolve to survive, ensuring that any cure is still a long way off. The nasopharynx is the central area infected. The reasons that the virus concentrates in the nasopharynx rather than the throat may be the low temperature and high concentration of cells with receptors needed for the virus.

Transmission

The viruses are transmitted from person to person in two ways. The most effective is by physical contact: a cold sufferer wipes his or her nose, shakes hands with someone who then rubs his or her eyes or nose. There is a lesser but significant level of infection from inhaling droplets from coughs or sneezes (Tyrrell DA, Ann. Rev Microbiology 1988 42 35-47). Infective cold viruses can also persist on objects that have been handled, such as doorknobs and shopping carts, with a half-life of about one hour.

The virus takes advantage of both the copious flow of nasal fluid and sneezes and coughs to infect the next person before it is defeated by the body's immune system. Sneezes expel a significantly larger concentration of virus "cloud" than coughing. The "cloud" is partly invisible and falls at a rate slow enough to last for hours—with part of the droplet nuclei evaporating and leaving much smaller and invisible "droplet nuclei" in the air. Droplets from turbulent sneezing or coughing or hand contact also can last for hours on surfaces, although less virus can be recovered from porous surfaces such as wood or paper towel than non-porous surfaces such as a metal bar. A sufferer is most infectious within the first three 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, likely controlling the virus at concentrations too low for them to have symptoms.

Read more at Wikipedia.org