Cold and Flu » Common Cold

Influenza, commonly known as flu, is an infectious disease of birds and mammals caused by RNA viruses of the family Orthomyxoviridae (the influenza viruses). The name influenza comes from the Italian: influenza, meaning "influence", (Latin: influentia). In humans, common symptoms of the disease are fever, sore throat, muscle pains, severe headache, coughing, weakness and general discomfort.[1] In more serious cases, influenza causes pneumonia, which can be fatal, particularly in young children and the elderly. Although it is sometimes confused with the common cold, influenza is a much more severe disease and is caused by a different type of virus. Influenza can produce nausea and vomiting, especially in children,[1] but these symptoms are more characteristic of the unrelated gastroenteritis, which is sometimes called "stomach flu" or "24-hour flu."

Typically influenza is transmitted from infected mammals through the air by coughs or sneezes, creating aerosols containing the virus, and from infected birds through their droppings. Influenza can also be transmitted by saliva, nasal secretions, faeces and blood. Infections also occur through contact with these body fluids or with contaminated surfaces. Flu viruses can remain infectious for about one week at human body temperature, over 30 days at 0 °C (32 °F), and indefinitely at very low temperatures (such as lakes in northeast Siberia). Most influenza strains can be inactivated easily by disinfectants and detergents.

Symptoms

Symptoms of influenza can start quite suddenly one to two days after infection. Usually the first symptoms are chills or a chilly sensation but fever is also common early in the infection, with body temperatures as high as 39 °C (approximately 103 °F). Many people are so ill that they are confined to bed for several days, with aches and pains throughout their bodies, which are worst in their backs and legs.

Common symptoms of the flu such as fever, headaches, and fatigue come from the huge amounts of proinflammatory cytokines and chemokines (such as interferon or tumor necrosis factor) produced from influenza-infected cells.  In contrast to the rhinovirus that causes the common cold, influenza does cause tissue damage, so symptoms are not entirely due to the inflammatory response.[48] Symptoms of influenza may include:

·         Body aches, especially joints and throat

·         Coughing and sneezing

·         Extreme coldness and fever

·         Fatigue

·         Headache

·         Irritated watering eyes

·         Nasal congestion

·         Nausea and vomiting

·         Reddened eyes, skin (especially face), mouth, throat and nose

It can be difficult to distinguish between the common cold and influenza in the early stages of these infections, but usually the symptoms of the flu are more severe than their common-cold equivalents.

Prevention

Vaccination and infection control

Influenza vaccine is strongly recommended for high-risk groups, such as children and the elderly.

It is possible to get vaccinated and still get influenza. The vaccine is reformulated each season for a few specific flu strains, but cannot possibly include all the strains actively infecting people in the world for that season. It takes about six months for the manufacturers to formulate and produce the millions of doses required to deal with the seasonal epidemics; occasionally, a new or overlooked strain becomes prominent during that time and infects people although they have been vaccinated (as by the H3N2 Fujian flu in the 2003–2004 flu season). It is also possible to get infected just before vaccination and get sick with the very strain that the vaccine is supposed to prevent, as the vaccine takes about two weeks to become effective.

The 2006–2007 season is the first in which the CDC has recommended that children younger than 59 months receive the annual influenza vaccine. Vaccines can cause the immune system to react as if the body were actually being infected, and general infection symptoms (many cold and flu symptoms are just general infection symptoms) can appear, though these symptoms are usually not as severe or long-lasting as influenza. The most dangerous side-effect is a severe allergic reaction to either the virus material itself, or residues from the hen eggs used to grow the influenza; however, these reactions are extremely rare.

Good personal health and hygiene habits are reasonably effective in avoiding and minimizing influenza. People who contract influenza are most infective between the second and third days after infection and infectivity lasts for around 10 days. Children are notably more infectious than adults, and shed virus from just before they develop symptoms until 2 weeks after infection.

Since influenza spreads through aerosols and contact with contaminated surfaces, it is important to persuade people to cover their mouths while sneezing and to wash their hands regularly. Surface sanitizing is recommended in areas where influenza may be present on surfaces.  Alcohol is an effective sanitizer against influenza viruses, while quaternary ammonium compounds can be used with alcohol, to increase the duration of the sanitizing action.[82] In hospitals, quaternary ammonium compounds and halogen-releasing agents such as sodium hypochlorite are commonly used to sanitize rooms or equipment that have been occupied by patients with influenza symptoms. During past pandemics, closing schools, churches and theaters slowed the spread of the virus but did not have a large effect on the overall death rate.

Treatment

People with the flu are advised to get plenty of rest, drink a lot of liquids, avoid using alcohol and tobacco and, if necessary, take medications such as paracetamol (acetaminophen) to relieve the fever and muscle aches associated with the flu. Children and teenagers with flu symptoms (particularly fever) should avoid taking aspirin during an influenza infection (especially influenza type B) because doing so can lead to Reye's syndrome, a rare but potentially fatal disease of the liver.[85] Since influenza is caused by a virus, antibiotics have no effect on the infection; unless prescribed for secondary infections such as bacterial pneumonia, they may lead to resistant bacteria. Antiviral medication is sometimes effective, but viruses can develop resistance to the standard antiviral drugs.