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The most widespread viruses that cause human disease are in the group of the Influenza A viruses. Most of the common seasonal flu viruses, the bird flu H5N1 virus, and the H1N1 swine flu virus that has emerged early this year, belong to this group

What is the flu?

Influenza which is more commonly called the flu, is a viral infection. The flu virus which causes the disease belongs to the family of Orthomyxaeviridae. Unlike plants and animals who use DNA, these viruses use RNA as their genetic material. RNA is less stable than DNA which allows the virus to mutate and change its molecular makeup very fast. Viruses from this family can infect birds and mammals. The most widespread viruses that cause human disease are in the group of the Influenza A viruses. Most of the common seasonal flu viruses, the bird flu H5N1 virus, and the H1N1 swine flu virus that has emerged early this year, belong to this group.

What are the symptoms of an infection with the flu?

The symptoms of an infection with an influenza virus usually start within one or two days of infection, and the feeling of being ill can begin rather abruptly. The first signs are usually a chill, and a fever of at least 100oF. The fever can become quite high and is one of the signs that differentiate an infection with the flu virus from the common cold. Other symptoms are headaches, muscle aches, joint aches, a general feeling of being ill (malaise), runny or stuffy nose, coughing, and sore throat. An infection with the flu virus can also cause nausea and vomiting, but that is less common. The disease is usually mild to moderate, but it can be severe and even cause death in some people, especially in high risk groups (small children and the elderly, and people with underlying health conditions).

How is the flu spread?

People with the flu are usually contagious up to 24 h before the first symptoms appear and for at least 24h after the fever has subsided. Since children have usually not as well developed immune responses to the virus as adults who have been infected with flu viruses many times before, children shed more virus than adults and are therefore more contagious. Viruses are shed by coughing and sneezing in the form of little droplets that can stay in the air and form an aerosol. Inhaling droplets of this virus-containing aerosol can lead to an infection. How long the viruses can survive in the air depends on the humidity of the air and the amount of UV radiation with both factors being favorable for the survival of the flu virus in winter (relatively low humidity and sunlight). Flu viruses can also survive outside of the body on surfaces like door knobs and light switches, or even banknotes and coins. From there they can get transported via hand-nose, hand-eye or hand-mouth contact to mucus membranes that can be infected directly.

10 easy steps to avoid cold and flu

1.    Vaccination

The flu vaccine is the best way to avoid infection. The vaccine can come in two forms: an injectable form aka “the flu” shot which is injected via needle and syringe into the arm and contains inactivated (killed) virus. Everyone older than 6 months including people with other illnesses can get this vaccine. The nasal spray vaccine which contains a weakened live flu virus should be only used by healthy people between the age of 2 and 49 years. It is not for women who are pregnant.

These two forms of the vaccine are now available for the regular seasonal flu as well as for the 2009 H1N1 swine flu pandemic. These two vaccinations are protecting against different viruses and one does not protect against the flu cause by the other, so that everyone who wants to have full protection by the vaccination will need to get both, the regular seasonal flu vaccine and the vaccine against the H1N1 swine flu. Since the flu virus can change its molecular makeup very fast, the vaccination has to be repeated every year.

2.    Wash hands

Washing hands often with soap and water or when unavailable rubbing them with an alcohol-based hand disinfectant will help with the spreading of many diseases among which is the flu. Since flu viruses can survive outside the body on surfaces like door knobs and banknotes, touching these items after they have been touched by a sick person who might have sneezed into their hand just prior, can deposit the germs on your hands. From the hands they are easily introduced to the mucus membranes in the mouth, nose and eyes, where the infection occurs.

3.    Sneeze into elbow

To avoid spraying highly contagious aerosol droplets that contain enough virus to infect a person by inhaling a single droplet, when sneezing or coughing, cover your sneeze and cough. Covering the sneeze and cough with the hand, will deposit the contagious material on them and after touching a doorknob, the disease will spread. Sneeze or cough into you elbow, where nobody is likely to touch and contract the disease.

4.    Keep hands and fingers away from mouth, eyes and nose

Hands might easily come into contact with live virus on door knobs, light switches, bank notes and other items that are touched by many people. Activities like rubbing the nose and eyes, and biting fingernails can easily transfer these germs into the mouth, nose and eyes where they can infect the mucous membranes.

5.    Stay at home when sick

To avoid spreading the flu within your community and putting other people at risk, stay at home when you’re sick and don’t return to work at least for 24h after your fever has disappeared.

6.    Avoid close contact with sick people

This seems to be the easiest of all ways to avoid getting sick, but in reality it might be the hardest. When your sick co-worker comes to work, try to convince him or her to go home. If you care for your sick child be particularly diligent about hand washing and not touching yourself in the face. Some things require a little imagination e.g. you can invent a new good night ritual for the sick child that’s very special to avoid the good-night kiss, and not make the child feel bad.

7.    Avoid crowds

People infected with the flu virus are contagious before they develop the first symptoms. So even if everybody stays home when they are sick which is probably a very optimistic assumption, where many people gather, the chances to come into contact with somebody who is contagious are very high. If authorities give advice about school closures, and other social distancing measures (e.g. avoiding of movie theaters), follow this advice.

8.    Sanitize surfaces

The flu virus can live on a hard surface for 1-2 days. To minimizes the chances to contract the flu from touching a door knob light switch, the telephone or other surfaces, sanitize these items and hard surfaces in your household and workplace on a regular basis.

9.    Practice good health habits

If you are in top health, your chances to fight of an infection without getting sick are the best. So make sure you get enough sleep, eating nutritious food to get your daily recommended allowance of vitamins, and exercises regularly. To quit smoking might be one of the best ways to prevent the flu, as numerous studies have shown that smokers contract the flu much more easily and have a higher chance of getting flu-related complications than non-smokers.

10.    Masks/airflow in home

To reduce the chance of contracting the flu via airborne aerosol droplets, it can be useful to wear a facemask when caring for a sick person. Open the windows regularly to allow fresh air into the house. Whether the wearing of face masks in public can help reduce your chances of getting the flu is controversial.

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