What is it?

It is a respiratory infection caused by the Influenza virus. It can affect millions of people each year. It is highly contagious that usually occurs in the late Autumn, Winter and beginning of Spring. It is also responsible for much of the work and school absenteeism and, in addition, it can possibly to lead to pneumonia, hospitalization and death. There are three types of virus: A, B and C. The Influenza A virus can infect humans and other animals, while the Influenza B and C can only infect humans. The C type causes a very mild flu and no epidemics. Generally, the influenza virus occurs in epidemics once a year. Anyone can get the flu. However, individuals with chronic respiratory diseases, poor immunity and elderly people have a tendency to more severe infections with possibility of fatal complications.

The symptoms of the flu are frequently more severe than those of a cold. The Influenza virus has a ‘covering’ that constantly changes itself. This causes the individual’s organism to have difficulty defending itself from this microorganism’s attacks and, therefore, it becomes difficult to develop vaccines for protection against the infection it causes. Therefore, the flu is one of the major public health issues.

How does it develop?

Unlike cold that most of the time spreads through direct contact with people, Influenza virus spreads principally through the air. When a person with flu sneezes, coughs or speaks, tiny droplets with the virus disperse in the air for enough time to be inhaled by another person. The virus reproduces itself in the lining of the infected individual’s nose and then spreads to the throat and the rest of the airways, including the lungs, and causing the flu symptoms.

Less frequently, the disease may be transmitted through the touch of hand (of the infected individual) on the healthy individual’s hand who, taking the hand to the mouth or nose, becomes infected. On any given day, before the individual may feel the symptoms, he/she can already infect other ones up to 7 days after onset of symptoms – children even more than this.

How does one feel?

Influenza is different from a cold. Flu is a disease with a sudden onset and more severe than the common cold. Incubation period – time between of contagion and the onset of symptoms – is 1-2 days.


Excessive sweating
Unproductive cough – may last over two weeks
Muscular and articular pain (body pain) – may last 3-5 days
Fatigue – may take more than two weeks to disappears
perda de peso.
Sore throat
Congested nose

Either some or all of the symptoms above may be present. The disease usually remits within one or two weeks. The fever can last 3-8 days. In elderly people, the weakness caused by the flu can last for several weeks. A likely complication of the flu is pneumonia – normally, not through Influenza virus, but through a bacterium – pneumococcus or staphylococcus, in general.

In addition to pneumonia, other infections such as sinusitis, otitis and bronchitis (infection of the bronchi – ‘tubes’ conveying air to the lungs) are also likely complications. People over 65-years-old, and those any age with some chronic disease, and very small children are more likely to develop flu complications. On the other hand, the flu can also trigger a deterioration of the condition in those individuals with asthma and those with heart failure, for instance.

How does the doctor make the diagnosis?

The doctor makes the diagnosis based on the signs and the symptoms referred to by the patient and the aid of the physical examination. Nevertheless, this is not an easy task, since the early symptoms of the disease can be similar to those caused by other microorganisms in other diseases. Therefore, there are tests that can be performed – only applied in case of epidemics or as the doctor sees fit for the management of the condition – to confirm the disease. These tests can be made

with the analyses of the respiratory secretion (a scrape technique applied to the throat, with the aid a cotton-tipped swab, or nose secretion), on the first 4 days of the ailment, or through a blood test. There are also the so-called quick-check tests that can confirm the disease within 24 hours. If the doctor suspects any complications caused by the influenza virus, he can also have the patient have these complementary tests.

A thorax radiography will also help the doctor if pneumonia is suspected as complication of flu or other diagnosis. How is it treated?

If the symptoms have appeared less than two days ago, the patient can discuss with his doctor the possibility of having an anti-viral treatment. The ailing individual should rest, avoid the use of alcohol or smoking, follow a proper diet and drink a lot of fluids, in addition to using the medication for fever and pain – aspirin (for individuals over 18-years-old), acetaminophen or ibuprofen. Other medicines can be used for improving the running nose or nasal congestion.

Normal activities should only be resumed after the symptoms are over. To fight or prevent the flu by influenzavírus A, the amantadine can be used in children over one-year-old. Rimantadine is another option in these cases. However, only adults can be treated with it. These two antiviral medicines can help in the process of cure if used in the first 48 hours of the disease. Two new efficient antiviral drugs called neuraminidase inhibitors – the zanamivir and the oseltamivir – have an advantage of acting against both influenza A and influenza B.

How to prevent it?

Yearly vaccination before the start of the season winter, when it mostly occurs, is the best means of preventing influenza. It can help prevent the cases of flu or, at least, diminishes the severity of the disease. Its effectiveness among young adults is 70-90%. It falls to 30-40% in very weak elderly people – this is because they have little capacity to develop protecting antibodies after the immunization (vaccination). However, even in these cases the vaccination was able to protect against severe complications of the disease such as hospitalizations and deaths.


all people with 50 years-old or more. Adults or individuals over 6 months-old with chronic heart, lungs or kidney diseases Diabetics and people with hemoglobin disease (of the blood) People having the immune system compromised: with cancer, infected with, HIV, organ transplanted or having received corticoids, chemotherapy or radiotherapy . healthcare workers family members and those involved in the care of people with high risk of becoming ill.

Pregnant women at 24 or 36 weeks, during the period of the year in which the flu is most frequent, or those showing some medical condition that represents a higher risk of complication after a flu. Individuals between 6 months and 18-years-old making use of acetylsalicylic acid for a long time are likely to develop a severe complication called the Reye Syndrome from the flu).


People who have showed a previous reaction to this vaccine against the flu People who have already showed an allergic reaction to chicken eggs Individuals who have had a disorder characterized by paralysis called Guillain-Barré Syndrome, which is suspected to have developed after an anti-Influenza vaccination People with some current feverish condition.


How long should an individual with a flu stay away from his/her ordinary activities? Is the individual who had the vaccination against the flu likely to develop the condition in the same year? Can healthy adults under 60 years old benefit from the yearly vaccine? Which are the antiviral drugs available in the market and for how many days should they be used?