Swine Flu (H1N1) - Information for laymen

Learn everything about swine flu (influenza A) and discover why there is no reason to panic. Share this link to avoid unnecessary panic among the population.

The swine flu, or flu, is caused by influenza A (H1N1), the same as everyone else already had.

Swine flu
Swine flu

So why so much repercussion now?

Swine Flu (H1N1)
Influenza A is a virus that infects not only humans but also other mammals and birds. There are several subtypes - such as A (H1N1) - and between subtypes, several different strains. Swine flu is caused by a new strain of subtype A (H1N1) Influenza virus.

The great problem of the influenza virus is its great capacity to mutate, circulating a new strain almost every year, causing new epidemics of flu.

We have frequent contact with various subtypes and several different strains of influenza, which means that we always have some degree of immunity against the viruses circulating among humans. Epidemics usually occur when severe strains came from poultry or other animals cross the species barrier and infect humans. Normally we do not have these antibodies and are more susceptible to infections.

The same Influenza A (H1N1) was responsible for the famous Spanish flu in the early twentieth century, a pandemic that caused the death of more than 50 million people around the world. The origin of the epidemic seems to have been strains originating from swine flu.

Earlier this decade there was an epidemic of the bird flu, which was caused by another subtype of Influenza A, H5N1. Before you panic and run out to buy masks and stock of drugs, it is worth explaining here.

The flu always caused deaths and hospitalizations. Just to illustrate, in the United States each year more than 200,000 people are hospitalized due to flu, and between 1972 and 1992 more than 400,000 deaths were attributed to complications of influenza. On average, there are 20,000 flu deaths annually in the U.S. alone. As you can see, death from flu is nothing unusual.

Risk group:

Risk group of H1N1
Risk group of H1N1
  • Under 5 years old
  • Over 65 years old
  • Persons under 19 with chronic use of aspirin
  • Pregnancy
  • Individuals with lung diseases, including asthma, bronchitis and emphysema
  • Individuals with cardiovascular disease (except those with hypertension alone)
  • Renal
  • Liver failure / cirrhosis
  • Diabetes
  • Sickle cell anemia
  • Immunosuppressed, including HIV with CD4 counts less than 200 c / microL
  • Malnutrition
  • Morbid obesity

Warning, this is considered a risk group for both swine flu and for regular flu. As far as swine flu is concerned, this group is not more serious than the flu or other influenza viruses.

This strain of influenza A virus was restricted to pigs, and for some genetic mutation, acquired the ability to be transmitted from pigs to men and men to men. Swine flu is known in veterinary medicine since 1930. There is even a vaccine for pigs.

Due to the fact that the virus can now cross species, our immune system is unprepared as the seasonal flu virus is different from swine flu. But what seemed a serious epidemic in theory, in practice has proved to be much less dangerous than previously thought. Current data show that there are no signs of the virus to be more dangerous than the common flu. Rather, it appears to be milder.

A curiosity in the current epidemic is the lowest rate of impairment among the elderly, probably because the current virus is similar to strains that circulated before the decade of 50-60, thus providing some degree of immunity to this group.

The mortality has been low as in any influenza, especially for those who are not in the risk group described above. In the U.S. mortality is below 0.5% so far. In Mexico, which is the epicenter of the epidemic and the country with the worst health conditions, mortality is less than 1%.

Due to the large number of little symptomatic H1N1 infections, the mortality criterion mentioned above is no longer reliable. Many cases are not being counted simply because people do not seek medical attention. This underestimates the number of actual cases and overestimates the rate of mortality, since only the most serious cases are being reported.

Another important fact: the number of attendances with suspected cases of flu (swine or seasonal) from January to July is similar to what occurs in the same period since 2003. What seems to be happening is just an exchange of seasonal influenza by H1N1 influenza, without influence on the total number of cases, mortality or complication rates.

Of the 10,623 cases of suspected some kind of flu, 1,958 (18.4%) were confirmed as influenza A (H1N1) and 669 (6.3%) as seasonal influenza. Therefore, less than 25% of people seeking medical care with suspected flu, actually have this diagnosis.

The rate of complications from influenza H1N1 remains similar to seasonal influenza (19% versus 18.5% of confirmed cases). We should bear in mind that only symptomatic cases have been reported. These values of 19% and 18.5% of complications do not refer to all cases of influenza A, but only those who are more symptomatic in which doctors ask to confirm the diagnosis.

The mortality rate from H1N1 among those who develop complications such as severe acute respiratory syndrome (SARS) fell from 12.8% to 10.3% since the last newsletter of the Ministry of Health.

Among cases of SARS caused by the H1N1 mortality rate is 15.1% for patients with at least one risk factor and 4.36% for those who do not present a risk factor.

Chronic respiratory diseases and pregnancy are the main risk factors for the development of SARS in both the H1N1 and seasonal flu.

In the specific case of pregnant women, 7.2% of those who had confirmed H1N1 had complications, compared with 7.9% of those with seasonal flu. Therefore, in Brazil, the common flu still causes statistically more complications during pregnancy than influenza A. Again remember that the figures refer to cases with not all pregnant women with flu.

Transmission of swine flu

Swine flu transmission
Swine flu transmission
Swine flu is transmitted like any other flu, through respiratory secretions. At first it was passed through a pig, but the outbreak occurs by human to human transmission. There is no risk of contamination through pig meat. The virus does not survive during the cooking process.

Since the outbreak is still very young, it is not clear about the incubation period, or for how long the infected person transmits the virus. It is believed that the data are similar to the other influenza caused by other strains of the A (H1N1), with transmission of the day before going to the onset of symptoms within 24 hours after termination of foot, and an incubation period of 1-7 days.

Therefore, the WHO recommends for those with flu symptoms to be quarantined until 24 hours after resolution of symptoms (fever) to avoid infecting other people.

The use of masks was widespread among the population and it was possible to see some people walking down the street wearing one. There are no indications that common masks effectively protect against H1N1 infection.

How to avoid H1N1
How to avoid H1N1
The masks lose their protective capability after some moisture due to respiration and perspiration appears on it. Its use should be restricted to health professionals in contact with patients and people in risk group patients who have relatives in the same household. Infected persons should use it, if they can tolerate it.

The virus can stay alive on inanimate objects for up to 8 hours. A simple cleaning with soap or detergent is enough to kill it. Pools do not transmit the virus due to the presence of chlorine.

As preventions can serve:
  • Avoid close contact with people (at least 2 meters).
  • Avoid bare-hand contact with eyes and mouth without first washing them.
  • Wash your hands frequently.
  • Avoid being in low air circulation and with many people.

Symptoms of swine flu

The clinical picture of swine flu is very similar to flu, with fever, headache, cough, sore throat, muscle aches. The only difference is that it can also occur with diarrhea and vomiting, which is uncommon in simple flu.

In young children and the elderly people there is high risk for complications, symptoms may be less typical, occurring only fever and lethargy. Fever is the most important symptom for diagnosis.

If there is a temperature higher than 37.5°C, the diagnosis of swine flu becomes less likely. The complications of swine flu are the same as of seasonal flu. The main one is pneumonia and SARS, which is usually the cause of death in those who develop it.

Unlike colds, the flu is an infection that develops very fast. Within 24-48 hours the patient has any clinical features. People who return travel from countries with high levels of contamination should be aware of the symptoms for at least 10 days after return. No need to quarantine if there are no symptoms, even for those who have ill family members at home.

Symptoms of swine flu
Symptoms of swine flu

What are the danger signals?

  • Difficulty breathing
  • Chest pain while breathing
  • Low pressure
  • Changes in consciousness
  • Disorientation
  • Persistent vomiting

It is important to realize that when we talk about risk group we refer to those with higher risk of developing complications from influenza (seasonal or swine). This does not in any way mean that these people must have complications, or those who do not belong to the group are in no danger. We're talking about probabilities, not certainties.


Again it is important to note that in most people the swine flu has a mild, like any flu, spontaneous resolution.

The antiviral treatment decreases the incidence of complications and shortens the time of disease promoting breakage of the transmission chain. The main drug that has been used is oseltamivir (Tamiflu). The medicine works best if taken within the first 48 hours after first symptoms.


There are no studies proving the safety of oseltamivir (Tamiflu) for pregnant women. However, due to higher number of complications in this group, the U.S. CDC (Centers for Disease Control and Prevention) authorizes the use of Tamiflu by pregnant women.

Oseltamivir (Tamiflu) for some years is used in cases of common colds. You do not need to have confirmation of H1N1 to start the drug but just the presence of symptoms of flu (swine or is not). However, the antiviral is only indicated for patients with severe signs or which belong to the risk group. People outside the group risk and with mild symptoms are not at risk of death and therefore do not need the drug.

The trivialization of the use of oseltamivir (Tamiflu) can lead to an increased resistance of H1N1. Join the fact of common drugs have side effects, and one can understand why it should not be prescribed indiscriminately.

Those who take the flu vaccine might provide at least a partial immunization, since the H1N1 strain is similar to human flu. Anyone who has caught swine flu and recovered is immune.

The important thing is not to create panic among the population. So far there is no evidence that swine flu is more serious than the common flu that we all have. All eyes are focused on trying to prevent the virus circulating among the population. First, because the more people are infected and transmit the virus, the greater is the number of deaths. Second, because the more the virus circulates, the more difficult it is for seniors and people with weak immune system to avoid contamination.

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