Influenza A virus

Alternative Names: swine flu; influenzavirus A; pig flu, influenza A

What is it?

It is a disease caused by a mutation (usually H1N1) from influenza virus A. Therefore, it is a new virus, with genetic material unknown to the immune system of people. This new virus has emerged due to a large antigenic variation of influenza virus.

This phenomenon occurs at irregular intervals ranging from 10 to 40 years.  It is an acute respiratory disease, highly contagious, affecting the whole world quickly in 2009 because people did not have immunity against it.  The Worl Health Organization (WHO) sounded the alarm on the pandemic (epidemiological alert level 6) on June 2009 due to the gravity of the situation.

So far, 17 thousand Americans, including 1800 children, were reported dead . The Centers for Disease Control and Prevention (CDC) estimate that 41 to 84 million cases of H1N1 have occurred between April 2009 and January 2010. With pigs, in turn, the disease is considered endemic in the United States, and outbreaks occurred in North and South America, Europe, Africa and parts of east Asia.

 How does it occur?

The virus is spread among pigs through aerosols of respiratory secretions by direct or indirect contact. They can be infected by influenza viruses from birds, humans as well as swine influenza. Pigs can be infected simultaneously by more than one type of virus, allowing them to mingle. The human infection with swine influenza can occur in isolated cases or outbreaks. This disease can occur after contact of a healthy person  and an infected pig  or healthy person with an infected person.  However, currently there is no confirmation of transmission between pigs and humans.

 Thus, as in common colds, the contagion between people occurs through respiratory secretions like saliva droplets when speaking, sneezing or coughing. A person can infect another since the day before the disease appears to 7 days (children even more than that) after its resolution. After contact with the virus, the individual may take 1-4 days to start showing the signs and symptoms of disease.

 How does it feel?

The symptoms are similar to flu symptoms. The affected individual may have abrupt onset of high fever associated with cough, muscle aches and joint pain, headache, prostration, coryza, sore throat, chills and sometimes vomiting and diarrhea. The disease may progress to shortness of breath and respiratory failure followed by death. Contudo, a grande maioria dos casos evolui espontaneamente para cura sem apresentar complicações. However, the vast majority of cases result in spontaneous healing without adverse effects.

How do you avoid it?

 These cases of flu can occur at any time of the year.  However, it has a higher incidence in autumn-winter in the temperate zones of the globe. Many countries routinely vaccinate swine populations against this virus.

For humans, this year, there is already a vaccine approved for use and the Ministry of Health has set a complete schedule for vaccination against this disease and it is estimated that 91 million people will be vaccinated  in Brazil.  It will be free and will be divided into five stages according to the target audience.  See table below:

 
TABLE OF VACCINATION AGAINST INFLUENZAVIRUS A (H1N1) 2010 OF THE MINISTRY OF HEALTH
 
8 to 19 March Health Professionals Doctors, nurses, receptionists, cleaning staff and security, ambulance drivers, teams and laboratory professionals engaged in epidemiological research.
8 to 19 March Indigenous Peoples Population living in villages. Vaccination will be carried out in partnership with Funasa (National Health Foundation).
March 22 to April 2 Pregnant women Pregnant women in any period of gestation. Women who become pregnant after April 2 may have the vaccine until May 21.
March 22 to April 2  People with chronic conditions up to 60 years old  People will be vaccinated with the following conditions:
• Obesity lelvel 3 – formerly designated extreme obesity (children, adolescents and adults);
• chronic respiratory diseases since childhood (examples: cystic fibrosis, bronchopulmonary dysplasia);
• Asthmatics (severe types);
• Chronic obstructive pulmonary disease and other chronic respiratory failures;
•  Neuromuscular disease with impairment of respiratory function (eg, neuromuscular dystrophy);
• immunosuppressed (eg patients undergoing treatment for cancer or AIDS and people with diseases that weaken the immune system);
• Diabetes mellitus;
• Doença hepática (exemplos: atresia biliar, cirrose, hepatite crônica com alteração da função hepática e/ou terapêutica antiviral); • Liver disease (eg biliary atresia, cirrhosis, chronic hepatitis with abnormal liver function and/or antiviral therapy);
• Renal disease (eg chronic renal failure, especially in dialysis patients);
• hematologic Disease (hemoglobinpathy);
• Patients under 18  with continuous therapy with salicylates (eg autoimmune rheumatic disease, Kawasaki disease);
• Patients with Clinical Syndrome of Heart Failure;
•  Patients with structural heart disease with clinical and/ or hemodynamic repercussion (eg pulmonary arterial hypertension, valvular heart disease, ischemic heart disease with ventricular dysfunction).
 March 22 to April 2  Children between six months and two years old incomplete (23 months).  They should receive the   half a dosis and, after 21 days,  another half dosis.
 5 to 23 April  Population 20 to 29 years  Anyone in this age group.
 April 24 to May 7  Elderly people with chronic problems (over 60 years ).  The period coincides with the vaccination of the elderly for the flu.  While taking the vaccine, they will also receive immunization against influenzavirus A (H1N1) if they have any of these problems:

• Obesity level 3 – formerly extreme obesity (children, adolescents and adults);
• chronic respiratory diseases since childhood (examples: cystic fibrosis, bronchopulmonary dysplasia);
 • Asthmatics (severe);
• Chronic obstructive pulmonary disease and other chronic respiratory failure;
•  Neuromuscular disease with impairment of respiratory function (eg, neuromuscular dystrophy);
• Imunodeprimidos (exemplos: pacientes em tratamento para aids e câncer ou portadores de doenças que debilitam o sistema imunológico); • immunosuppressed (eg patients undergoing treatment for cancer or AIDS and people with diseases that weaken the immune system);
• Diabetes mellitus;
•  Liver disease (eg biliary atresia, cirrhosis, chronic hepatitis with abnormal liver function and/or antiviral therapy);
•  Renal disease (eg chronic renal failure, especially in dialysis patients);
• Hematologic Disease (hemoglobinpathy);  
• Patients under 18 years in continuous therapy with salicylates (eg autoimmune rheumatic disease, Kawasaki disease);
 • Patients with Clinical Syndrome of Heart Failure;
• Patients with structural heart disease with clinical and/or hemodynamic repercussion (eg pulmonary hypertension, valvular heart disease, ischemic heart disease with ventricular dysfunction)

 10 to 21 May  Population 30 to 39 years

 Anyone in this age group.

 
The Ministry of Health has defined the aforementioned groups based on their vulnerability of developing the disease, and does not recommend for people outside said groups. Immunization begins March 8. People allergic to eggs should not be vaccinated as well as people who have developed Guillain-Barré syndrome after vaccination.

It is okay to eat pork or its products (salami, for example). The disease is not contracted this way.

For people who deal daily with pigs, it is recommended to practice good hygiene, always essential in any contact with animals, especially during and after slaughter and handling, to prevent exposure to the disease agents. Sick animals that have died from disease should not be processed in slaughterhouses, and the competent authorities must be informed about any relevant events.

 For personal protection some preventive measures should be used : 

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