What is swine flu ?

 Swine flu (swine influenza) is a disease of pigs. It is a highly contagious respiratory disease caused by one of many Influenza A viruses. Approximately 1% to 4% of pigs that get swine flu die from it. It is spread among pigs by direct and indirect contact, aerosols, and from pigs that are infected but do not have symptoms. In many parts of the world pigs are vaccinated against swine flu.

Most commonly, swine flu is of the H1N1 influenza subtype. However, they can sometimes come from the other types, such as H1N2, H3N1, and H3N2.

The current outbreak of swine flu that has infected humans is of the H1N1 type - this type is not as dangerous as some others.

Why it is called SWINE FLU ?

It is thought to be a mutation of four known strains of the influenza A virus, subtype H1N1: one endemic in (normally infecting) humans, one endemic in birds, and two endemic in pigs (swine). Experts assume the virus "most likely" emerged from pigs in Asia, and was carried to North America by infected persons. There is also evidence that the new strain had been circulating among pigs on other continents for years before infecting humans. But transmission is human to human, with cooked pork products safe to eat as the virus cannot be transmitted by eating foods.

Avian Influenza (Bird Flu) can also infect pigs

Avian flu and human seasonal flu viruses can infect pigs, as well as swine influenza. The H3N2 influenza virus subtype, a virulent one, is thought to have come from pigs - it went on to infect humans.

It is possible for pigs to be infected with more than one flu virus subtype simultaneously. When this happens the genes of the viruses have the opportunity to mingle. When different flu subtypes mix they can create a new virus which contains the genes from several sources - a reassortant virus.
Although swine influenza tends to just infect pigs, they can, and sometimes do, jump the species barrier and infect humans.

What is the risk for human health?

Outbreaks of human infection from a virus which came from pigs (swine influenza) do happen and are sometimes reported. Symptoms will generally be similar to seasonal human influenzas - this can range from mild or no symptoms at all, to severe and possibly fatal pneumonia.

As swine flu symptoms are similar to typical human seasonal flu symptoms, and other upper respiratory tract infections, detection of swine flu in humans often does not happen, and when it does it is usually purely by chance through seasonal influenza surveillance. If symptoms are mild it is extremely unlikely that any connection to swine influenza is found - even if it is there. In other words, unless the doctors and experts are specifically looking for swine flu, it is rarely detected. Because of this, we really do not know what the true human infection rate is.

Examples of known swine flu infecting humans

Since the World Health Organization's (WHO's) implementation of IHR (2005) in 2007, they have been notified of swine influenza cases from the USA and Spain.

In March/April 2009 human cases of influenza A swine fever (H1N1) were first reported in California and Texas. Later other states also reported cases. A significant number of human cases during the same period have also been reported in Mexico - starting just in Mexico City, but now throughout various parts of the country. More cases are being reported in Canada, Europe, and New Zealand - mainly from people who have been in Mexico.

How does a human catch swine influenza?

  • From contact with infected pigs (most common way)
  • From contact with infected humans (much less common way)

In cases when humans have infected other humans close contact was necessary with the infected person, and they nearly always occurred in closed groups of people.

What does H1N1 mean ? 

Influenza viruses can be identified based on the chemical structure of specific proteins found on the outer surface coat of the virus particle. The two dominant proteins found on the virus surface are known as Hemagglutinin (often referred to as "H" or "HA") and Neuraminidase ("N" or "NA"). Both of these proteins play critical roles in the lifespan of an influenza virus.
The array of flu viruses that have been characterized over the years can carry different versions of H or N, and thus the numbering system. There are more than 10 known forms of H and as many as 9 versions of N. Thus different strains can be characterized by the type of H or N that they carry e.g. H1N1, or H3N2, etc. The avian flu that focused the world's attention several years ago was known as H5N1.

What Do the H and N Proteins Do? 

The H protein is important in allowing the virus to adhere to cells and gain entry so that the virus can be replicated. The name "hemagglutinin" means that the protein can cause red blood cells to clump together, one of the features originally associated with the flu virus when tested in laboratory dishes. The N protein, "neuraminidase", is an enzyme that helps the virus to escape from cells once new viral particles have been replicated. This enzyme can cleave specialized sugar molecules that are often associated with the proteins found on the surface of cells. This is the protein that is targeted by flu medications such as Tamiflu and Relenza.

Why the name was changed from SWINE FLU to Influenza type A subtype H1N1 by WHO ? 

You may have noticed recently that the World Health Organization and other related agencies just stopped calling the virus the "swine flu" and started calling it by its scientific name Influenza type A subtype H1N1. Some falsely believe that this was a worldwide response to cries of foul from pig farmers worried about their business, to stem the worldwide panic causing countries to slaughter pigs and the general public to have sworn off bacon and other lesser pork products. While those factors all certainly exist, in fact, this was the correct thing to do epidemiologically speaking.
"Swine flu" is just a generic term for any influenza virus that is transmitted between pigs. Once the flu crosses over to another species, like us, it's no longer a "swine flu" but a "human/dog/seal/bird flu of swine origin". So calling the current Influenza A H1N1 virus a swine flu doesn't correctly communicate the human-to-human transmissibility aspect of the virus. H1N1 has, just like in 1918, become a "human flu".

What is INFLUENZA A virus? 

There are three Influenza viruses that infect humans which include influenza A, influenza B, and influenza C. However, the influenza A virus is more commonly seen. The influenza A virus has been attributed to cause serious epidemics and pandemics.
Influenzavirus A is a genus of the Orthomyxoviridae family of viruses. Influenzavirus A includes only one species. The influenza A virus infects a wide array of species including pigs, horses, birds, humans, and other animals. Although there are many similarities between these influenza A viruses, they are by no means the same. Each influenza A virus is genetically tailored to infect that species. Influenza A viruses are negative sense, single-stranded, segmented RNA viruses. There are several subtypes, labeled according to an H number (for the type of hemagglutinin) and an N number (for the type of neuraminidase). There are 16 different H antigens (H1 to H16) and nine different N antigens (N1 to N9)
Influenza is a respiratory infection caused by an influenza virus. influenza virus may cause mild or severe illness which can lead to death.
The influenza virus In the U.S. is estimated annually to:
* Infect 5-20% of the population
* Account for 200,000 hospitalizations
* Account for 36,000 deaths

Can I eat pork meat and pork products?

If the pork meat and pork food products have been handled properly transmission of swine influenza to humans is not possible. Cooking pork meats to a temperature of 70C (160F) kills the virus. So the answer is YES, pork meat and pork food products are safe to eat.

Where have pigs been infected?

As swine influenza infection among pigs is not an internationally notifiable disease we cannot be completely sure. Swine influenza infection among pigs is known to be endemic in the USA. Outbreaks have also occurred in other parts of North America, South American, Europe, Africa, China, Japan, and other parts of Asia.

Is there a pandemic risk?

People who are not in close contact with pigs generally have no immunity to the swine influenza viruses - they are less likely to be able to prevent a virus infection. If the virus infects enough people in a given area, the risk of an influenza pandemic is significantly greater. Experts say it is very hard to predict what impact a flu pandemic caused by a swine influenza virus would have on the global human population. This would depend on how virulent the virus is, what existing immunity among humans there already is, plus several other factors.

Will current human flu vaccines help protect people from swine influenza infection?

We really don't know. Influenza viruses are adapting and changing all the time. If a vaccine was made, it would have to be specifically for a current strain that is circulating for it to be effective. The WHO says it needs access to as many viruses as possible so that it can isolate the most appropriate candidate vaccine.

What are the signs and symptoms of swine influenza in humans?

They are similar to those of regular flu, and include:

 

  • Body aches
  • Chills
  • Cough
  • Diarrhea (less common)
  • Headache
  • Sore throat
  • Temperature (fever)
  • Tiredness (fatigue)
  • Vomiting (less common)

 

What are the complications of swine flu? 

One of the most common complications of any type of flu is a secondary bacterial chest infection, such as bronchitis (infection of the airways).

This can become serious and develop into pneumonia. A course of antibiotics will usually cure this, but the infection sometimes becomes life-threatening.

Other rare complications include:

* tonsilitis,
* otitis media (a build-up of fluid in the ear),
* septic shock (infection of the blood that causes a severe drop in blood pressure),
* meningitis (infection in the brain and spinal cord), and
* encephalitis (inflammation of the brain).

Swine Flu High Risk Groups: 

With regular seasonal flu, infants and the elderly are usually thought to be most at risk for serious infections, in addition to people with chronic medical problems. Swine flu high risk groups, people who are thought to be at risk for serious, life-threatening infections, are a little different and can include:

* pregnant women
* people with chronic medical problems, such as chronic lung disease, like asthma, cardiovascular disease, diabetes, and immunosuppression
* children and adults with obesity

What medications are there?

There are some drugs around that can effectively treat swine flu infection in humans - and many types of flu infections in humans. There are two main types:

  • adamantanes (amantadine and remantadine)
  • inhibitors of influenza neuraminidase (oseltamivir and zanamivir)

Most previous swine influenza human cases recovered completely without the need for medical attention.

What can I do to protect myself?

  • Wash your hands regularly with soap
  • Try to stay healthy
  • Get plenty of sleep
  • Do plenty of exercise
  • Try to manage your stress
  • Drink plenty of liquids
  • Eat a well balanced diet
  • Refrain from touching surfaces which may have the virus
  • Do not get close to people who are sick
  • Stay away from crowded areas if there is a swine flu outbreak in your area

If I am infected, how can I stop others from becoming infected?

  • Limit your contact with other people
  • Do not go to work or school
  • When you cough or sneeze cover your mouth with a tissue. If you do not have a tissue, cover your mouth and nose.
  • Put your used tissues in a waste basket
  • Wash your hands and face regularly
  • Keep all surfaces you have touched clean
  • Follow your doctor's instructions

What You Need To Know:

* Swine flu likely spreads by direct contact with respiratory secretions of someone that is sick with swine flu, like if they were coughing and sneezing close to you.

* People with swine flu are likely contagious for one day before and up to seven days after they began to get sick with swine flu symptoms.

* Droplets from a cough or sneeze can also contaminate surfaces, such as a doorknob, drinking glass, or kitchen counter, although these germs likely don't survive for more than a few hours.

* Anti-flu medications, including Tamiflu (oseltamivir) and Relenza (zanamivir), are available to prevent and treat swine flu.

* The latest swine flu news from the CDC includes advice that children should not attend summer camps if they have had swine flu symptoms in the previous seven days and that camp staff should be quick to identify campers with swine flu symptoms and separate them from well campers.

 


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