How is swine flu caused?

Answer 1

It was caused by a particular strain of the influenza virus, just like any other flu. This particular strain A-H1N1/09 (aka: Influenza A, Novel H1N1 or 2009 Swine Flu virus) originated in pigs (swine) but has changed itself to be infective to humans.

Swine flu is a virus that originally infected only pigs and they spread it from one infected hog to other hogs the same way it spreads in people, by direct contact or by droplets holding the virus in the air after a pig coughed or sneezed. Because pigs are physiologically very similar to humans, when they have been living closely with humans, some microbes that can infect them are able to be changed or mutated into strains that people can catch. These types of diseases that we can get from animals are called zoonotic diseases.

Pigs contract swine flu from other infected swine, particularly in pigpens and herding areas. Flu viruses from birds and people may also infect pigs. Swine influenza passes quickly among pigs, and can cause major losses for pig farmers because of the rate of illness. It is now also possible for infected people to pass swine flu back to other pigs.

Usually viruses that infect one kind of animal do not often infect others. However, if the animals are kept very closely together, it is more likely that mutations can occur that allow new strains to develop with the ability to cross from one type of animal to another. Viruses can mutate very rapidly. Since they are non-living sub-microscopic organisms (microbes), and not actually living organisms (like bacteria and microscopic fungi), they can combine with the cells of host animals and change the genetic material in those host cells to reproduce themselves. Sometimes that assimilation can also change the makeup to a new strain of virus (sub-microscopic particle microbe) which is then replicated by the damaged cells as well.

This cross-family type of mutation is called a reassortant, or sometimes reassortment, of genetic material in viruses. It has happened in the past when ducks or other birds were kept very closely together with pigs. That is how the Avian (bird) flu became a problem for people. First bird flu was mutated to a strain that could be caught by the pigs they were closely around. Once infecting the pigs, other mutations occurred that allowed their bird flu-swine crossed viruses to mutate again to viruses that people who were in close contact with the pigs infected with the bird-swine virus could catch. This kind of "cross-contamination", through mutations of the viruses infecting the physiologically similar pigs, allows new strains to develop to which people have no inherited immunity (passed down from generation to generation) or prior exposure to a similar type that would have given them cross protection.

It is considered potentially more dangerous than other types of influenza because the human population has not experienced this particular kind of Swine flu before. Therefore, it is anticipated that there will be few people with any natural resistance to it, whereas most people usually have some resistance to other strains of influenza once they are 10 years old or older. As a result of the lack of resistance, it can spread more easily and perhaps produce more severe symptoms.

The 2009 Swine Flu was doubly difficult for us to create effective vaccines (which would help to teach our immune systems how to fight the virus). This is because the new strain of virus mutated within the pigs where it could first merge genetic materials of the bird viruses and swine viruses that the pigs had been exposed to and then it become infective to humans as well, from the additional close contact of pigs and humans who cared for them (triple reassortant). The reassortant process within the pigs combined the pig genetic material, the bird genetic material, and also human genetic material. The 2009 Pandemic Swine Flu virus (A-H1N1/09) contains genetic material that is from the bird flu as well as from three swine flu virus strains (Asian, American, and European), plus the human flu virus ("quintuple reassortant"). We would have had an easier time developing our vaccine for this flu virus if it had been formed from one or the other, and not with the five types of genetic material that it currently contains. As it is, we had to start "from scratch" to grow the right kind of virus to put into the vaccines.

The whole process of infections can also work back the other way. So now we humans can get swine flu from each other, from infected pigs, and we can give it to pigs who can infect each other. In other words, because aspects of human viral strains are incorporated into the animal viral strains using the pig as a "middle man", newer viruses are developed that are able to cross the animal family boundaries.

Over crowding, of people with each other and with pigs, and pigs with each other and with other animals, are the major reasons these "reassortant" viruses can occur.

Farmers who work with swine must use very clean techniques to avoid catching and transmitting the swine flu. The CDC has guidelines for people who have these jobs or spend time around hogs, such as showing them in breed competitions. See the links below.

As with any virus, very good hygiene, including thorough hand washing, is critical after contact or close proximity.

See the related questions for steps to take to avoid contracting this virus.

Answer 2

How Is A-H1N1/09 (Pandemic "Swine Flu") Spread in Humans?Like most viruses, it enters the body through the mucous membranes - the eyes, the nose or the mouth. Swine flu is spread just like the regular seasonal flu spreads. It goes from person to person through close contact and direct touch, indirect touch, or respiratory droplets carrying the virus from person to person or from person to environmental surfaces through coughs and sneezes.

If you touch where a person with swine flu touches, you will most likely pick up the virus and get the swine flu. That is how it spreads indirectly. Stay a minimum of six feet away from someone with a known infection, avoid close contact from crowded places.

You get direct spreading when you have skin to skin contact or direct person to person contact with an infected individual, such as shaking hands, kissing, or caring for a child or other infected person with hands-on care. You could be infected by getting too close to someone who has it. Do not hug people who have the swine flu. Wait for them to recover, then hug them.

Do not share drinking glasses or eating utensils with someone, this can also spread the disease. There is some evidence to suggest that it can be spread through gastrointestinal means, such as saliva, emesis (vomit), and feces (stool). The importance of hand washing before and after eating, using the restroom, or providing personal care to an infected individual must be stressed. Teach your family proper hand washing technique. (See related question for this information).

Flu viruses can also be spread by handling money. See the related question below.

What Are Some Ways It Is NOT Spread?Swine flu is not spread by eating pork. Flu viruses are inactivated ("killed") by heating to temperatures of 167-212°F [75-100°C].

Swine flu has not been shown to be spread by drinking tap water that has been provided by a local municipality (regular drinking water).

Swine flu is not spread through swimming in chlorinated pools, or by being in the water at recreational water parks that regularly treat the water. It is not spread in fountains that use purified water or spas. There is some risk of catching it at beaches, or at recreational water theme parks from people among the crowds and not in the treated water, just as in any other crowded public place.

How Can the Spread Be Controlled?Protect yourself and others by getting your flu vaccination, it is the most important and most effective way to stay well and to avoid spreading the flu to your family, coworkers, and in public. It has been proven to be safe and effective during the 2009 flu season, and since it is made exactly like the flu vaccines in prior years, it has been proven safe and effective over decades of use.

Another very important method of prevention is proper and frequent hand washing and regular hygiene. To help prevent swine flu, wash your hands frequently with soap and water, and avoid touching your face, eyes, nose, and mouth. When you have the virus on your hands and touch the tissues in those places, that is how the virus enters your body.

See the related question below for additional information about protecting yourself from contracting this and other viruses. The most important protection is basic hand washing and hygiene as described in the related question below. If no warm water and soap is available for hand washing, the hand sanitizers with at least 60% alcohol content can be used (or even plain rubbing alcohol).

How Long Can You Spread It When Infected?There are still studies in progress to determine the best answer to this question. The most conservative suggestion from studies by the Department of Homeland Security (DHS), on how long a person remains contagious, seem to back up the initially reported CDC guidelines that one should be suspected to be capable of still spreading the Novel Swine Flu for one full week after the symptoms start or until 24 hours after the fever subsides [while taking no fever reducers] whichever is longer.

However, the most recent CDC guidelines indicate that waiting for 24 hours after fever subsides without taking fever reducers is long enough.

According to the 9/19/09 DHS report:

Swine flu also appears to be contagious longer than ordinary seasonal flu, several experts said.

When the coughing stops is probably a better sign of when a swine flu patient is no longer contagious, experts said after seeing new research that suggests the virus can still spread many days after a fever goes away.

Using a very sensitive test to detect virus in the nose or throat, [the study] found that 80 percent had it five days after symptoms began, and 40 percent seven days after. Some still harbored virus as long as 16 days later. How soon they started on antiviral medicines such as Tamiflu made a difference in how much virus was found, but not whether virus was present at all. . .

Doctors know that people can spread ordinary seasonal flu for a couple of days before and after symptoms start by studying virus that patients shed in mucus. The first such studies of swine flu are just coming out now, and they imply a longer contagious period for the novel bug.

Where Has It Spread?Everywhere. It has infected people in every country of the world.

This pandemic virus from 2009 (A-H1N1/09) spread faster than any other flu in the past and to every country in the world. It is now (Oct 2010) in the "Post Pandemic Phase" but it continues to be active in small outbreaks in some countries.

The World Health Organization (WHO) has developed an interactive map showing the time line and progression of the spread of the Novel H1N1 across the world during the early phases of the pandemic. A link is provided to the map in the related links section below, a flash player is needed to view the map.

How Does It Spread In Swine (Pigs)?The following answer is about the strain of H1N1 influenza that pigs get that is not the same as A-H1N1/09 pandemic flu:

Swine Flu can be transmitted from a pig to a human, like the human flu passes to humans. For example, if a human touches the pig or something a pig that has swine flu sneezes or coughs on, and then touches his face, mouth, nose or eyes before washing his hands, that farmer could then get the swine flu that pigs get. It is rare, but it does happen every year, mainly to pig farmers.

More Information?For more information about how the Pandemic Swine Flu A-H1N1/09 is spread, see the related questions below, links below, and browse the H1N1 Pandemic Swine Flu category for answers to hundreds of questions and answers. Or for encyclopedic reference material about the flu, see the Answers.com Reference Library.

Answer 3

They usually catch it directly from coughs and sneezes of other pigs in close quarters with them or from objects that the cough or sneeze has infected.

For information on what initially caused the 2009 H1N1 swine flu to develop, see the related question below.

Answer 4

Influenza is passed through direct contact with the pigs or their saliva, respiratory droplets from coughing or sneezing, or from their digestive tracts through vomit or feces, just like it passes from person to person. If the virus is on a pig after another pig sneezed on it, and the pig then is in physical contact with a human, such as a farm worker, the virus can be passed on to the human if it is a mutated form that people can get (some strains of swine flu are more easily caught by humans than other strains).

Pigs are very much like humans physiologically and that is how their viruses have been able to mutate to strains that people can get. See the related question below for more information about how this mutation caused the new pandemic virus (A-H1N1/09) that is especially easily transmitted from person to person.

Answer 5

Swine flu is the common name given to a new strain of influenza (flu). It is called swine flu because it is thought to have originated in pigs, but this is not certain.

People with swine flu typically have a fever or high temperature (over 38°C) and may also have aching muscles, sore throat and/or a dry cough. In other words, the symptoms are very similar to seasonal (regular) flu. Most people recover within a week, even without special treatment.

But as per today, swine flu has no tratment, except death

Answer 6

Swine flu viruses cause influenza symptoms (see the related question for additional information about the symptoms of influenza), and in some people, it can cause severe respiratory disease with complications and even death.

Answer 7

By sick a$$ pigs that live in the Mexico region.

Answer 8

Much the same way most viruses are contracted. Google it. ^_^