Swine influenza (also called swine flu, hog flu, and pig flu) refers to influenza 
caused by those strains of influenza virus that usually infect pigs and are called
swine influenza virus (SIV). Swine influenza is common in pigs in the midwestern
United States (and occasionally in other states), Mexico, Canada, South America,
Europe (including the United Kingdom, Sweden, and Italy), Kenya, Mainland China,
Taiwan, Japan and other parts of eastern Asia. 


In human, direct transmission of a swine flu virus from pigs to humans is occasionally
possible (this is called zoonotic swine flu). In all, 50 cases are known to have occurred since the
first report in the medical literature in 1958, which have resulted in a total of six deaths.
Of these six people, one was pregnant, one had leukemia, one had Hodgkin disease and
two were known to be previously healthy. Despite these apparently low numbers of infections, the true
rate of infection may be higher, since most cases only cause a very mild disease, and will probably never
be reported or diagnosed. 

According to the Centers for Disease Control and Prevention (CDC), in humans the symptoms of the 2009
 "swine flu" H1N1 virus are similar to those of influenza and of influenza-like illness in general.
Symptoms include fever, cough, sore throat, body aches, headache, chills and fatigue.
The 2009 outbreak has shown an increased percentage of patients reporting diarrhea and vomiting.
The 2009 H1N1 virus is not zoonotic swine flu, as it is not transmitted from pigs to humans, but from person
 to person.

Because these symptoms are not specific to swine flu, a differential diagnosis of probable swine flu requires
 not only symptoms but also a high likelihood of swine flu due to the person's recent history. For example,
during the 2009 Swine flu outbreak in the United States, CDC advised physicians to "consider swine influenza
infection in the differential diagnosis of patients with acute febrile respiratory illness who have either been
in contact with persons with confirmed swine flu, or who were in one of the five U.S. states that have reported
swine flu cases or in Mexico during the 7 days preceding their illness onset." A diagnosis of confirmed swine
 flu requires laboratory testing of a respiratory sample (a simple nose and throat swab).

Treatment

If a person becomes sick with swine flu, antiviral drugs can make the illness milder and make the patient
feel better faster. They may also prevent serious flu complications. For treatment, antiviral drugs work best
if started soon after getting sick (within 2 days of symptoms). Beside antivirals, palliative care, at home or in
the hospitals, focuses on controlling fevers and maintaining fluid balance. The U.S. Centers for Disease
Control and Prevention recommends the use of Tamiflu (oseltamivir) or Relenza (Zanamivir) for the
treatment and/or prevention of infection with swine influenza viruses, however, the majority of people
infected with the virus make a full recovery without requiring medical attention or antiviral drugs. The virus
isolates in the 2009 outbreak have been found resistant to amantadine and rimantadine.
Prevention in humans

Prevention of pig to human transmission

Swine can be infected by both avian and human influenza strains of influenza, and therefore are hosts
where the antigenic shifts can occur that create new influenza strains.

The transmission from swine to human is believed to occur mainly in swine farms where farmers are in
close contact with live pigs. Although strains of swine influenza are usually not able to infect humans this
may occasionally happen, so farmers and veterinarians are encouraged to use a face mask when dealing with
infected animals. The use of vaccines on swine to prevent their infection is a major method of limiting swine
to human transmission. Risk factors that may contribute to swine-to-human transmission include smoking and
 not wearing gloves when working with sick animals. 

Prevention of human to human transmission

Influenza spreads between humans through coughing or sneezing and people touching something with the
 virus on it and then touching their own nose or mouth. Swine flu cannot be spread by pork products,
since the virus is not transmitted through food. The swine flu in humans is most contagious during the first
five days of the illness although some people, most commonly children, can remain contagious for up to ten
days. Diagnosis can be made by sending a specimen, collected during the first five days for analysis. 

Recommendations to prevent spread of the virus among humans include using standard infection control
against influeza. This includes frequent washing of hands with soap and water or with alcohol-based hand
sanitizers, especially after being out in public. Although the current trivalent influenza vaccine is unlikely to
provide protection against the new 2009 H1N1 strain, vaccines against the new strain are being developed
and could be ready as early as June 2009. 

Experts agree that hand-washing can help prevent viral infections, including ordinary influenza and the
swine flu virus. Influenza can spread in coughs or sneezes, but an increasing body of evidence shows small
droplets containing the virus can linger on tabletops, telephones and other surfaces and be transferred via
the fingers to the mouth, nose or eyes. Alcohol-based gel or foam hand sanitizers work well to destroy viruses
and bacteria. Anyone with flu-like symptoms such as a sudden fever, cough or muscle aches should stay away
from work or public transportation and should contact a doctor to be tested.