In pigs, a<unk>  infection produces fever, lethargy, sneezing, coughing, difficulty breathing and decreased appetite. In some cases the infection can cause miscarriage. Although mortality is usually low (around 1–4%), the virus can produce weight loss and poor growth, causing economic loss to farmers. Infected pigs can lose up to 12 pounds of body weight over a three- to four-week period.<unk>  have receptors to which both avian and mammalian influenza viruses are able to bind; this leads to the virus being able to evolve and mutate into different forms. Influenza A is responsible for infecting<unk> , and was first identified in the summer of 1918. Pigs have often been seen as "mixing vessels", which help to change and evolve strains of disease that are then passed on to other mammals, such as humans. Humans Main symptoms of<unk>  flu in humans Direct transmission of a<unk>  flu virus from pigs to humans is occasionally possible (zoonotic<unk>  flu). In all, 50 cases are known to have occurred since the first report in 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's lymphoma and two were known to be previously healthy. One of these had unknown whereabouts. 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. In this video, Dr. Joe Bresee, with CDC's Influenza Division, describes the symptoms of<unk>  flu and warning signs to look for that indicate the need for urgent medical attention. See also: See this video with subtitles on YouTube According to the United States Centers for Disease Control and Prevention (CDC), in humans the symptoms of the 2009<unk>  flu" H1N1 virus are similar to influenza and influenza-like illness in general. Symptoms include fever, cough, sore throat, watery eyes, body aches, shortness of breath, headache, weight loss, chills, sneezing, runny nose, coughing, dizziness, abdominal pain, lack of appetite, and fatigue. The 2009 outbreak showed an increased percentage of patients reporting diarrhea and vomiting as well. The 2009 H1N1 virus is not zoonotic<unk>  flu, as it is not transmitted from pigs to humans, but from person to person through airborne droplets. Because these symptoms are not specific to<unk>  flu, a differential diagnosis of probable<unk>  flu requires not only symptoms, but also a high likelihood of<unk>  flu due to the person's recent and past medical history. For example, during the 2009<unk>  flu outbreak in the United States, the CDC advised physicians to "consider<unk>  infection in the differential diagnosis of patients with acute febrile respiratory illness who have either been in contact with persons with confirmed<unk>  flu, or who were in one of the five U.S. states that have reported<unk>  flu cases or in Mexico during the seven days preceding their illness onset." A diagnosis of confirmed<unk>  flu requires laboratory testing of a respiratory sample (a simple nose and throat swab). The most common cause of death is respiratory failure. Other causes of death are pneumonia (leading to sepsis), high fever (leading to neurological problems), dehydration (from excessive vomiting and diarrhea), electrolyte imbalance and kidney failure. Fatalities are more likely in young children and the elderly.
Swine influenza
Spanish flu
Influenza 
Influenza
Bird Flu
London flu
Freshers' flu
Hong Kong flu