Swine flu (H1N1 flu)

Technically, the term "swine flu" refers to influenza in pigs. Occasionally, pigs transmit influenza viruses to people, mainly to hog farmers and veterinarians. Less often, someone infected passes the infection to others.

The human respiratory infection caused by a particular influenza virus H1N1 strain — popularly known as swine flu — was first recognized in spring 2009. A few months after the first swine flu cases were reported, rates of confirmed H1N1-related illness were increasing in much of the world. As a result, the World Health Organization declared the infection a global pandemic.

The pandemic was declared over in August 2010. Currently, H1N1 is still circulating in humans as a seasonal flu virus and is included in the seasonal flu vaccine.

Symptoms Causes Risk factors Complications Prevention

Swine flu signs and symptoms in humans are similar to those of other flu strains:

  • Fever
  • Cough
  • Sore throat
  • Runny or stuffy nose
  • Body aches
  • Headache
  • Chills
  • Fatigue
  • Diarrhea
  • Vomiting

Swine flu symptoms develop about one to three days after you're exposed to the virus and continue for about seven days.

When to see a doctor

It's not necessary to see a doctor if you're generally healthy and develop flu signs and symptoms, such as fever, cough and body aches. Call your doctor, however, if you have flu symptoms and you're pregnant or you have a chronic disease, such as emphysema or a heart condition.

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