DefinitionBy Mayo Clinic Staff
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 with swine flu 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 protection against this strain was included in the seasonal flu vaccine for 2015-16. Another strain, H3N2 emerged in humans in 2011.
Aug. 13, 2015
- Key facts about human infections with variant viruses (swine origin influenza viruses in humans). Centers for Disease Control and Prevention. http://www.cdc.gov/flu/swineflu/keyfacts-variant.htm. Accessed May 31, 2015.
- Thorner AR. Epidemiology of pandemic H1N1 influenza ('swine influenza'). http://www.uptodate.com/home. Accessed May 27, 2015.
- What you should know for the 2014-2015 influenza season. Centers for Disease Control and Prevention. http://www.cdc.gov/flu/about/season/flu-season-2014-2015.htm. Accessed May 31, 2015.
- Bennett JE, et al. Influenza (including avian and swine influenza). In: Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 8th ed. Philadelphia, Pa.: Saunders Elsevier; 2015. https://www.clinicalkey.com. Accessed May 27, 2015.
- The flu: What to do if you get sick. Centers for Disease Control and Prevention. http://www.cdc.gov/flu/takingcare.htm. Accessed May 31, 2015.
- Thorner AR. Treatment and prevention of pandemic H1N1 influenza ('swine influenza'). http://www.uptodate.com/home. Accessed May 27, 2015.
- Jefferson T, et al. Neuraminidase inhibitors for preventing and treating influenza in healthy adults and children. Cochrane Database of Systematic Reviews. http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD008965.pub4/abstract. Accessed May 27, 2015.
- A guide to safe use of pain medicine. U.S. Food and Drug Administration. http://www.fda.gov/ForConsumers/ConsumerUpdates/ucm095673.htm. Accessed May 31, 2015.
- Live attenuated influenza vaccine [LAIV] (The nasal spray vaccine). Centers for Disease Control and Prevention. http://www.cdc.gov/flu/about/qa/nasalspray.htm. Accessed May 27, 2015.
- Centers for Disease Control and Prevention, et al. Prevention and control of influenza with vaccines: Recommendations of the advisory committee on immunization practices, United States, 2015-16 influenza season. MMWR. 2015;64:818. http://www.cdc.gov/mmwr. Accessed Aug. 10, 2015.