Influenza (the flu) is a contagious respiratory illness that can cause mild to severe illness, and at times can lead to death. There are two main types of flu viruses: Types A and B. These viruses routinely spread in people (human influenza viruses) and are responsible for seasonal flu epidemics each year.

Pandemic Influenza

A disease epidemic occurs when there are more cases of that disease than normal. A pandemic is a worldwide epidemic of a disease with high rates of illness and death. An influenza pandemic may occur when a new influenza virus appears against which the human population has no immunity, as occurred in the spring of 2009 when a new influenza A (H1N1) virus emerged to cause illness in people and spread worldwide.

Pandemics are different than seasonal flu outbreaks. Seasonal flu outbreaks are caused by small changes in influenza viruses that people have already been exposed to. A new flu vaccine is developed each year to protect people against the expected changes in existing viruses. That’s why annual flu shots are needed and are effective. Flu season in the U.S. occurs in the fall and winter. A flu vaccine is your best protection against seasonal flu.

Swine Influenza/ Swine flu

Swine Influenza is a respiratory disease of pigs caused by type A influenza viruses that regularly cause outbreaks of influenza in pigs. Swine flu viruses can cause high levels of illness in swine herds, but usually cause few deaths. Swine flu viruses do not normally infect humans. However, sporadic human infections with swine flu have occurred. Most commonly, these cases occur in persons exposed to infected pigs.

Influenza viruses that infect pigs are different from human influenza viruses. Because pigs are susceptible to avian, human and swine influenza viruses, they potentially may be infected with influenza viruses from different species at the same time. If this happens, it is possible for the genes of these viruses to mix and create a new virus that can spread easily from person-to-person. If this new virus causes illness in people and can be transmitted easily from person to person, an influenza pandemic can occur. This is what occurred in 2009 when an influenza A H1N1 virus with swine, avian and human genes emerged in the Spring of 2009 and caused the first global pandemic in more than 40 years.

Avian Influenza/ Bird Flu/ H5N1

Avian influenza refers to a large group of different influenza viruses that cause naturally occurring respiratory infection in birds. Bird flu is common in birds all over the world and can spread when healthy birds are in contact with infected ones. On rare occasions, these bird viruses can infect other species, including pigs and humans. The vast majority of avian influenza viruses do not spread easily to humans.

An influenza pandemic happens when a new subtype emerges that has not previously circulated in humans. For this reason, avian H5N1 is a strain with pandemic potential. An H5N1 pandemic would occur if the virus adapts to humans.

Help protect yourself and your family from infections by taking these basic steps:

  • Keep your hands clean.
  • Use alcohol-based hand sanitizer if soap and water are not available.
  • Cover coughs and sneezes with a tissue or your upper sleeve, not your hands!
  • Get a yearly flu vaccine.
  • If you’re sick, stay at home! Rest and drink plenty of fluids.
  • Practice food safety by carefully cleaning utensils and surfaces with soap and hot water.
  • Stay informed of news on influenza and vaccines.

For more information about influenza and pandemics, refer to the following websites: