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Background

Seasonal Influenza

The flu is a contagious respiratory illness caused by influenza viruses. It can cause mild to severe illness, and at times can lead to death. The best way to prevent seasonal flu is by getting a seasonal flu vaccination each year.

Every year in the United States, on average:

• 5% to 20% of the population gets the flu;
• more than 200,000 people are hospitalized from flu-related complications; and
• about 36,000 people die from flu-related causes.

Some people, such as older people, young children, pregnant women and people with certain health conditions (such as asthma, diabetes, or heart disease), are at increased risk for serious complications from seasonal flu illness.

Symptoms of seasonal flu include:

• fever (often high)
• headache
• extreme tiredness
• dry cough
• sore throat
• runny or stuffy nose
• muscle aches
• Stomach symptoms, such as nausea, vomiting, and diarrhea, also can occur but are more common in children than adults. Some people who have been infected with the new H1N1 flu virus have reported diarrhea and vomiting.

(Source: CDC)

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2009 H1N1 Influenza

2009 H1N1 (sometimes called "swine flu”) is a new influenza virus causing illness in people. This new virus was first detected in people in the United States in April 2009. This virus is spreading from person-to-person worldwide, probably in much the same way that regular seasonal influenza viruses spread. On June 11, 2009, the World Health Organization (WHO) declared that a pandemic of 2009 H1N1 flu was underway.

The symptoms of 2009 H1N1 flu virus in people include fever, cough, sore throat, runny or stuffy nose, body aches, headache, chills and fatigue. Some people may have vomiting and diarrhea. People may be infected with the flu, including 2009 H1N1 and have respiratory symptoms without a fever. Severe illnesses and deaths have occurred as a result of illness associated with this virus. (Source: CDC)

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Avian Influenza (H5N1)

Although avian influenza A viruses usually do not infect humans, rare cases of human infection with avian influenza A viruses have been reported. Most human infections with avian influenza A viruses have occurred following direct contact with infected poultry. Human clinical illness from infection with avian influenza A viruses has ranged from eye infections (conjunctivitis) to severe respiratory disease (pneumonia) to death.

Since November 2003, nearly 400 cases of human infection with highly pathogenic avian influenza A (H5N1) viruses have been reported by more than a dozen countries in Asia, Africa, the Pacific, Europe and the Near East. Highly pathogenic avian influenza A (H5N1) viruses have never been detected among wild birds, domestic poultry, or people in the United States.Most human cases of H5N1 virus infection are thought to have occurred as a result of direct contact with sick or dead infected poultry.

The reported signs and symptoms of avian influenza in humans have ranged from eye infections (conjunctivitis) to influenza-like illness symptoms (e.g., fever, cough, sore throat, muscle aches) to severe respiratory illness (e.g. pneumonia, acute respiratory distress, viral pneumonia) sometimes accompanied by nausea, diarrhea, vomiting and neurologic changes. (Source: CDC)

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