Cold, Flu, & Cough Health Center

H1N1 Flu Virus (Swine Flu)

In April 2009, a new strain of H1N1 swine flu emerged that contained a combination of swine, avian, and human influenza viruses. In the past, swine flu had mainly affected people who had direct contact with pigs. The new virus is unusual because it has spread among people who haven't been near pigs.

H1N1 swine flu, which was first observed in Mexico, has crossed borders and oceans, spreading to different countries and continents.

Causes of Swine Flu

Swine flu is contagious, and health officials believe it spreads in the same way as the seasonal flu. When people who are infected with swine flu cough or sneeze, they release tiny droplets containing the virus into the air. Anyone who comes in contact with these droplets or touches a surface (such as a doorknob or sink) that an infected person has recently touched can catch H1N1 swine flu.

A person who has swine flu can be contagious from one day before they show symptoms to seven days after they get sick. Children can be contagious for as long as 10 days.

Despite the name of the virus, you can't catch swine flu from eating bacon, ham, or any other pork product. However, to avoid other illnesses, it is always important to cook pork until it reaches an internal temperature of 160 degrees.

Symptoms of Swine Flu

Symptoms of the swine flu are the same as those of seasonal influenza, and can include:

• cough
• fever
• sore throat
• stuffy or runny nose
• body aches
• headache
• chills
• fatigue
• nausea and vomiting 

Swine flu also can lead to more serious complications, including pneumonia and respiratory failure, and it can worsen the severity of chronic conditions like diabetes or asthma. Serious symptoms such as shortness of breath, severe vomiting, abdominal pain, dizziness, or confusion warrant an immediate call to your doctor or 911.

What is concerning about swine flu is that, unlike seasonal flu, which is typically most dangerous to the very young, elderly, and those with a weakened immune system, swine flu can also be life-threatening to young, healthy people.

Tests for Swine Flu

Because the symptoms of swine flu closely mimic those of seasonal flu, only a lab test can determine for sure whether you have the H1N1 swine flu. Rapid flu tests, done in the doctor's office, often give false negative results, so they can't be relied on to diagnose pandemic flu.

To test for swine flu, your doctor collects a sample from your nose or throat. Not everyone with suspected H1N1 swine flu needs to be tested to confirm diagnosis, according to the CDC. The CDC says priority for testing is for people who are hospitalized or have high risk for severe disease, such as:  

• Children under 5 years old
• People aged 65 or older
• Children and adolescents (under age 18) who are receiving long-term aspirin therapy and who might be at risk for experiencing Reye syndrome after influenza virus infection
• Pregnant women
• Adults and children who have chronic pulmonary, cardiovascular, hepatic, hematological, neurologic, neuromuscular, or metabolic disorders
• Adults and children who have immunosuppression (including immunosuppression caused by medications or by HIV)
• Residents of nursing homes and other chronic care facilities