In 2009, the Center for Disease Control and Prevention (CDC) declared the appearance of H1N1 — popularly known as swine flu — a national health emergency. The health emergency was declared over in June 2010, but the H1N1 virus may still spread just like any seasonal flu. Severe cases of H1N1 have resulted in hospitalization and death, but the illness is treatable and preventable with a flu vaccine.

Influenza, known as the flu, is a contagious respiratory illness that may manifest as a mild sickness or escalate into a life-threatening disease. The influenza virus has been around for centuries, but the H1N1 strain appeared in 2009. Commonly referred to as swine flu, H1N1 was originally believed to be the same virus found in North American pigs, but scientists have discovered that the two viruses are very different. The H1N1 virus is transmitted through human contact, usually through airborne means such as talking, coughing or sneezing. Once an individual has had H1N1, he or she will most likely develop an immunity to that particular type of the flu.

The symptoms of H1N1 are generally identical to the primary symptoms of any seasonal flu. Common symptoms include: fever, chills, cough, sore throat, fatigue and a runny or stuffy nose. In some cases, diarrhea and vomiting can occur. An infected individual may also feel headaches or body aches. Not all cases of the flu will present a fever.

The flu typically enters the body through an influenza virus. In order to survive, the virus finds a host cell in the body to help it multiply. The virus uses your body’s usual mechanisms for generating new cells and manipulates those tools into producing more viruses. Once new viruses are created, they usually cause harm to the host cell. The H1N1 virus typically infects typically infects the cells in your respiratory system. Your immune system combats these viruses, and vaccinations trigger a heightened immune response.

The H1N1 virus circulates in certain pigs, but infection occurs in human contact. Eating pork does not cause H1N1. The virus causes a seasonal flu, which generally occurs in the fall and appears throughout the early spring.

Most people who do contract the flu will experience it mildly. Medical intervention is usually unnecessary and experts highly recommend staying at home to prevent contagion. The usual means of fighting a cold can help combat a flu, including bed rest and drinking plenty of fluids. Common remedies are available to treat fever, such as cool compresses or over-the-counter medications. Humidifiers or cough medicine can soothe painful coughing. If the case progresses seriously enough to warrant medical intervention, a doctor may prescribe antiviral medications.

Some individuals are at greater risk for developing life-threatening cases of the flu. Pregnant women, children under the age of 5 and senior citizens are more susceptible to serious illness. People with underlying health conditions such as asthma, neurological conditions, chronic lung disease or heart disease should stay particularly vigilant. A weakened immune system can also lead to grave flu complications. For more information, visit the U.S. government’s website at www.flu.gov.