Swine Flu

What is Swine Influenza?
Swine Influenza (swine flu) is a respiratory disease of pigs caused by type A influenza virus that regularly causes outbreaks of influenza in pigs. Swine flu viruses cause high levels of illness and low death rates in pigs. Swine influenza viruses may circulate among swine throughout the year, but most outbreaks occur during the late fall and winter months similar to outbreaks in humans. The classical swine flu virus (an influenza type A H1N1 virus) was first isolated from a pig in 1930 .

How many swine flu viruses are there?
Like all influenza viruses, swine flu viruses change constantly. Pigs can be infected by avian influenza and human influenza viruses as well as swine influenza viruses. When influenza viruses from different species infect pigs, the viruses can reassort (i.e. swap genes) and new viruses that are a mix of swine, human and/or avian influenza viruses can emerge. Over the years, different variations of swine flu viruses have emerged. At this time, there are four main influenza type A virus subtypes that have been isolated in pigs: H1N1, H1N2, H3N2, and H3N1. However, most of the recently isolated influenza viruses from pigs have been H1N1 viruses

Swine Flu in Humans

Can humans catch swine flu?
Swine flu viruses do not normally infect humans. However, sporadic human infections with swine flu have occurred. Most commonly, these cases occur in persons with direct exposure to pigs (e.g. children near pigs at a fair or workers in the swine industry). In addition, there have been documented cases of one person spreading swine flu to others. For example, an outbreak of apparent swine flu infection in pigs in Wisconsin in 1988 resulted in multiple human infections, and, although no community outbreak resulted, there was antibody evidence of virus transmission from the patient to health care workers who had close contact with the patient

How does swine flu spread?
Influenza viruses can be directly transmitted from pigs to people and from people to pigs. Human infection with flu viruses from pigs are most likely to occur when people are in close proximity to infected pigs, such as in pig barns and livestock exhibits housing pigs at fairs. Human-to-human transmission of swine flu can also occur. This is thought to occur in the same way as seasonal flu occurs in people, which is mainly person-to-person transmission through coughing or sneezing of people infected with the influenza virus. People may become infected by touching something with flu viruses on it and then touching their mouth or nose.

What do we know about human-to-human spread of swine flu?
In September 1988, a previously healthy 32-year-old pregnant woman was hospitalized for pneumonia and died 8 days later. A swine H1N1 flu virus was detected. Four days before getting sick, the patient visited a county fair swine exhibition where there was widespread influenza-like illness among the swine.

In follow-up studies, 76% of swine exhibitors tested had antibody evidence of swine flu infection but no serious illnesses were detected among this group. Additional studies suggest that one to three health care personnel who had contact with the patient developed mild influenza-like illnesses with antibody evidence of swine flu infection.

How can human infections with swine influenza be diagnosed?
To diagnose swine influenza A infection, a respiratory specimen would generally need to be collected within the first 4 to 5 days of illness (when an infected person is most likely to be shedding virus). However, some persons, especially children, may shed virus for 7 days or longer. Identification as a swine flu influenza A virus requires sending the specimen to CDC for laboratory testing.

Symptoms

The symptoms of this new H1N1 flu virus in people are similar to the symptoms of seasonal flu and include fever, cough, sore throat, runny or stuffy nose, body aches, headache, chills and fatigue. A significant number of people who have been infected with this new H1N1 virus also have reported diarrhea and vomiting.   The high risk groups for novel H1N1 flu are not known at this time but it's possible that they may be the same as for seasonal influenza. People at higher risk of serious complications from seasonal flu include people age 65 years and older, children younger than 5 years old, pregnant women, people of any age with chronic medical conditions (such as asthma, diabetes, or heart disease), and people who are immunosuppressed (e.g., taking immunosuppressive medications, infected with HIV).

Avoid Contact with Others

If you are sick, you may be ill for a week or longer. You should stay home and avoid contact with other persons, except to seek medical care. If you leave the house to seek medical care, wear a mask or cover your coughs and sneezes with a tissue. In general you should avoid contact with other people as much as possible to keep from spreading your illness. At the current time, CDC believes that this virus has the same properties in terms of spread as seasonal flu viruses. With seasonal flu, studies have shown that people may be contagious from one day before they develop symptoms to up to 7 days after they get sick. Children, especially younger children, might potentially be contagious for longer periods .

Treatment is Available for Those Who Are Seriously III

It is expected that most people will recover without needing medical care.

If you have severe illness or you are at high risk for flu complications, contact your health care provider or seek medical care. Your health care provider will determine whether flu testing or treatment is needed. Be aware that if the flu becomes wide spread, there will be little need to continue testing people, so your health care provider may decide not to test for the flu virus.

Antiviral drugs can be given to treat those who become severely ill with influenza. These antiviral drugs are prescription medicines (pills, liquid or an inhaler) with activity against influenza viruses, including H1N1 flu virus. These medications must be prescribed by a health care professional.

There are two influenza antiviral medications that are recommended for use against H1N1 flu. The drugs that are used for treating H1N1 flu are called oseltamivir (trade name Tamiflu ®) and zanamivir (Relenza ®). As the H1N1 flu spreads, these antiviral drugs may become in short supply. Therefore, the drugs will be given first to those people who have been hospitalized or are at high risk of complications. The drugs work best if given within 2 days of becoming ill, but may be given later if illness is severe or for those at a high risk for complications.

Aspirin or aspirin-containing products (e.g. bismuth subsalicylate – Pepto Bismol) should not be administered to any confirmed or suspected ill case of novel influenza A (H1N1) virus infection aged 18 years old and younger due to the risk of Reye syndrome. For relief of fever, other anti-pyretic medications are recommended such as acetaminophen or non steroidal anti-inflammatory drugs. For more information about Reye's syndrome, visit the National Institute of Health website .

•  Check ingredient labels on over-the-counter cold and flu medications to see if they contain aspirin.

•  Teenagers with the flu can take medicines without aspirin, such as acetaminophen (Tylenol®) and ibuprofen (Advil®, Motrin®, Nuprin®), to relieve symptoms.

•  Children younger than 4 years of age should not be given over-the-counter cold medications without first speaking with a healthcare provider.

Emergency Warning Signs

•  If you become ill and experience any of the following warning signs, seek emergency medical care.

•  In children emergency warning signs that need urgent medical attention include:

•  Fast breathing or trouble breathing

•  Bluish or gray skin color

•  Not drinking enough fluids

•  Severe or persistent vomiting

•  Not waking up or not interacting

•  Being so irritable that the child does not want to be held

•  Flu-like symptoms improve but then return with fever and worse cough

• 
In adults, emergency warning signs that need urgent medical attention include:

•  Difficulty breathing or shortness of breath

•  Pain or pressure in the chest or abdomen

•  Sudden dizziness

•  Confusion

•  Severe or persistent vomiting

•  Flu-like symptoms improve but then return with fever and worse cough

Protect Yourself, Your Family, and Community

•  Stay informed. Health officials will provide additional information as it becomes available. Visit the CDC H1N1 Flu website .

•  Cover your nose and mouth with a tissue when you cough or sneeze. Throw the tissue in the trash after you use it.

•  Wash your hands often with soap and water, especially after you cough or sneeze. Wet wipes containing antibacterial are also effective.

•  Avoid touching your eyes, nose or mouth. Germs spread this way.

•  Try to avoid close contact with sick people.

•  If you are sick with a flu-like illness, stay home for 7 days after your symptoms begin or until you have been symptom-free for 24 hours, whichever is longer. Keep away from other household members as much as possible. This is to keep you from infecting others and spreading the virus further.