Definition: Defining the Meaning of H1N1 (Swine Flu)
H1N1 flu is also known as swine flu. It's called swine flu because in the past, the people who caught it had direct contact with pigs. That changed several years ago, when a new virus emerged that spread among people who hadn't been near pigs.
Influenza A (H1N1) virus is the subtype of influenza A virus that was the most common cause of human influenza (flu) in 2009. It is an Orthomyxovirus that contains the glycoproteins haemagglutinin and neuraminidase. For this reason, they are described as H1N1, H1N2 etc. depending on the type of H or N antigens they express. Haemagglutinin causes red blood cells to clump together and binds the virus to the infected cell. Neuraminidase are a type of glycoside hydrolase enzyme which help to move the virus particles through the infected cell and assist in budding from the host cells. Some strains of H1N1 are endemic in humans and cause a small fraction of all influenza-like illness and a small fraction of all seasonal influenza. H1N1 strains caused a small percentage of all human flu infections in 2004-2005. Other strains of H1N1 are endemic in pigs (swine influenza) and in birds (avian influenza).
The Sporadic H1N1 Swine Influenza virus (SIV) infection that people can experience has the potential to produce a number of clinical signs and symptoms. Numbers of the persons with a history of the SIV infection have a history of a recent, physical contact with pigs before becoming ill; although close proximity without direct contact with pigs has also been reported among persons with SIV. Contact between persons that has been either limited or non-sustained between people has lead to transmission of SIV and has been documented through published literature. Additionally; there have been confirmed cases of SIV that have not occurred through exposure to pigs.
Symptoms of Swine Flu
Many times, people experience symptoms such as a cough, fever, or sore throat; although symptoms like mild respiratory illness to include nasal congestion without a fever, or occasional severe disease have also been reported. Additional symptoms that have been reported by people with swine flu include diarrhea, vomiting, headache, myalgia, dyspnea, fatigue, and chills. Some people have experienced conjunctivitis, although it is rare. More severe disease to include pneumonia and respiratory failure have also been reported in association with swine flu. A consideration in regards to SIV involves the exacerbation of other, underlying and chronic medical conditions that a person may experience, or invasive bacterial infections.
Clinical Care and Collection of Respiratory Specimens
People who either have, or are suspected or having the SIV virus, should be considered potentially contagious for a period of seven days from the date of illness onset. People who continue to exhibit symptoms of illness for a period of time that extends past seven days should be considered contagious until their symptoms have resolved. Children; younger children in particular, have the potential to remain contagious for longer periods of time. The current outbreak of SIV is affecting younger adults between the ages of twenty and forty years of age. The time a person may remain infectious various according to the strain of swine flu involved.
Defining Swine Flu Cases
A confirmed case of SIV is defined as a person who is experiencing an acute respiratory illness combined with laboratory confirmation of the SIV virus through one of the following tests:
- Real-time RT-PCR
- Viral culture
- Four-fold rise in swine influenza A virus specific neutralizing antibodies
Suspected cases of SIV are defined as persons who are experiencing respiratory illness who may have had close contact with someone with a confirmed case of SIV while that person was ill or is an acutely ill person, such as someone with an acute respiratory illness, or contact with a person who has a history of recent contact with an animal with either a confirmed or suspected SIV infection. 'Close contact,' is defined as being within a proximity of six feet of someone who has a confirmed case of SIV. An, 'Acute Respiratory Illness,' is defined as the recent onset of at least two of the following things:
- Nasal congestion
- Sore throat
- Cough; with or without a fever or feverishness
Healthcare Worker Recommendations
When interviewing persons who are either suspected of having, or are confirmed with the SIV virus, it is recommended to:
- Keep a distance of at least 6 feet from the ill person; or use
- Personal protective equipment: fit-tested N95 respirator. If this respirator is unavailable, wear a medical-surgical mask.
When collecting respiratory specimens from an ill confirmed or suspected swine influenza A virus case, the following is recommended:
- Wear a fit-tested disposable N95 respirator or a medical-surgical mask, disposable gloves, gown, and goggles.
- When completed, place all PPE in a bio-hazard bag for appropriate disposal.
- Wash your hands thoroughly with soap and water or alcohol-based hand gel.
Recommended Infection Control for a non-hospitalized patient in an Emergency Room, Clinic or Home Visit:
Separate the person in a single room, if available, until the person is asymptomatic. If the ill person needs to move to another part of the house, they should wear a mask. The ill person should be encouraged to wash their hands frequently and to follow respiratory hygiene practices. Cups and other utensils that have been used by the ill person should be thoroughly washed with soap and water before they are used by other persons.
Infection Control for a hospitalized patients involves the following procedures:
- Use an airborne infection isolation room (AIIR) with negative pressure air handling, if available; otherwise use a single patient room with the door kept closed.
- For suctioning, bronchoscopy, or intubation, use a procedure room with negative pressure air handling.
- Standard, Droplet and Contact precautions for 7 days after illness onset or until symptoms have resolved.
- In addition, personnel should wear N95 respirators when entering the patient room.
Treatment With Antivirals
Treating either confirmed or suspected cases of swine flu with antivirals can include the use of either Zanamivir (Relenza) or Oseltamivir (Tamiflu). Recommendations regarding the use of antivirals can change as information on their susceptibilities becomes available.
Antiviral treatment for confirmed or suspected ill case of swine influenza virus infection may include either oseltamivir (Tamiflu) or zanamivir, with no preference given at this time. Recommendations for use of antivirals may change as data on antiviral susceptibilities become available. It is important to initiate the treatment as soon as possible after the onset of symptoms. Confirmed and suspected cases of SIV should be monitored for fever and respiratory symptoms for a period of seven days after their last known exposure to a person with a confirmed case of SIV infection.
Dr. Christine Nevin-Woods, executive director of the Pueblo City-County Health Department, has presented a list of actions that people can take in order to stay healthy during during any outbreaks of swine flu. These actions include:
- Wash your hands often with soap and water, especially after you cough or sneeze. Alcohol-based hands cleaners are also effective.
- Cover your nose and mouth with a tissue when you cough or sneeze. Throw the tissue in the trash after you use it.
- Avoid touching your eyes, nose or mouth. Germs spread that way.
- Try to avoid close contact with sick people.
- Influenza is thought to spread mainly person-to-person through coughing or sneezing of infected people.
- If you are sick, stay home from work or school and limit contact with others to keep from infecting them.
Preparedness and stockpiling may be needed if an illness is near or in your area. Social distancing is implemented to reduce the spread of the illness. Social distancing may be used to prevent large crowds of people from gathering. For example, schools and shopping centers may be closed; sporting events or other special events may be canceled in order to protect the community from spreading illness.
Flu & H1N1 Vaccine Awareness
There are two different types of flu vaccines, trivalent and quadrivalent.
Trivalent vaccines protect against 3 strains of the flu, A/H3N2, A/H1N1, and influenza B. Trivalent vaccines are available in:
- Traditional flu shots, approved for anyone 6 months and older.
- Intradermal shots, which use a shorter needle, approved for anyone 18-64.
- High dose shots approved for people over 65.
- Cell based shots created using viruses grown in animal cells and approved for anyone over 18.
- Recombinant shots created using DNA technology, approved for people 18-49 with severe egg allergies.
Quadivalent vaccines protect against 4 strains of the flu, A/H3N2, A/H1N1, and 2 strains of influenza B. Quadrivalent vaccines are available in:
- Traditional flu shots, approved for anyone 6 months and older.
- Nasal spray, approved for healthy people from 2-49, except pregnant women.
Quick Facts: Swine Flu (H1N1)
- Despite the name, you can't catch swine flu from eating bacon, ham, or any other pork product.
- It's hard to tell whether you have swine flu or seasonal flu, because most symptoms are the same. People with swine flu may be more likely to feel nauseous and throw up than people who have seasonal flu. But a lab test is the only way to know for sure.
- Swine flu is contagious, and it spreads in the same way as the seasonal flu. When people who have it cough or sneeze, they spray tiny drops of the virus into the air. If you come in contact with these drops or touch a surface (such as a doorknob or sink) that an infected person has recently touched, you can catch H1N1 swine flu.
- People who have swine flu can be contagious one day before they have any symptoms, and as many as 7 days after they get sick. Kids can be contagious for as long as 10 days.
Statistics: H1N1 Deaths
- The March 21, 2010 worldwide update, by the U.N.'s World Health Organization (WHO), states that "213 countries and overseas territories/communities have reported laboratory confirmed cases of pandemic influenza H1N1 2009, including at least 16,931 deaths."
- As of May 30, 2010, worldwide update by World Health Organization(WHO) more than 214 countries and overseas territories or communities have reported laboratory confirmed cases of pandemic influenza H1N1 2009, including over 18,138 deaths.