What is swine flu?
Swine Influenza (swine flu) is a respiratory disease of pigs caused
by type A influenza virus that regularly causes outbreaks of influenza
in pigs. People do not normally get swine flu, but human infections can
and do happen. Swine flu viruses have been reported to spread from
person-to-person, but in the past, this transmission was limited and not
sustained beyond three people. 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.
Do I really need to
be that worried?
How serious is swine flu infection?
Like seasonal flu, swine flu in humans can vary in severity from mild
to severe. Between 2005 until January 2009, 12 human cases of swine flu
were detected in the U.S. with no deaths occurring. However, swine flu
infection can be serious. In September 1988, a previously healthy
32-year-old pregnant woman in Wisconsin was hospitalized for pneumonia
after being infected with swine flu and died 8 days later. A swine flu
outbreak in Fort Dix, New Jersey occurred in 1976 that caused more than
200 cases with serious illness in several people and one death.
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
create 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.
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.
Are there documented cases of human infections with swine flu
in the U.S.?
In late March and early April 2009, cases of human infection with
swine influenza A (H1N1) viruses were first reported in Southern
California and near San Antonio, Texas. Other U.S. states have reported
cases of swine flu infection in humans and cases have been reported
internationally as well. An updated case count of confirmed swine flu
infections in the United States is kept at http://www.cdc.gov/swineflu/investigation.htmCDC
and local and state health agencies are working together to investigate
this situation.
How common is swine flu infection in humans?
In the past, CDC received reports of approximately one human swine
influenza virus infection every one to two years in the U.S., but from
December 2005 through February 2009, 12 cases of human infection with
swine influenza have been reported.
Is this swine flu virus contagious?
CDC has determined that this swine influenza A (H1N1) virus is
contagious and is spreading from human to human. However, at this time,
it is not known how easily the virus spreads between people.
What are the signs and symptoms of swine flu in people?
The symptoms of swine flu in people are similar to the symptoms of
regular human “seasonal influenza” and include fever, cough, sore
throat, body aches, headache, chills and fatigue. Some people have
reported diarrhea and vomiting associated with swine flu. In the past,
severe illness (pneumonia and respiratory failure) and deaths have been
reported with swine flu infection in people. Like seasonal flu, swine
flu may cause a worsening of underlying chronic medical
conditions.
How do I keep from
getting infected?
How does swine flu spread?
Spread of this swine influenza A (H1N1) virus is thought to be
happening in the same way that seasonal flu spreads. 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. Flu viruses are spread mainly from
person to person through coughing or sneezing of people with influenza.
Sometimes people may become infected by touching something with flu
viruses on it and then touching their mouth or nose.
How can someone with the flu infect someone else?
Infected people may be able to infect others beginning 1 day before
symptoms develop and up to 7 or more days after becoming sick. That
means that you may be able to pass on the flu to someone else before you
know you are sick, as well as while you are sick.
Can I get swine influenza from eating or preparing pork?
No. Swine influenza viruses are not spread by food. You cannot get
swine influenza from eating pork or pork products. Eating properly
handled and cooked pork products is safe.
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 10 days or longer.
Identification as a swine flu influenza A virus requires sending the
specimen to CDC for laboratory testing.
If I received my seasonal influenza vaccine in the fall, am I
protected?
No. The H1N1 swine flu viruses are antigenically very different from
human H1N1 viruses and, therefore, vaccines for human seasonal flu would
not provide protection from H1N1 swine flu viruses. Vaccines are
available to be given to pigs to prevent swine influenza. There is no
vaccine to protect humans from swine flu. The current swine flu H3N2
viruses are closely related to human H3N2 viruses. The seasonal
influenza vaccine will likely help provide partial protection against
swine H3N2, but not swine H1N1 viruses.
Are there medicines to treat swine flu?
Yes. CDC recommends the use of oseltamivir (Tamiflu) or zanamivir for
the treatment and/or prevention of infection with these swine influenza
viruses. Antiviral drugs are prescription medicines (pills, liquid or
an inhaler) that fight against the flu by keeping flu viruses from
reproducing in your body. If you get sick, antiviral drugs can make your
illness milder and make you feel better faster. They may also prevent
serious flu complications. For treatment, antiviral drugs work best if
started soon after getting sick (within 2 days of symptoms).
How long can an infected person spread swine flu to others?
People with swine influenza virus infection should be considered
potentially contagious as long as they are symptomatic and possible for
up to 7 days following illness onset. Children, especially younger
children, might potentially be contagious for longer periods.
What surfaces are most likely to be sources of contamination?
Germs can be spread when a person touches something that is
contaminated with germs and then touches his or her eyes, nose, or
mouth. Droplets from a cough or sneeze of an infected person move
through the air. Germs can be spread when a person touches respiratory
droplets from another person on a surface like a desk and then touches
their own eyes, mouth or nose before washing their hands.
How long can viruses live outside the body?
We know that some viruses and bacteria can live 2 hours or longer on
surfaces like cafeteria tables, doorknobs, and desks. Frequent
handwashing will help you reduce the chance of getting contamination
from these common surfaces.
What can I do to
protect myself from getting sick?
There is no vaccine available right now to protect against swine flu.
There are everyday actions that can help prevent the spread of germs
that cause respiratory illnesses like influenza. First and most
important: wash your hands. Try to stay in good general health. Get
plenty of sleep, be physically active, manage your stress, drink plenty
of fluids, and eat nutritious food. Try not touch surfaces that may be
contaminated with the flu virus. Avoid close contact with people who are
sick.
Take these everyday steps to protect your health:
- 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. Alcohol-based hand cleaners are also effective. - Avoid touching your eyes, nose or mouth. Germs spread this way.
- Try to avoid close contact with sick people.
- If you get sick with influenza, CDC recommends that you stay home
from work or school and limit contact with others to keep from infecting
them. - What is the best way to keep from spreading the virus
through coughing or sneezing? - If you are sick, limit your contact with other people as much as
possible. Do not go to work or school if ill. Cover your mouth and nose
with a tissue when coughing or sneezing. It may prevent those around you
from getting sick. Put your used tissue in the waste basket. Cover your
cough or sneeze if you do not have a tissue. Then, clean your hands,
and do so every time you cough or sneeze.
What is the best technique for washing my hands to avoid
getting the flu?
Washing your hands often will help protect you from germs. Wash with
soap and water. or clean with alcohol-based hand cleaner. We recommend
that when you wash your hands- with soap and warm water – that you wash
for 15 to 20 seconds. When soap and water are not available,
alcohol-based disposable hand wipes or gel sanitizers may be used. You
can find them in most supermarkets and drugstores. If using gel, rub
your hands until the gel is dry. The gel doesn’t need water to work; the
alcohol in it kills the germs on your hands.
