Swine Flu

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 re-assort 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 4 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.

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.

What are the symptoms of swine flu in humans?

The symptoms of swine flu in people

are expected to be similar to the symptoms of regular human seasonal influenza and

include fever, lethargy, lack of appetite and coughing.

Some people with swine flu also have reported

runny nose, sore throat, nausea, vomiting and diarrhea.

Can people catch swine flu from eating pork?

No.

Swine influenza viruses are not transmitted by food.

You can not get swine influenza from eating pork or pork products.

Eating properly handled and cooked pork and pork products is safe.

Cooking pork to an internal temperature of 160°F

kills the swine flu virus as it does other bacteria and viruses.

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.

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.

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.

What medications are available to treat swine flu infections in humans?

There are 4 different antiviral drugs

that are licensed for use in the US for the treatment of influenza:

amantadine, rimantadine, oseltamivir and zanamivir.

While most swine influenza viruses have been susceptible to all 4 drugs,

the most recent H1N1 influenza viruses isolated from humans are resistant to amantadine and rimantadine.