FLU CAN SPREAD BETWEEN PIGS AND PEOPLE

Information for people exposed to pigs, including people who enter the swine barns at agricultural fairs or people who raise pigs for show or farming

PIG TO PERSON

FLU CAN SPREAD THROUGH DIRECT CONTACT

Infected pig

Flu virus

A person becomes infected 

when virus enters through 

the eyes, nose or mouth

Infected pig

A person becomes infected 

when virus enters through 

the eyes, nose or mouth

Coughing (Barking) or Sneezing

PERSON TO PIG

An infected person 

touches eyes, nose

or mouth

A pig becomes infected when virus 

enters through the eyes, 

nose or mouth

An infected person 

touches eyes, nose

or mouth

A pig becomes infected when 

virus enters through the eyes, 

nose or mouth

Coughing or Sneezing

www.cdc.gov/flu/swineflu/index.htm

CS278012

FLU CAN SPREAD THROUGH SURFACE CONTACT

FLU CAN SPREAD THROUGH THE AIR (IN DROPLETS OR DUST)
When influenza (flu) viruses that normally circulate in pigs are 

detected in people, they are called “variant” flu viruses and 

are designated with the letter “v,” such as H1N1v and H3N2v. 

Variant flu virus infections in people occur rarely. This fact 

sheet has information about flu viruses in pigs and variant flu 

viruses in people.

FLU VIRUSES IN PIGS 

Pigs can be infected with their own flu viruses that are usually different from 

human flu viruses. Flu viruses can spread from pigs to people, and also from 

people to pigs. Pigs also are susceptible to infection with flu viruses from other 

animal species, such as birds. 

VARIANT FLU VIRUSES IN PEOPLE

Most reported variant flu virus infections in people have occurred following 

exposure to infected pigs or their virus contaminated environments, 

particularly in association with large agricultural fairs. U.S. agricultural fairs 

take place every year, primarily during the summer months and into early fall. 

Many fairs have swine exhibitions, where pigs from different farms come in 

close contact with each other and with people. 

Spread of flu viruses between pigs and people is thought to occur in one of 

three ways:

• The main way is when an infected pig (or person) coughs or sneezes, and 

droplets containing virus spread through the air. If these droplets land in the 

nose or mouth, or are inhaled by another person or pig, infection can result.

• There also is evidence that variant flu viruses can spread by touching 

something that has virus on it and then touching the eyes, nose or mouth.

• A third way to possibly get infected is to inhale small particles in the air that 

contain variant flu virus. 

Most variant flu virus infections have resulted in mild illness in people, but 

severe illness, including illness resulting in hospitalization and death can and 

has occurred. 

Similar to seasonal flu, some people are at high risk of developing serious 

illness from variant flu virus infections. This includes children younger than 

5 years old, people 65 years of age and older, pregnant women, and people 

with certain underlying health conditions (like asthma and other lung disease, 

diabetes, heart disease, weakened immune systems, and neurological or 

neurodevelopmental conditions). 

Variant flu viruses have not been shown to be transmissible through eating 

pork (pig meat) and other pork products derived from pigs.

PRECAUTIONS TO PREVENT SPREAD 

OF FLU BETWEEN PIGS AND PEOPLE

• CDC and USDA recommend that people at high risk for serious flu 

complications avoid pigs and swine barns at fairs. 

• Do not take food or drink into pig areas; don’t eat, drink or put 

anything in your mouth in pig areas.

• Don’t take toys, pacifiers, cups, baby bottles, strollers, or similar 

items into pig areas.

• Avoid close contact with pigs that look or act ill.

• Wash your hands often with soap and running water before and 

after exposure to pigs or their environments. If soap and water are 

not available, use an alcohol-based hand rub.

• Watch your pig (if you have one) for illness. Call a veterinarian if 

you suspect illness in your pig.

• If you must work around sick people or pigs, use appropriate 

personal protective equipment such as gloves and a face mask or 

respirator.

• Avoid contact with pigs if you have flu symptoms.

More information is available at www.cdc.gov/flu/swineflu/index.htm