Classical Swine

Fever

Still a Threat

Classical swine fever (CSF), also known as hog

cholera, is a highly contagious viral disease of swine.

CSF was eradicated from the United States in 1978

after a 16-year effort by the industry and State and

Federal governments. Today, only 16 other countries

are free of CSF. In the spring and summer of 1997, 

outbreaks of CSF were confirmed in Haiti and the

Dominican Republic; both countries had eradicated

the disease in the early 1980's. Also in 1997, several

European countries, including the Netherlands and 

Belgium, experienced outbreaks and suffered heavy

losses. These outbreaks have animal health officials

at the U.S. Department of Agriculture (USDA) concerned that CSF could spread to U.S. swine herds.

While CSF does not cause foodborne illness in people, economic losses to pork producers would be

severe if the disease were to become established

again in this country.

Transmission

The most common method of transmission is

direct contact between healthy swine and those

infected with CSF. The disease can also be 

transmitted through contact with body secretions and

excrement from infected animals. Healthy pigs 

coming into contact with contaminated vehicles,

pens, feed, or clothing may contract the disease.

Birds, flies, and humans can physically carry the

virus from infected to healthy swine.

Swine owners can inadvertently cause infection

through feeding their herds untreated food wastes 

containing infected pork scraps.

Signs

The clinical signs of CSF vary with the severity of the

infection. There are three forms of the disease:

acute, chronic, and mild.

• The acute form of CSF is highly virulent, causing 

persistent fevers that can raise body 

temperatures as high as 107 °F. Other signs of 

the acute form include convulsions and lack of 

appetite. Affected pigs will pile or huddle up 

together. Signs of CSF may not be apparent for 

several days following infection. Death usually 

occurs within 5 to 14 days following the onset of 

illness.

• The chronic form of CSF causes similar clinical 

signs in affected swine, but the signs are less 

severe than in the acute form. Discoloration of 

the abdominal skin and red splotches around the 

ears and extremities often occur. Pigs with 

chronic CSF can live for more than 100 days 

after the onset of infection.

• The mild or clinically inapparent form of CSF 

seldom results in noticeable clinical signs.

Affected pigs suffer short periods of illness often 

followed by periods of recovery. Eventually, a 

terminal relapse occurs. The mild strain may 

cause small litter size, stillbirths, and other 

reproductive failures. High mortality during 

weaning may also indicate the presence of this 

mild strain of CSF.

How Animal Health Officials Protect U.S.

Animals

USDA's Animal and Plant Health Inspection Service

(APHIS) maintains a constant vigil against the entry 

of foreign animal diseases, such as CSF.

To ensure pigs are free of disease, swine from

countries affected by CSF can enter the United

States only after a 90-day quarantine at a high-security import center in Key West, FL.

Control

APHIS coordinates an emergency task force

made up of Federal, State, and local officials. This

task force is ready to respond immediately to any foreign disease outbreak. If an outbreak of CSF should

occur, the task force would take the following actions:

• Investigate the affected farm to determine the 

history of illness, the types and number of pigs 

affected, and to collect any other information 

relating to the illness.

• Quarantine the affected premises and the 

surrounding areas, if necessary, to restrict the 

movement of affected and exposed animals.

• Trace all movements of swine to and from the 

affected premises.

• Provide laboratory services to test affected and 

exposed animals.

• Euthanize or slaughter and dispose of all infected

and exposed animals; dispose of exposed 

materials like bedding and manure.

• Supervise cleaning and disinfection of the 

affected premises.

• Advise and assist area hog farmers if their herds 

are susceptible to the disease or located near a 

quarantined area.

Factsheet

Veterinary Services January 2002

APHIS
• Increase public awareness of the outbreak and 

control efforts through press conferences, news 

releases, and public service announcements.

• Make available an onsite public information 

specialist to answer questions and provide 

updates to the media and the public.

How Swine Owners Can Protect Their

Animals

Swine owners who suspect their pigs may have

CSF should immediately contact their local veterinarian or Federal or State animal health official. Taking

the following steps can help swine owners prevent this 

disease from becoming established in the United

States:

• Check animals at least twice a week for unusual 

signs or behaviors.

• Make sure food waste is properly heated to 

destroy pathogens.

• Isolate newly purchased hogs for at least 21 days.

• Isolate sick pigs until the cause of illness is 

determined.

• Fence property to prevent wild pigs from coming 

in contact with domestic herds.

• Practice standard biosecurity measures, such as 

cleaning and disinfecting clothing, equipment, and 

vehicles entering and leaving the farm.

Report Suspicious Cases

Veterinarians and livestock owners who suspect

an animal may have CSF or any other foreign animal 

disease should immediately contact State or Federal

animal health authorities.

For more information, contact:

USDA, APHIS, Veterinary Services

Emergency Programs

4700 River Road, Unit 41

Riverdale, MD 20737-1231

Telephone (301) 734-8073

Fax (301) 734-7817

Current information on animal diseases and 

outbreaks is also available on the Internet. Point your

Web browser to http://www.aphis.usda.gov to reach

the APHIS home page.

The U.S. Department of Agriculture (USDA) prohibits discrimination

in all its programs and activities on the basis of race, color, national

origin, sex, religion, age, disability, political beliefs, sexual orientation, or marital or family status. (Not all prohibited bases apply to

all programs.) Persons with disabilities who require alternative

means for communication of program information (Braille, large

print, audiotape, etc.) should contact USDA’s TARGET Center at

(202) 720–2600 (voice and TDD).

To file a complaint of discrimination, write USDA, Director, Office of

Civil Rights, Room 326–W, Whitten Building, 1400 Independence

Avenue, SW, Washington, DC 20250–9410 or call (202) 720–5964

(voice and TDD). USDA is an equal opportunity provider and

employer.

United States Department of Agriculture • Animal and Plant Health Inspection Service • Safeguarding American Agriculture