Classical swine fever (CSF), also known as hog cholera,

is a highly contagious viral disease of swine found

worldwide. CSF was eradicated from the United States in

1976 after a 15-year effort by the industry and State and

Federal governments. If a similar eradication effort had to

be mounted today, the estimated cost to the Government

would exceed $500 million.

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 illness in

people, economic losses to swine 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 CSF

virus-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 uncooked food wastes containing pork

scraps from CSF-infected hogs.

Dutch authorities spent nearly $2 billion to eradicate

CSF in 1997.

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 (41.7 °C). 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. During that

time, they can infect healthy swine.

• The mild or clinically inapparent form of CSF seldom

results in noticeable clinical signs. Affected pigs suffer

short periods of illness followed by periods of recovery.

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. Even these swine, which show no signs

of infection, are contagious.

Pigs tend to huddle together as if cold

when infected with 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 that pigs presented for importation are free of

disease, swine from countries recognized as free of CSF

can enter the United States only after a 30-day

quarantine at a high-security Federal import center.

Purplish discoloration of skin is a common sign of CSF.

Control If an Outbreak Should Strike

APHIS coordinates an emergency task force made up of

Federal, State, and local officials, 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, record the types and number of pigs

infected, and collect any other information relating to

the illness.

• Quarantine the affected premises and the surrounding

areas, if necessary, to restrict the movement of

infected and exposed animals.

• Trace all movements of swine to and from the affected

premises.

• Provide laboratory services to test infected and

exposed animals.

• Euthanize or depopulate and dispose of all infected

and exposed animals; dispose of potentially contaminated materials like bedding and manure.

• Supervise cleaning and disinfection of the affected

premises.

• Advise and assist area hog farmers if their herds are

located near a quarantined area or at risk because of

possible exposure.

• 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.

Matted eyes are a common sign of CSF.

Mesenteric lymph nodes showing

dark superficial hemorrhage.
Classical

Swine Fever:

Still a Threat

United States Department of Agriculture

Animal and Plant Health Inspection Service

Program Aid No.1662

The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color,

national origin, gender, 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, 14th and

Independence Avenue, SW, Washington, DC 20250–9410 or call

(202) 720–5964 (voice and TDD). USDA is an equal opportunity

provider and employer.

Photo Credits: The outdoor shot of euthanized pigs, the

individual swine showing discolored skin and matted eyes, and

the epiglottis image were photographed by Dr. Volker Moennig

of the Community Reference Laboratory for Classical Swine

Fever, Hanover, Germany. APHIS gratefully acknowledges his

cooperation in making these pictures available for reproduction.

The remaining images are APHIS file photographs.

Issued September 1999

This publication supersedes “Hog Cholera: Although

Eradicated, Still a Threat,” Program Aid No. 1220, issued

in 1978.

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 daily 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 suspected

outbreaks is also available on the Internet. Point your

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

APHIS home page.

Pinpoint hemorrhages on the kidneys are characteristic.

Hemorrhages commonly seen on the epiglottis of a

CSF-infected hog.

“Button” ulcers on the lining of the intestine.