The National Pseudorabies Eradication Program Update

Arnold C. Taft, USDA, APHIS, Veterinary Services

On January 14, 2002, the State of Iowa announced that its last pseudorabies quarantined herd had been released.  This was a significant event for the pseudorabies eradication program.  Since that time two additional swine herds have been identified as being infected with pseudorabies-one in Iowa and one in Virginia-and both have been depopulated. The Virginia herd resulted from exposure to feral swine that had escaped from a nearby hunting preserve.

Currently, 40 States plus Puerto Rico and the U.S. Virgin Islands are in Stage V (Free) status.  Six States are in Stage IV, one State in Stage III/IV, two States in Stage III and one State in stage II/III.  During FY 2002 the following States have advanced in status; New Jersey, Indiana, Texas, and Nebraska advanced to Stage IV.  Illinois advanced to Stage V.  National goals are to have all Sates in Stage IV or higher by the end of CY 2002 and to have all States in stage V (Free) status by the end of CY 2003.

An aggressive surveillance program that will identify any remaining infected herds will be necessary to complete the program.  The national goal is to survey 20 percent of the swine breeding herd each year.  This can be accomplished if 50 percent of all cull sows and boars slaughtered have a blood sample collected at that time.  Only identified sows and boars are collected at slaughter; therefore, it will be necessary to improve our national swine ID program.  With a cull rate of 40 percent of the breeding herd each year, collection of blood from one-half the animals culled would give the 20 percent surveillance annually on the entire swine breeding herd.  This rate should continue for at least 2 years after the last positive herd has been identified in order to declare the United States free of pseudorabies.

Butcher swine surveillance has become an important program to identify infection in finishing units.  With multi-site production, positive finishing units may have no connection with the breeding herds.  Collection of blood serum or meat juice from butcher swine at slaughter has proven to be more efficient than collection on the farm.  Eight major slaughter facilities in Iowa are now participating through at least the rest of FY 2002.  Results are continually being evaluated, and if necessary, collection may continue at some level beyond FY 2002.

First-point testing at markets has proven to be productive in States with large feral swine populations.  On-farm testing of domestic swine in areas with feral populations will have to continue in order to maintain the State’s status.  Surveillance in the feral population can occur at hunter kills, by trapping, or at slaughter.

A National Feral/Wild Swine Program: Why? Such a program will assure the O.I.E that measures are in place to prevent transmission of disease from the feral/wild swine to domestic swine.  A national feral/wild swine program must provide the following:

1. A national budget which provides funding for research and aid to State programs;

2. A staff to coordinate the programs;

3. Minimum guidelines for State programs; and 

4. Educational materials and training as needed.

States should have in place at least the following;

1. An advisory committee;

2. An established authority for any or all management plans;

3. Population studies;

4. Disease surveillance;

5. A separate marketing system; and

6. An educational program.

Once the country has been declared free of pseudorabies there will be no reason to have pseudorabies virus in our laboratories.  How to implement a program for removal of pseudorabies virus from the laboratories could be facilitated by a technical group of experts named to advise the Agency.