Standardization of the equine infectious anemia immunodiffusion test and its application to the control of the disease in the United States.

The research paper discusses the implementation and impact of the equine infectious anemia immunodiffusion test by the US Department of Agriculture (USDA) to control the spread of the disease among horses in the United States during the 1970s.

Introduction and Context

• In 1972, the USDA established certain controls on the transport of horses based on their reaction to the equine infectious anemia immunodiffusion test. This decision was taken due to the infectious nature of the disease and the need to prevent its spread among equine populations.
• The regulations required that horses should have a negative equine infectious anemia immunodiffusion test result before they could be moved, with similar policies being adopted by 42 states.

Implementation and Procedure

• In order to standardize the immunodiffusion testing process, the USDA in 1972 decided that such tests should only be carried out in approved laboratories. The criteria for a lab to be approved included having trained personnel proficient in performing the immunodiffusion test procedure, adherence to the standard protocol, the use of licensed reagents, passing proficiency tests, and the reporting of results to federal or state animal health officials.
• The number of approved labs reached 160 by June 1983.

Testing and Disease Control

• As a result of these implemented measures, the number of immunodiffusion tests conducted across the United States increased significantly, from 82,777 in 1972 to 793,536 in 1977, remaining around that level subsequently.

Impact of the Standardization Programme

• The standardization program brought significant improvements to the disease control measures. The percentage of positive samples of equine infectious anemia decreased from 3.9 percent in 1972 to 0.6 percent in 1982, highlighting the effectiveness of the controls put in place by the USDA.
• Furthermore, due to the laboratory standardization program, the reproducibility of the immunodiffusion test results was found to be excellent, which implies that the results were accurate and dependable, thus ensuring the effective control of the disease.