USDA - APHIS - International Safeguarding

By 1966 the last self-sustaining screwworm fly population was eliminated in the U.S. Southwest, and the fertile fly population was greatly reduced in the northern part of Mexico. However, annual northward migrations of Screwworm from central and southern Mexico continued to cause losses.

As a result of requests by livestock producers in Mexico and the United States, a study was conducted in the mid-1960’s to determine the feasibility of eradicating Screwworm from Mexico. The study showed that, using an eradication program similar to those in the United States, Screwworms could be eliminated from Mexico.

Livestock producers from both countries joined together to request of their respective governments that an eradication program be established in Mexico. As a result, the Secretaries of Agriculture of the two countries signed an international agreement of August 28, 1972, forming the Joint Mexico-U.S. Commission for the Eradication of Screwworms. The original goal of the Commission was to eradicate Screwworms north and west of the Isthmus of Tehuantepec in southern Mexico and to establish a new barrier zone there to prevent re-infestation to the north.

A sterile fly production plant was constructed near Tuxtla Gutierrez in the sate of Chiapas where plans called for the maintenance of the permanent barrier. This plant began producing sterile flies toward the end of 1976 and has continued producing flies without interruption up to the present.

Current sterile fly production at the Tuxtla plant is less than 100 million per week with a total Commission work force of about 400 employees. At the height of the program in Mexico in 1983-1984 the plant produced more than 500 million sterile flies per week with a total Tuxtla work force of 1,200 employees. During this period, the total number of Commission employees including the Tuxtla plant, five regional offices, quarantine stations, and Mexico City headquarters was about 2,600.

By the end of 1984, the original goal of the program was achieved and all of Mexico was eradicated down to the Isthmus of Tehuantepec. At this same time, a study was undertaken to determine the feasibility of extending the eradication program to include the rest of Mexico (the Yucatan Peninsula), and all of the countries of Central America and Panama, with the objective of establishing the sterile fly barrier at the Isthmus of Panama.

In 1986, the agreement between the United States and Mexico was amended to extend the program to the rest of Mexico and to authorize the cooperation with the other countries of Central America and Panama to eradicate Screwworms from those countries. In December 1986, the Commission signed agreement with the Government of Guatemala to extend the screwworm eradication to Guatemala. The same type of agreement was signed with the government of Belize in August 1988.

The screwworm eradication programs in the other countries of Central America- Honduras, El Salvador, Nicaragua, Costa Rica – and Panama were based on agreements between the Government of the United States and the respective countries. Agreements were signed with Honduras, El Salvador, and Nicaragua in 1991, with Costa Rican in 1993, and with Panama in 1994.