LOS ANGELES, June 4 (Xinhua) -- U.S. agriculture officials have stepped up efforts to contain and eradicate the New World screwworm (NWS) after confirming the first domestic case in decades.

The U.S. Department of Agriculture (USDA) said on Wednesday that NWS larvae were found in the umbilical area of a three-week-old calf in Zavala County, Texas. No additional cases have been detected so far.

U.S. Secretary of Agriculture Brooke Rollins said on Thursday that federal and state authorities are fully implementing an emergency response plan to prevent further spread within the country. Measures include a 20-km control zone around the detection site, quarantines, livestock movement restrictions and intensified surveillance.

Authorities are also expanding the targeted release of sterile NWS flies, increasing trapping for NWS flies along the border, and enhancing wildlife monitoring. Rollins said approximately 8 million sterile flies are being released weekly through both aerial and ground-based operations.

NWS is a serious parasitic pest that affects livestock, pets, wildlife and, in rare cases, people. Its larvae burrow into the flesh of living animals through wounds and feed on living tissue, causing severe damage to livestock.

Although eradicated from the United States decades ago, the pest remains present in parts of South America, where infections in animals and humans continue to occur. In recent years, however, the pest has spread northward through Central America and Mexico, according to the USDA.