Parasitic New World Screwworm Cases Reported Near Texas-Mexico Border
Cases of the New World screwworm, a parasitic fly, have been reported in Mexican states bordering Texas. U.S. officials have closed southern ports to livestock trade in response. The fly was eradicated from the United States in 1966 but has been moving northward from South America.
bbc.co.ukThe U.S. More recent cases among cattle were identified in Tamaulipas, a state bordering Texas, according to the latest USDA data as of April 21. The USDA stated there is no current risk to livestock, pets or people in the United States. American officials have closed southern ports of entry to livestock trade.
Centers for Disease Control and Prevention. The eggs hatch into maggots that consume live tissue. After several days, larvae drop to the ground, burrow into soil and emerge as adult flies.
The USDA declared the United States free of indigenous screwworms in 1966, using a technique involving the sterilization of male flies. In subsequent decades, the parasitic fly has returned northward from endemic regions in South America, causing outbreaks in Central America and Mexico.
Mexico supplies cattle to the United States. A study published in Nature in July stated that climate change contributes to the re-emergence of the fly due to hotter temperatures and changing weather patterns. These conditions could favor the spread of the fly in Texas, which has the nation's largest cattle industry, and other southern U.S. regions.
Isolated cases of human infections have occurred in individuals returning to the United States from international travel. A small outbreak was reported in the Florida Keys in 2017.
