A new case of New World screwworm has been confirmed in a horse in Grant County, south-western New Mexico, near the border with Mexico. The US Department of Agriculture confirmed it on Thursday — the state's second case since the parasite returned to the United States this summer, and one that arrives days before a major border port is scheduled to reopen to Mexican cattle.

New Mexico's first case, in a dog, was confirmed on 7 June. Weeks passed without another detection, and the state's screwworm-infested zone was released on 30 August after officials judged that federal requirements for lifting restrictions had been met; surveillance, trapping and monitoring continued afterwards.

The timing matters for the cattle trade. Earlier on Thursday, Agriculture Secretary Brooke Rollins announced at a news conference in Santa Teresa that the USDA was preparing to reopen the Santa Teresa, New Mexico, port of entry to livestock from Mexico on 24 September. Bloomberg reported that the port is roughly 150 miles from the Grant County case, and according to the New Mexico Department of Agriculture the horse's infection had not yet been confirmed when the announcement was made.

Santa Teresa would be the next major port to reopen under the USDA's phased restoration of livestock trade with Mexico: the Douglas, Arizona, port reopened to cattle imports on 24 August, and the agency had said Santa Teresa and Columbus, New Mexico, would be considered next, depending on conditions and on Mexico's progress under a joint action plan to control the parasite. Every animal entering through a reopened port undergoes a full USDA inspection for screwworm, and the agency has stressed that the schedule is flexible and ports can be paused if risk rises in northern Mexico.

The USDA has tracked 50 confirmed New World screwworm cases in the United States since the first domestic detection on 3 June; as of Thursday three remained active, according to USDA data cited by The Hill. Four cases were reported in August, all in Texas, and September has so far brought two — one in Texas and the new one in New Mexico. The latest detection may add another consideration as federal and state officials weigh conditions ahead of the 24 September reopening.

Source: AGDAILY