The US Department of Agriculture's  Animal and Plant Health Inspection Service announced on Nov. 22, 2024, that it had received an official notice from Mexican authorities about a “positive detection of New World screwworm (NWS) in Mexico.” Given the severity of the threat posed by NWS, APHIS has now suspended imports of Mexican cattle and bison until further notice.

The infestation was detected in a cow in the southern Mexican state of Chiapas. However, it may not have come as a surprise to US authorities, even though it was not made public until now. Before the elections, the Wildlife Conservation Society published a report highlighting how cattle trafficking in Central America created opportunities for the parasite to spread into Mexico. One notable sentence from their article caught our attention:

“Once the screwworm crosses the border, controlling its spread within Mexican territory will be challenging. Past experiences have demonstrated the complexity and cost of eradicating this pest; efforts in Mexico and the US in 1991 exceeded $955 million in today’s currency.”

The US cattle/beef market is right to be concerned. This pest poses a serious threat to the U.S. cattle industry, which successfully eradicated NWS almost 60 years ago, in 1966.  At this point it is not known how long the ban on imports of Mexican feeder cattle will last. What is certain is that imports of Mexican cattle — primarily going into Arizona, New Mexico and Texas — play a significant role in the US market.  Steiner estimates that imports of feeder cattle from Mexico will reach just over 1.4 million head in 2024. The USDA anticipates a slight decline in 2025, with shipments estimated at 1.2 million head.   

Considering that the US supply of feeder cattle outside feedlots at the start of the year is expected to fall below 24 million head, a complete halt to Mexican imports could reduce availability by more than 5%.  As of Nov. 1, 2024, feedlot supply was slightly higher than a year ago (+0.3%), but inventories next spring and summer — and the supply of fed cattle in the second half of the year — are now more pressing concerns. What was already a tight market has the potentially to get much tighter, and that’s even before we start talking about tariffs.