Screwworm spreads to Chihuahua, 28 of 32 states affected, losses top $2B

Chihuahua, Mexico's largest cattle exporter, confirms screwworm case as outbreak spreads to 28 states, with losses exceeding $2 billion.

The outbreak expands

Chihuahua became the 28th state to report screwworm (Cochliomyia hominivorax) after the parasite was found in the navel wound of an eight-day-old calf in Hidalgo del Parral. Authorities established a 40-kilometer surveillance perimeter with inspections and treatments. Source: excelsiormx Only four states—Baja California, Baja California Sur, Sinaloa, and Sonora—remain free. Source: excelsiormx Nationwide, there are 33,759 accumulated cases and 2,021 active cases, with Yucatán, Puebla, and Oaxaca leading active counts. Source: excelsiormx Even Mexico City has reported cases in 10 of its 16 boroughs, including three human infections. Source: excelsiormx

Economic and trade impact

The spread has hit Mexico's livestock industry hard. Private sector calculates losses over $2 billion, and the US border has been closed to Mexican cattle since November 2024. [Sources: infobae, mileniomx] Chihuahua alone accounts for nearly half of Mexico's live cattle exports to the US, making its infection particularly damaging. Source: excelsiormx The head of the CNA, Jorge Esteve Recolons, criticized the US closure as lacking scientific regionalization, noting the fly can travel via wind and wildlife. Source: infobae

Struggle to contain the pest

Mexico is struggling to produce enough sterile flies to combat the outbreak. "If it were a war, we use bullets and bombs. Our bullets and bombs are the sterile flies. We do not have statistically enough to stop the advance," said Esteve. A new plant in Chiapas aims for 100 million sterile flies per week but is currently producing about . Meanwhile, Senasica's budget has been cut by over 50% in the last decade, prompting calls for a joint public-private financing scheme.