Mexico Strengthens New World Screwworm Response

Mexico is strengthening its national response to New World Screwworm by deploying a nationwide eradication campaign supported by scientific research, surveillance, early detection, and new control technologies. The effort has direct implications for Mexico’s livestock and meat industries, animal-health authorities, and US-Mexico agricultural trade, as the pest continues to pose risks to livestock production, cross-border animal movement, and market access 

The Government of Mexico, through the Ministry’s of Agriculture and Rural Development (SADER) and Science, Humanities, Technology, and Innovation (SECIHTI), established the Technical-Scientific Council of the National Strategy against New World Screwworm (GBG) to strengthen scientific, technological, and institutional capacities in support of the livestock sector.

Víctor Arrazate, Representative, SADER, highlighted that the strategy will transition from an emergency response framework based on a National Emergency Response Protocol to a nationwide campaign for the control and eradication of the New World Screwworm across all 32 states. Priority research areas include strengthening surveillance and diagnostic systems, early detection of cases, analysis of the pest’s population dynamics, the evaluation and development of new prevention, control and eradication methods, genetic and biotechnology studies, and the development of AI technologies and tools, he said.

Arrazate also highlighted the role of the National Service for Agro-Alimentary Public Health, Safety, and Quality (SENASICA) as the agency responsible for operating the national animal health campaign through ongoing epidemiological surveillance, training, case notification, animal movement controls, and the implementation of sanitary measures.

Víctor García, Deputy Director of Operations Management, SECIHTI, emphasizes that the creation of the council represents an opportunity to make the knowledge generated by Mexico’s scientific community available to the institutions responsible for the agricultural sector. “The goal is for research and scientific, humanistic, technological and innovation development to reach decision-makers directly, thereby strengthening the national strategy against the New World Screwworm,” he said.

Luis Gelasio, General Coordinator, National Animal Health Technical Advisory Council (CONASA), calls for greater collaboration and noted that CONASA has 22 committees that have been working for 34 years on animal health, animal production, and New World Screwworm issues. “There is work that has already been done, and I am pleased that we are working together with researchers, listening to all the efforts and actions underway so that we do not duplicate time and resources,” he said.

Research Targets More Precise New World Screwworm Detection 

The fight against New World Screwworm has driven the development of new scientific and technological tools in Mexico and the United States, with researchers focusing on improving early detection, surveillance, and monitoring of the pest. Researchers at the Universidad de Veracruz (UV) designed a specialized trap to capture the Cochliomyia hominivorax fly, the insect responsible for laying the eggs that give rise to this pest. The trap works by using a biological attractant that mimics the odors female flies seek when selecting sites to lay their eggs.

Once the insect enters the device, it becomes trapped and can be identified by specialists. This information makes it possible to determine whether the pest is present in a particular region and take immediate action before it can multiply. The goal is for this technology to be used in permanent surveillance and prevention campaigns, complementing the strategies implemented by SENASICA.

The university-developed tool was designed using readily available, low-cost materials, while also taking into account the need for easy installation on ranches and in livestock-producing areas. The innovation could facilitate the early detection of the fly that transmits the pest, improve monitoring programs and strengthen national efforts to protect livestock production.

Along the same lines, researchers at Colorado State University (CSU) are conducting research aimed at precisely identifying, at the molecular level, which bacterial odors attract the fly to living tissue rather than dead tissue, with the goal of developing more effective and targeted traps. The project is funded by the US Department of Agriculture (USDA) as part of a US$105 million funding package for 40 initiatives aimed at combating New World Screwworm.

Principal investigator Jessica Metcalf explains that while humans associate some of these odors with danger or decomposition, the New World Screwworm fly interprets them as signals associated with reproduction. “We use those bacterial signals to stay away from certain things, such as avoiding eating spoiled meat. Insects use them for a different reason: to them, that odor indicates an ideal place to lay eggs,” she says.

The traps in use rely primarily on the odors of decomposing meat, which mainly attract the secondary screwworm (Cochliomyia macellaria), a species that prefers dead tissue and does not pose a threat comparable to that of the New World Screwworm (Cochliomyia hominivorax). This is one of the main problems the research aims to address. When traps become filled with specimens of the secondary screwworm, they can make it more difficult to detect New World Screwworm, a species capable of infesting living tissue, says Metcalf.

Metcalf’s team will therefore seek to identify the combination of bacterial chemical compounds characteristic of living tissue with open wounds. The aim is to determine which signals allow New World Screwworm to be distinguished from its less dangerous relative and apply that knowledge to the design of more precise traps.

Illegal Cattle Imports Threaten New World Screwworm Eradication

Mexican livestock producers warn that as long as the illegal importation of cattle from Central America into Mexico continues, the risk of New World Screwworm spreading will remain, along with the possibility that the United States could once again close its border to Mexican livestock imports.

According to a report published in 2022 by InSight Crime, approximately 800,000 head of cattle enter the country illegally each year. The report identifies Lagos de Montebello, Marques de Comillas, Benemerito de las Americas, and southern Tenosique as the main entry routes.

Miguel Cerino, Head, Livestock Commission at the National Chamber of Commerce (CANACO) in Tabasco, says that the illegal trafficking of cattle from Central America into Mexico continues. He adds that cattle are transported across the border on rafts into Mexican territory and that some of the routes pass through Tenosique and Balancan, from where the animals are transported in livestock trailers.

According to Cerino, the cattle are fitted with ear tags at these locations that are made to resemble those issued through the Individual Livestock Identification System (SINIIGA), allowing them to continue toward central Mexico while being presented as animals born at Mexican production facilities. He estimates that as many as 1,000 head of cattle are currently entering the country every day.

“To this day, there is no one who can stop this type of business… the authorities are the ones allowing this business to continue,” Cerino says. He emphasizes that the situation creates unfair competition for Mexican livestock producers because intermediaries prefer undocumented animals because they are cheaper.

Victoria Dittmar, Research Project Manager, InSight Crime’s “Inside the Cattle Smuggling from Central America to Mexico” project, says that the number of cattle illegally entering Mexico may have declined following the implementation of measures to contain New World Screwworm. However, she emphasized that incentives to continue the activity remain, including the fact that these animals are cheaper than domestically sourced cattle. This particularly benefits small meat-processing companies that are unable to compete with larger operators and can purchase cattle from intermediaries who arrange for the animals to be passed off as legal using falsified documentation or no documentation at all.

Dittmar stresses that this meat is destined for the domestic market, primarily because of the breed of cattle involved and the conditions in which the animals are kept, as well as because they lack the traceability documentation required for export.