The reemergence of the New World screwworm and its potential distribution in North America.
Abstract: The reemergence of the New World screwworm (Cochliomyia hominivorax) poses a significant threat to animal and public health with minimal regulatory oversight. This study analyzes the potential distribution and reemergence of this pest, which is endemic to South America but was previously eradicated in North America. We first developed bioclimatic suitability models, and then incorporated these findings along with reemergence records and inspection point data to simulate possible dispersal routes into Mexico and the United States. Our results document the historical distribution of C. hominivorax across the Americas and recent reemergence events in Panama (2023) and Mexico (2024-2025). Findings indicate high invasion potential from Central America, with significant risk along Mexico's Pacific and Atlantic coasts and the Yucatan Peninsula. In the United States, Texas and Florida face the highest risk. Regions with high livestock density in both countries demonstrate considerable climatic suitability for the pest. Our simulations identify Chiapas, Campeche, Tabasco, and Veracruz as critical northern dispersal points. The invadable areas contain substantial populations of domestic hosts, primarily cattle and horses. These findings will enable governmental authorities to develop comprehensive prevention and control strategies to address this emerging threat.
© 2025. The Author(s).
Publication Date: 2025-07-03 PubMed ID: 40610581PubMed Central: PMC12229696DOI: 10.1038/s41598-025-04804-9Google Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
Summary
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Overview
- This study investigates the resurgence of the New World screwworm (Cochliomyia hominivorax), a pest once eradicated in North America but now reemerging and threatening animal and public health.
- The research models its potential distribution and dispersal routes to inform prevention and control efforts in Mexico and the United States.
Background
- New World Screwworm (Cochliomyia hominivorax): A parasitic fly native to South America that infests wounds in warm-blooded animals, causing severe tissue damage and economic losses in livestock.
- Eradication History: Previously eradicated from North America through extensive programs, but recent reports indicate its return in Central America and Mexico.
- Health and Economic Impact: Poses significant risks to animal welfare, public health, and livestock industries if it spreads unchecked.
Research Objectives
- Assess the current and potential geographic distribution of the New World screwworm in North America.
- Identify areas at greatest risk of invasion and reemergence based on climate, host availability, and dispersal pathways.
- Provide actionable insights to guide surveillance, prevention, and mitigation strategies by authorities.
Methodology
- Bioclimatic Suitability Modeling: Developed models to predict regions where climate conditions would support the survival and reproduction of the screwworm.
- Incorporation of Reemergence Data: Integrated recent confirmed sightings and collections of the pest in Panama (2023) and Mexico (2024-2025).
- Inspection Point Data: Used pest interception records at border inspection points to simulate and identify potential dispersal routes.
- Simulation of Dispersal Routes: Modeled possible pathways the screwworm could follow entering and spreading through Mexico and the United States.
Key Findings
- Historical and Recent Distribution: The screwworm’s native range includes South America; recent outbreaks in Panama and Mexico highlight its northward movement.
- High-Risk Regions in Mexico: Pacific and Atlantic coastal areas, as well as the Yucatan Peninsula, demonstrated high climatic suitability and likely serve as entry points.
- Critical Northern Dispersal Points: States such as Chiapas, Campeche, Tabasco, and Veracruz identified as important gateways for northward spread.
- Risk in the United States: Texas and Florida are the most vulnerable due to climate suitability and presence of abundant livestock hosts.
- Livestock Density Correlation: The invadable regions overlap with areas having significant populations of cattle and horses, which serve as primary hosts.
Implications and Recommendations
- Threat Recognition: The reemergence signals an urgent need for heightened awareness and regulatory attention.
- Prevention Strategies: Authorities should prioritize surveillance in identified high-risk zones and border inspection points to detect and respond rapidly.
- Control Measures: Development and deployment of targeted pest management, including sterile insect techniques and animal wound management, especially in livestock dense areas.
- Cross-Border Collaboration: Essential to coordinate efforts between South, Central, and North American countries to monitor pest movement and implement synchronized control.
- Research Utility: The models and simulations provide a strategic framework to allocate resources effectively and limit the screwworm’s spread before significant damage occurs.
Cite This Article
APA
Valdez-Espinoza UM, Fadda LA, Marques R, Osorio-Olvera L, Jiménez-García D, Lira-Noriega A.
(2025).
The reemergence of the New World screwworm and its potential distribution in North America.
Sci Rep, 15(1), 23819.
https://doi.org/10.1038/s41598-025-04804-9 Publication
Researcher Affiliations
- Red de Estudios Moleculares Avanzados, Instituto de Ecología A. C., Carretera antigua a Coatepec 351, El Haya, Xalapa, C. P. 91073, Veracruz, México.
- Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias, Centro Nacional de Investigación Disciplinaria en Salud Animal e Inocuidad, Carretera Federal Cuernavaca - Cuautla No. 8534, Colonia Progreso, Jiutepec, C.P. 62574, Morelos, México.
- Red de Estudios Moleculares Avanzados, Instituto de Ecología A. C., Carretera antigua a Coatepec 351, El Haya, Xalapa, C. P. 91073, Veracruz, México.
- Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias, Centro de Investigación Regional Golfo Centro, Campo Experimental Cotaxtla, Km 34.5, Carretera Veracruz-Córdoba, Veracruz, C.P. 94270, México.
- Laboratorio de Biodiversidad, Centro de Agroecología y Ambiente, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Edificio Val. 1, Km 1.7 carretera a San Baltazar Tetela, San Pedro Zacachimalpa, Puebla, C.P. 72960, Puebla, México.
- Laboratorio de Ecoinformática de la Biodiversidad, Departamento de Ecología de la Biodiversidad, Instituto de Ecología, Unidad Mérida, Universidad Nacional Autónoma de México, 04510 Mérida, Yucatán, México.
- Laboratorio Nacional SECIHTI de Biología del Cambio Climático, Ciudad de México, México.
- Laboratorio de Biodiversidad, Centro de Agroecología y Ambiente, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Edificio Val. 1, Km 1.7 carretera a San Baltazar Tetela, San Pedro Zacachimalpa, Puebla, C.P. 72960, Puebla, México. daniel.jimenez@correo.buap.mx.
- Laboratorio Nacional SECIHTI de Biología del Cambio Climático, Ciudad de México, México. daniel.jimenez@correo.buap.mx.
- Secihti Research Fellow, Red de Estudios Moleculares Avanzados, Instituto de Ecología A. C., Carretera antigua a Coatepec 351, El Haya, Xalapa, C. P. 91073, Veracruz, México. aliranoriega@gmail.com.
MeSH Terms
- Animals
- North America / epidemiology
- Cattle
- Mexico
- United States
- Diptera
Conflict of Interest Statement
Declarations. Competing interests: The authors declare no competing interests. Additional information: All supplementary information is available in the Zenodo repository ( https://doi.org/10.5281/zenodo.15465751 ).
References
This article includes 96 references
- Gilbert M. Global distribution data for cattle, buffaloes, horses, sheep, goats, pigs, chickens and ducks in 2010.. 2018.
- United State od Departament of Agriculture (USDA). . (2024). https://www.ers.usda.gov/data-products/livestock-and-meat-international-trade-data
- Magaña M. Indicadores de competitividad de La carne Bovina de México En El Mercado mundial.. 2020.
- Servicio de información agroalimentaria y Pesquera (SIAP). . (2024). https://www.gob.mx/siap/acciones-y-programas/panorama-agroalimentario-258035
- Gonzales K, Prado F, García A. Producción y comercio de la carne en el mundo y en México.. 23, 136–155 (2023).
- Rhonda S. Exportaciones de Ganado En pie de México Hacia Los Estados unidos: ¿de Dónde viene El Ganado y Hacia Dónde va?. 212–219 (2004).
- Rinconada Carbajal F, Serna Hinojosa JA, Valdez ramírez RI. Competitividad de La carne de res Fresca Mexicana En El Mercado estadounidense, 1967–2020.. 129–148 (2023).
- Servicio de información agroalimentaria y Pesquera (SIAP). . (2024). https://nube.siap.gob.mx/exportacion_ganado/
- Bowman DD. Successful and currently ongoing parasite eradication programs.. 2006.
- Bushland RC, Hopkins DE. Experiments with Screw-Worm flies sterilized by X-Rays1.. 1951.
- Knipling EF. Sterile insect technique as a screwworm control measure: the concept and its development.. 4–7, (985).
- Wainwright SH. Reemerging/Notifiable Diseases to Watch.. vol. 40 Preprint (2024).
- Coquerel C. Note Sur des larves appartenant a Une espece Nouvelle de diptere ().. 171–176 (1858).
- Quiroz H. Gusano Barrenador: biología Del Gusano Barrenador Del Ganado.. 4–11 (2003).
- World Organisation of Animal Health (WOAH). Terrestrial Manual Online Access. Chapter 3.1.14 New World screwworm (Cochliomyia hominivorax) and Old World Screwworm (Chrysomya Bezziana).. 2025.
- Mastrangelo, T. & Welch, J. B. An overview of the components of AW-IPM campaigns against the New World screwworm. vol. 3 Preprint at (2012). 10.3390/insects3040930
- Fresia, P. et al. Historical perspective and new avenues to control the myiasis-causing fly in Uruguay. , (2021).
- Thomas, D. B. & Mangan, R. L. Oviposition and Wound-Visiting behavior of the screwworm fly, (Diptera: Calliphoridae). , (1989).
- Rahn, J. J. & Barger, G. L. Weather conditions and screwworm activity. , 197–211 (1973).
- Hightower, B. G., Adams, A. L. & Alley, D. A. Dispersal of released irradiated Laboratory-Reared Screw-Worm Flies1. , 373–374 (1965).
- Mayer, D. G. & Atzeni, M. G. Estimation of dispersal distances for (Diptera: Calliphoridae). , (1993).
- Quiroz, H. Gusano Barrenador: historia de La Campaña de erradicación contra El Gusano Barrenador Del Ganado. , 4–11 (2003).
- Krafsur, E. S., Whitten, C. J. & Novy, J. E. Screwworm eradication in North and Central America. vol. 3 Preprint at (1987). 10.1016/0169-4758(87)90196-7
- (Comisión México-Americana para la Erradicación del Gusano Barrenador del Ganado) COMEXA. Gusano Barrenador: XXX aniversario de La planta productora de de Moscas estériles Del Gusano Barrenador Del Ganado. , 4–11 (2003).
- Servicio Nacional de Sanidad, Inocuidad y Calidad Agroalimentaria (SENASICA). Análisis Del Impacto Potencial Del Gusano Barrenador En México. (2019).
- Vargas-Terán, M. The new world screwworm in Mexico and central America. 28–35 (1991).
- Grisi, L. et al. Reassessment of the potential economic impact of cattle parasites in Brazil. , (2014).
- Vo, T. Economic impact of eradicating the New World screwworm () from Jamaica. in 113–116Penang, Malaysia, (2000).
- Dupuis, J. R. et al. Molecular characterization of the 2016 new world screwworm (Diptera: Calliphoridae) outbreak in the Florida keys. , (2018).
- Skoda, S. R., Phillips, P. L., Welch, J. B. & Screwworm (Diptera: Calliphoridae) in the United States: Response to and elimination of the 2016–2017 outbreak in Florida. 55 Preprint at (2018). 10.1093/jme/tjy049
- Venegas-Montero, D. P. et al. Case report: Re-emergence of in Costa rica: report of a human myiasis case 23 years after elimination. , 1020–1023 (2024).n
- Comisión Panamá – Estados Unidos para la Erradicación y Prevención del Gusano Barrenador del Ganado. Comisión Panamá – Estados Unidos para la Erradicación y Prevención del Gusano Barrenador del Ganado (COPEG). (2025). https://www.copeg.org/
- World Animal Health Information System (WAHIS). (2025). https://wahis.woah.org/#/event-management
- Animal and Plant Health Inspection Service (APHIS). . (2024). https://www.aphis.usda.gov/live-animal-import/cattle-bison-germplasm/mexico
- Herrera, D. 15 mil cabezas de ganado de Tamaulipas acorraladas por gusano barrenador. (2024). https://daisyherrera.com/15-mil-cabezas-de-ganado-de-tamaulipas-acorraladas-por-gusano-barrenador/?fbclid=IwZXh0bgNhZW0CMTEAAR39GAMvaz7XEs8j9s4rrpXCV0xma0e0dTJxgmYYoItiJwS3atzDg4tOs6Q_aem_t_A7pq1qUvDNC8whlT50jA
- Barragán, A. El Regreso Del Gusano Barrenador Pone En Jaque al sector Ganadero mexicano: no Podemos Vender Nuestros Becerros. (2024). https://elpais.com/mexico/2024-12-16/el-regreso-del-gusano-barrenador-pone-en-jaque-al-sector-ganadero-mexicano-no-podemos-vender-nuestros-becerros.html
- Chamberlain, S. Package ‘spocc’ - Interface to Species Occurrence Data Sources. Preprint at (2018).
- Global Biodiversity Information Facility (GBIF). . (2024). 10.15468/dl.d4r7tw
- Osorio-Olvera, L. et al. ntbox: an R package with graphical user interface for modelling and evaluating multidimensional ecological niches. , (2020).
- Aiello-Lammens, M. E. et al. SpThin: an R package for Spatial thinning of species occurrence records for use in ecological niche models. , (2015).
- Soberon, J. & Peterson, A. T. Interpretation of models of fundamental ecological niches and species’ distributional areas. , (2005).
- Barve, N. et al. The crucial role of the accessible area in ecological niche modeling and species distribution modeling. , (2011).
- Machado-Stredel, F., Cobos, M. E. & Peterson, A. T. A simulation-based method for selecting calibration areas for ecological niche models and species distribution models. , (2021).
- Fick, S. E. & Hijmans, R. J. WorldClim 2: new 1-km Spatial resolution climate surfaces for global land areas. , 4302–4315 (2017).
- Booth, T. H. Checking bioclimatic variables that combine temperature and precipitation data before their use in species distribution models. , 1506–1514 (2022).
- Rojas-Soto, O. et al. Calibration areas in ecological niche and species distribution modelling: unravelling approaches and concepts. , (2024).
- Jiménez, L. & Soberón, J. Estimating the fundamental niche: accounting for the uneven availability of existing climates in the calibration area. , (2022).
- Osorio-Olvera, L., Soberón, J. & Falconi, M. On population abundance and niche structure. , 1415–1425 (2019).
- Osorio-Olvera, L., Yañez-Arenas, C., Martínez-Meyer, E. & Peterson, A. T. Relationships between population densities and niche-centroid distances in North American birds. vol. 23 Preprint at (2020). 10.1111/ele.13453
- Ochoa-Zavala, M. et al. Reduction of genetic variation when Far from the niche centroid: prediction for Mangrove species. , (2021).
- Nava-Bolaños, A. et al. Critical areas for pollinator conservation in mexico: A cross-border priority. , (2023).
- Soberón, J. & Osorio-Olvera, L. A dynamic theory of the area of distribution. , (2023).
- Osorio-Olvera, L. & Soberón, J. Species Distribution Models as a Function of Biotic, Abiotic and Movement Factors (BAM). (2024). https://luismurao.github.io/bamm
- Gray, L. Mathematician looks at wolfram’ s new kind of science. . , 200–211 (2002).
- Nuñez-Penichet, C., Soberón, J. & Osorio-Olvera, L. The dispersal patterns of a migratory insect are driven by biotic interactions. , (2023).
- Nuñez-Penichet, C. et al. Geographic potential of the world’s largest hornet, Vespa mandarinia Smith (Hymenoptera: Vespidae), worldwide and particularly in North America. 9, (2021).
- De Wysiecki, A. M., Cortés, F., Jaureguizar, A. J. & Barnett, A. Potential global distribution of a temperate marine coastal predator: the role of barriers and dispersal corridors on subpopulation connectivity. , (2022).
- Pimentel, D., Zuniga, R. & Morrison, D. Update on the environmental and economic costs associated with alien-invasive species in the united States. , (2005).
- Gutierrez, A. P. & Ponti, L. Eradication of invasive species: why the biology matters. , (2013).
- McGarry, J. W. Tropical myiases: neglected and well travelled. , (2014).
- Muchiut, S., Miró, M. V., Anziani, O., Nava, S. & Lifschitz, A. Failure of doramectin and Ivermectin in preventing myiasis in a subtropical region: A pharmacokinetic-pharmacodynamic study. , 110384 (2025).n
- Subedi, B., Poudel, A. & Aryal, S. The impact of climate change on insect pest biology and ecology: implications for pest management strategies, crop production, and food security. , (2023).
- Hulme, P. E. Invasive species challenge the global response to emerging diseases. , (2014).
- Gutierrez, A. P. & Ponti, L. The new world screwworm: prospective distribution and role of weather in eradication. , (2014).
- Gutierrez, A. P., Ponti, L. & Arias, P. A. Deconstructing the eradication of new world screwworm in North america: retrospective analysis and climate warming effects. , (2019).
- Baumhover, A. H. A Personal Account of programs to eradicate the screwworm, , in the United States and Mexico with special emphasis on the Florida program. in (1997).
- Lindquist, A. W. & Barrett, W. L. Overwintering of at uvalde, Texas. , (1945).
- Adams, T. S. The reproductive physiology of the screwworm, (Diptera: Calliphoridae) II. Effect of constant temperatures on oogenesis. , 484–487 (1979).n
- Forero Becerra, E., Cortes, J. A. & Villamil, L. C. Ecologia y epidemiologia Del Gusano Barrenador Del Ganado (Coquerel, 1858). (2007).
- Fresia, P., Azeredo-Espin, A. M. L. & Lyra, M. L. The phylogeographic history of the new world screwworm fly, inferred by approximate bayesian computation analysis. , (2013).
- Mulieri, P. R. & Patitucci, L. D. Using ecological niche models to describe the geographical distribution of the myiasis-causing (Diptera: Calliphoridae) in Southern South America. , (2019).
- Anziani, O. S. & Volpogni, M. M. Incidence of bovine myiasis () in the central area of Argentina. in , (1996).
- Costa-Júnior, L. M. et al. A review on the occurrence of (Diptera: Calliphoridae) in Brazil. , (2019).
- Phillips, P. L., Welch, J. B. & Kramer, M. Seasonal and Spatial distributions of adult screwworms (Diptera: Calliphoridae) in the Panama Canal area, Republic of Panama. , 121–129 (2004).n
- Brenner, R. J. Distribution of screwworms (Diptera: Calliphoridae) relative to land use and topography in the humid tropics of Southern Mexico. , (1985).
- Lassala, A., Hernández-Cerón, J., Pedernera, M., González-Padilla, E. & Gutiérrez, C. G. Cow-calf management practices in mexico: reproduction and breeding. , (2020).
- James, M. T. . (U.S. Dept. of Agriculture, Washington, D.C.:, (1947). 10.5962/bhl.title.65688
- Lindquist, D. A., Abusowa, M. & Hall, M. J. R. The new world screwworm fly in libya: a review of its introduction and eradication. , (1992).
- Fresia, P. et al. Applying Spatial analysis of genetic and environmental data to predict connection corridors to the new world screwworm populations in South America. , (2014).
- Tietjen, M., Pfeiffer, V. & Poh, K. C. Insights into the genetic landscape and presence of in the Caribbean. , (2023).
- Tietjen, M. et al. Geographic population genetic structure of the new world screwworm, (Diptera: Calliphoridae), Using SNPs. , (2022).
- Knipling, E. . (1979).
- Knipling, E. F. Entomology and the management of man’s environment. , (1972).
- United States Departament of Agriculture (USDA). . (2025). https://www.usda.gov/about-usda/news/press-releases/2025/02/01/cattle-and-bison-imports-mexico-resume-under-new-protocol
- Animal and Plant Health Inspection Service- Servicio Nacional de Sanidad, Inocuidad y Calidad Agroalimentaria (APHIS-SENASICA). . (2025). https://www.aphis.usda.gov/sites/default/files/aphis-senasica-nws-protocol-import-ruminants.pdf?utm_medium=email&utm_source=govdelivery
- Fadda, L. A., Osorio-Olvera, L., Ibarra-Juárez, L. A., Soberón, J. & Lira-Noriega, A. Predicting the dispersal and invasion dynamics of ambrosia beetles through demographic reconstruction and process-explicit modeling. , 7561 (2024).n
- Hightower, B. G., Davis, R. B., Baumhover, A. H. & Graham, O. H. Seasonal abundance of the Screw-Worm in Northern Mexico1. , (1966).
- Coronado, A. & Kowalski, A. Current status of the new world screwworm in Venezuela. , (2009).
- Van De Vuurst, P. & Escobar, L. E. Climate change and infectious disease: a review of evidence and research trends. , (2023).
- Van de Vuurst, P., Qiao, H., Soler-Tovar, D. & Escobar, L. E. Climate change linked to vampire Bat expansion and rabies virus spillover. 10.1111/ecog.06714 (2023).n
- Ogden, N. H. & Lindsay, L. R. Effects of climate and climate change on vectors and Vector-Borne diseases: ticks are different. , (2016).
- Altizer, S., Ostfeld, R. S., Johnson, P. T. J., Kutz, S. & Harvell, C. D. Climate change and infectious diseases: from evidence to a predictive framework. , (2013).
- United States Departament of Agriculture (USDA). . (2024). https://www.nass.usda.gov/Publications/AgCensus/2022/index.php
- Cunningham, E. P. et al. Le programme d’éradication de La Lucilie bouchère d’afrique du Nord. , (1992).
- Reck, J. et al. Does Rhipicephalus microplus tick infestation increase the risk for myiasis caused by in cattle? , (2014).
- Dicko, A. H. et al. Using species distribution models to optimize vector control in the framework of the Tsetse eradication campaign in Senegal. . , 10149–10154 (2014).n
Citations
This article has been cited 3 times.- Casanova-Hernández D, Pinacho-Pinacho CD, Calixto-Rojas M, Rubio-Godoy M, García-Saldaña EA, Velázquez-Velázquez E, Zamora-Briseño JA. New tools to uncover old tricks: an update on the knowledge on the most successful invasive freshwater helminth, Schyzocotyle acheilognathi.. Parasitol Res 2025 Dec 8;124(12):153.
- Lowman AV, Arp AP, Sagel A, Patil AA, Quintero G, Vasquez M, Arias AD, Martinez A, Scott MJ. Improving the sex-specificity of a conditional female lethal system for genetic biocontrol of the New World screwworm, Cochliomyia hominivorax.. Sci Rep 2025 Nov 18;15(1):40516.
- Blănaru AM, Toderan AR, Oancea A, Hristea A. Furuncular cutaneous myiasis after travel in South America: case report and epidemiologic, diagnostic and management considerations.. Trop Dis Travel Med Vaccines 2025 Oct 16;11(1):36.
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