Key Takeaways
- Over 500 human cases of flesh-eating screwworms reported in Mexico.
- Six deaths linked to the infestations, with severe health risks.
- Animal cases exceed 36,000 since the reemergence in 2024.
- Increased surveillance and control measures recommended.
Rising Cases of Screwworm Infestation
Since the reintroduction of the flesh-eating screwworm fly in Mexico in 2024, the number of human cases has been on the rise. A report from Mexico’s Ministry of Health indicates that over 500 cases were documented in 2025 and 2026. A recent study published in the journal Emerging Infectious Diseases examined more than 200 confirmed cases from April 2025 to March 2026, revealing an alarming increase in infestations.
Impact on Human Health
Among the 200 cases analyzed, six fatalities were reported, with at least one death directly attributed to the maggots of the screwworm fly. The New World screwworm (NWS) fly, previously eradicated from Mexico and the U.S., lays eggs in the wounds and tissues of warm-blooded animals, leading to rapid maggot development that consumes living flesh. While these infestations can be devastating for livestock, they also pose serious risks to human health.
Animal Cases and Human Myiasis
Since the breach of the eradication barrier in 2022, Mexico has reported over 36,000 animal cases of NWS, with nearly 2,000 active cases as of early August. Though human infections, known as myiasis, represent a small fraction of total cases, they can result in severe and painful wounds that may lead to muscle and tissue destruction, secondary infections, and even death if not treated promptly.
Demographics of Affected Individuals
The study found that most myiasis cases occurred in older adults, with a mean age of 61. Of the confirmed cases, 72 percent involved male patients. The majority of infections were located in the lower limbs, but other areas, including the head and neck, were also affected. Many patients had underlying health conditions, such as diabetes and cancer, which may have contributed to the severity of their infections.
Need for Coordinated Response
The geographic distribution of human cases aligns closely with reported animal cases, raising questions about why men appear to be more susceptible. Factors such as occupational exposure and delayed medical attention may play a role. Researchers emphasize the importance of a coordinated response between human and animal health sectors to manage the spread of the NWS fly effectively.
Future Surveillance and Control Measures
As the NWS fly continues to spread, proactive measures including surveillance, diagnostic preparedness, and fly suppression activities are recommended. The U.S. has reported its first animal cases in Texas, but no human cases have been linked to the recent resurgence. However, travel-related cases have emerged from individuals returning from areas where NWS is endemic.
