A Rare and Startling Return
In August 2025, the United States confirmed its first human case of New World screwworm myiasis in decades, Reuters AP News. The patient, a Maryland resident returning from El Salvador, was diagnosed with a skin infestation by larvae of the Cochliomyia hominivorax fly, famously known as the screwworm.
Although primarily a livestock parasite, this case underscores a growing concern: the northward spread of screwworm infestations from Central America into the U.S., posing risks to both public health and agricultural industries.
Screwworm 101: What Makes It So Dangerous?
Screwworm larvae don’t target dead tissue, which is common among most maggots instead, they burrow into healthy, living flesh, causing severe damage and inflammation, CBS News CDC. In humans, this condition is called myiasis; without prompt removal and treatment, it can lead to secondary infections or even fatal outcomes.
Although rare in humans, livestock are highly vulnerable. Left unchecked, screwworm infestations can devastate cattle populations, potentially causing massive economic impacts.
Why Is Screwworm Resurfacing in 2025?
Previously eradicated in the U.S. by the 1960s using the sterile insect technique (SIT), the screwworm has resurged in Central America since 2023 Wikipedia and Yahoo. Movements of animals and environmental pressures have allowed the fly to drift northward, with confirmed outbreaks in Mexico, DVM 360Courthouse News.
The Maryland human case serves as a stark reminder that this parasite can traverse beyond borders, particularly affecting regions with limited veterinary and medical infrastructure.
What Are Authorities Doing Now?
Authorities have taken immediate action: The USDA has launched a renewed sterile fly production facility in Texas, mirroring earlier methods that eradicated the screwworm. ReutersPeople.com. Veterinary and agricultural agencies have also halted certain livestock imports from Mexico to prevent potential spread, Reuters, Barron’s.
Public health responses focus on swift detection and treatment of infected individuals, alongside raising awareness among healthcare providers and travellers to affected areas. Authorities are also implementing strict monitoring of livestock and agricultural products to ensure early detection of any potential outbreaks. Additionally, they are conducting public awareness campaigns to educate communities about the risks and prevention measures, aiming to minimize the spread and impact of the disease.
What You Should Know: Risks and Prevention
- Human Risk Level: Currently low, but vigilance is key, especially for travelers to outbreak zones.
- Symptoms: Look for non-healing wounds, intense pain, inflammation, or visible larvae. Medical removal and wound care are essential to the New York Post and AP News.
- Livestock Threat: An outbreak could decimate a herd of cattle and disrupt the supply chain
- Preventive Tip: Practicing good wound hygiene, covering injuries while traveling, and reporting suspicious lesions or animal cases can aid early response.
Why This Matters in 2025
There are vulnerabilities in global vector-borne disease containment, highlighted by the re-emergence of screwworm in the United States and its detection in humans. It’s a wake-up call about:
- The fragility of regional disease eradication efforts.
- Agriculture and food security face economic risks.
- The importance of coordinated surveillance and rapid response strategies.
- The fragility of regional disease eradication efforts.
- The economic risks posed to agriculture and food security.
- The importance of coordinated surveillance and rapid response strategies
These challenges underscore the need for proactive measures, including international collaboration, to strengthen disease prevention systems and protect public health and agricultural stability.
Conclusion
This 2025 human case of New World screwworm is not merely a medical oddity; it’s a crucial reminder that eradicated threats can return. Although public health officials stress that the current risk to the general population is low, livestock remains vulnerable.
Understanding screwworm’s biology, keeping informed about outbreak zones, and supporting control efforts can help ensure the U.S. does not face a full-scale resurgence of this menace. This includes monitoring livestock for signs of infection, implementing swift quarantine measures, and supporting research into effective eradication strategies. Public awareness and collaboration between farmers, veterinarians, and health authorities are essential to prevent the re-establishment of this destructive pest.