What's happened
On August 4, 2025, the CDC confirmed the first US human case of New World screwworm in Maryland, involving a patient recently returned from El Salvador. The flesh-eating parasite, primarily affecting livestock, has been spreading northward through Central America and Mexico since 2023. The US is responding with plans for a sterile fly facility in Texas to prevent reintroduction and protect the cattle industry.
What's behind the headline?
Emerging Threat to US Livestock and Public Health
The confirmation of a human New World screwworm case in Maryland signals a critical juncture in the ongoing northward spread of this parasite. Although human infections are rare, the primary concern lies with the devastating impact on livestock, particularly cattle, which underpin a significant sector of the US economy.
The Parasite's Biology and Spread
The screwworm fly lays eggs in open wounds of warm-blooded animals; larvae then burrow into living tissue, causing painful, often fatal infestations if untreated. The parasite's ability to spread rapidly across wildlife and livestock populations, combined with its recent resurgence in Central America and Mexico, underscores the urgency of containment.
Economic and Agricultural Implications
Texas, the largest US cattle producer, faces potential losses estimated at $1.8 billion if an outbreak occurs. The parasite threatens not only animal health but also food supply chains and national security. The US government's sterile fly program, reviving a successful eradication method from the 1960s, is a decisive step to mitigate this risk.
Public Health and Awareness Challenges
While the risk to human health remains low, the Maryland case highlights the need for increased awareness among healthcare providers and travelers to affected regions. Early detection and treatment are crucial, as infestations cause severe pain and require surgical intervention.
Forecast and Next Steps
The sterile fly facility under construction in Texas, alongside similar efforts in Mexico and Panama, aims to suppress screwworm populations by releasing sterile males to disrupt reproduction. This coordinated regional approach is essential to prevent re-establishment in the US. Continued surveillance, public education, and rapid response protocols will be vital to managing this threat.
Impact on Readers
For US residents, especially those in rural or livestock-heavy areas, vigilance regarding open wounds and travel history is important. The story underscores the interconnectedness of global health, agriculture, and biosecurity, emphasizing the need for proactive measures to safeguard both animal and human health.
What the papers say
The Independent's Vishwam Sankaran provides a detailed account of the parasite's biology and the US government's response, noting the construction of an $8.5 million sterile fly facility in Texas and the suspension of livestock imports from Mexico to curb spread. He quotes USDA officials emphasizing the threat to food supply and national security.
Al Jazeera highlights the economic impact on Mexican cattle exports, citing losses of $1.3 billion and the need for massive sterile fly production to push the parasite back to endemic regions. The report underscores the parasite's rapid northward movement since 2023.
The New York Post offers a human-focused perspective, describing the Maryland case and the parasite's life cycle, symptoms, and treatment challenges. It quotes epidemiologist Norman Beatty and cardiologist Salvador Hernandez to stress underdiagnosis and the importance of early detection.
Bloomberg and The Japan Times emphasize the historical eradication of screwworm in the US and the renewed concerns following recent outbreaks in Central America and Mexico, framing the Maryland case as a wake-up call.
Together, these sources provide a comprehensive view of the biological threat, economic stakes, public health implications, and governmental responses, illustrating the multifaceted challenge posed by New World screwworm's resurgence.
How we got here
New World screwworm, eradicated in the US in the 1960s, is a parasitic fly whose larvae burrow into living flesh of warm-blooded animals, causing severe tissue damage. Since 2023, outbreaks have surged in Central America and Mexico, threatening livestock and occasionally infecting humans. The US government is building sterile fly facilities to control the pest and protect the cattle industry.
Go deeper
- How does the sterile fly program work to control screwworm?
- What are the risks of screwworm to human health?
- How is the US protecting its cattle industry from this parasite?
Common question
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What Is the First US Human Case of Screwworm and Should You Be Concerned?
A Maryland resident has been diagnosed with the first confirmed case of screwworm in the US this year. This parasite, which mainly infests animals, is now spreading north from Central America, raising concerns about potential risks to humans and livestock. Curious about what screwworm is, how it infects people, and what the US authorities are doing? Keep reading to find out everything you need to know about this emerging threat.
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What is Causing the Rise of Screwworms in North America?
The recent emergence of screwworm infestations in North America has raised concerns among health officials and farmers alike. Once eradicated from the continent, this parasite is now making a troubling comeback, likely fueled by climate change and regional spread. Curious about how this affects you, what measures are being taken, and what you can do? Keep reading to find out more about the resurgence of screwworms and what it means for North America.
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What Is the Screwworm and Is It Coming to the US?
The recent confirmation of a human screwworm case in Maryland has raised concerns about this parasitic threat re-emerging in the US. Once eradicated, the screwworm is now spreading from Central America, prompting questions about its impact on humans, livestock, and what measures are being taken to prevent an outbreak. Below, we answer the most common questions about this dangerous parasite and what it means for the US.
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Are Emerging Parasites and Conflicts a Growing Global Health Threat?
Recent headlines highlight new health risks from emerging parasites like the screwworm and ongoing conflicts impacting global health. Understanding these threats is crucial for travelers, residents, and policymakers alike. Below, we explore key questions about these emerging dangers and how authorities are responding to protect public health.
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How Are Global Conflicts and Disease Outbreaks Connected?
Recent conflicts and environmental changes are more than just political issues—they can directly impact public health worldwide. From the resurgence of rare parasites in the US to ongoing wars in Gaza and Ukraine, understanding the links between conflict, climate, and disease is crucial. Below, we explore how these factors intertwine and what lessons we can learn to better prepare for future crises.
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What’s Next for US and Global Security in 2025?
As 2025 unfolds, the world faces a range of security challenges, from emerging health threats to geopolitical conflicts. Understanding these issues can help you stay informed and prepared. Below, we explore key questions about what’s ahead for US and global security this year.
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What Is the Screwworm and How Does It Threaten US Livestock and Humans?
The recent emergence of the screwworm in the US has raised alarms about its potential impact on public health and agriculture. This parasitic fly, once eradicated from North America, is now making a concerning comeback, spreading from Central America. Many are asking: What exactly is the screwworm, how does it affect humans and animals, and what is being done to stop it? Below, we answer these pressing questions and explore the broader implications of this emerging health threat.
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What is the screwworm and how did it reach the US?
The recent confirmation of the first human case of screwworm in the US has raised concerns about this parasitic threat. Once eradicated in the 1960s, the screwworm has now resurged in Central America and Mexico, prompting questions about how it arrived in the US and what risks it poses. Below, we explore what the screwworm is, how it spreads, and what measures are being taken to prevent a larger outbreak.
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What is the screwworm and how did it reach the US?
The recent confirmation of the first human case of screwworm in the US has raised concerns about this aggressive parasite's resurgence. Once eradicated in the 1960s, the screwworm is now re-emerging in North America, primarily affecting livestock but also posing potential risks to humans. Understanding how it arrived in the US, what threats it poses, and what measures are being taken can help clarify this alarming development. Below, we explore common questions about this parasite and the ongoing response to its spread.
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What is the US doing about the new screwworm threat?
The resurgence of the deadly screwworm in the US has raised serious concerns about livestock health, food security, and public safety. After the first human case was confirmed in Maryland in August 2025, questions are swirling about how the US is responding to this ancient parasite's return. Below, we explore what a screwworm is, how it reached the US, and what measures are being taken to prevent a full-blown outbreak.
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Are New Parasites and Stolen Art Threats to Global Security?
Recent developments in biological threats like the resurgence of the screwworm and the recovery of Nazi-looted art highlight complex challenges to international security. These issues raise questions about how emerging parasites can impact public health and agriculture, and how stolen cultural treasures influence diplomatic relations. Below, we explore the key concerns and what they mean for global stability.
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How Are Countries Protecting Their Cultural Heritage from Art Theft and Biological Threats?
In today's world, safeguarding our cultural treasures and agricultural health is more critical than ever. From recovering Nazi-looted art in Argentina to preventing the spread of dangerous parasites like the screwworm in the US, governments and communities are taking innovative steps to combat these threats. Curious about how these efforts work and what new technologies are making a difference? Keep reading to find out.
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What Do Recent News Stories Mean for Everyday People?
Recent headlines about emerging threats like the resurgence of screwworms and the discovery of Nazi-looted art in Argentina might seem distant or complex. But these stories can have real impacts on your daily life, from food safety to cultural heritage. Here, we explore what these stories mean for you and how you can stay informed and protected.
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What Are the Latest Legal and Scientific Responses to Today’s News?
Recent headlines highlight urgent efforts to tackle complex issues like the resurgence of the screwworm in the US and the recovery of Nazi-looted art in Argentina. These stories raise important questions about how governments and scientists are responding to threats and historical injustices. Below, we explore the key actions being taken, including legal measures, scientific innovations, and ways the public can stay informed and support these efforts.
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