A parasitic fly once confined to South America is now spreading northward — and Canadian travellers should take note. The New World Screwworm (NWS) has breached biological barriers that kept it at bay for decades, raising a question: what are the travel implications of the NWS outbreak for Canadians heading to Mexico, Central America, and the Caribbean?
The short answer is that the risk remains low — but it is not zero. The Public Health Agency of Canada and infectious disease specialists have issued advisories urging heightened awareness, particularly for those with open wounds or cuts who plan to visit affected regions. Destinations like Costa Rica, the Dominican Republic, and parts of Mexico are among those drawing attention.
Experts are not telling Canadians to cancel their plans. This is about being informed, not alarmed. Knowing what the NWS is, how it spreads, and what precautions to take could make the difference between a trip that goes smoothly and one that doesn’t.
Geographic Spread and Human Toll of the NWS Outbreak
The New World Screwworm outbreak began spreading beyond its traditional containment zone in 2023, when a barrier on the Panama–Colombia border failed. That barrier had been maintained since 2006 through the release of roughly 15 million sterile flies weekly — a system that worked, until it didn’t.
Once breached, the parasite moved quickly through Central America, reaching Mexico by December 2024. By September 2025, it had been confirmed in seven southern Mexican states: Chiapas, Campeche, Oaxaca, Quintana Roo, Tabasco, Veracruz, and Yucatán. The situation escalated when it reached Tamaulipas and Nuevo León — two states bordering Texas — and by June 2026, the first U.S. livestock case in decades was confirmed near La Pryor, Texas, approximately 50 miles from the border.
The cumulative toll across Mexico and Central America has exceeded 171,700 animal cases and more than 2,070 human cases, with 10 deaths reported according to the CDC. Chiapas alone accounts for 43 of Mexico’s 49 human cases — a detail Canadian travellers heading to that region should keep in mind.
Real Cases and Health Risks for Canadian Travellers
An 80-year-old Canadian man learned this the hard way. After falling during a trip to Costa Rica, he had 30 to 40 larvae removed from his wound before boarding a flight to Toronto — where doctors had to extend an incision to extract more. The larvae were confirmed as New World Screwworm. The case, published in Travel Medicine and Infectious Disease, is not an isolated one: local infectious disease specialists in Toronto have reported seeing multiple cases in travellers returning from Costa Rica.
The parasite is an equal-opportunity threat. Any break in the skin is a potential entry point, as are the eyes, ears, nose, mouth, and other mucous membranes. Travellers who spend time near livestock or sleep outdoors face a higher risk. Symptoms include rapidly worsening, foul-smelling wounds with intense pain — some patients can actually feel larvae moving beneath the skin.
When caught early, the condition is treatable. But delays can lead to nerve damage, secondary infections, sepsis, and, in cases involving vital areas, death.
Prevention Tips and Post-Travel Steps for Canadians
Protecting yourself starts with a few straightforward habits:
- Avoid close contact with livestock, pets, or wildlife in outbreak areas, and keep all wounds — no matter how minor — clean and covered.
- Wear loose-fitting, long-sleeved clothing to reduce exposed skin; use EPA-registered insect repellent and consider permethrin-treated garments.
- Sleep indoors or in screened rooms whenever possible.
- If a wound becomes painful, starts to smell, or isn’t healing as expected, seek medical attention immediately; do not attempt to remove larvae yourself.
Full extraction, sometimes surgical, along with antibiotics, is required to prevent secondary infection.
One detail worth knowing before you land back in Canada: there is currently no formal protocol for suspected human NWS cases in Canadian provinces. That means returning travellers with concerning symptoms should see a doctor promptly and be upfront about where they’ve been. The Government of Canada updates its travel advisories regularly, so checking them before departure is always a smart move.
Planning a trip to Mexico, the Caribbean, or Central America? Travel with confidence.
While health advisories like the New World Screwworm outbreak may sound alarming, they don’t have to derail your dream vacation — they just mean smarter planning matters more than ever. That’s where Air Valet Travel comes in. As a trusted travel agency in Mississauga, Air Valet’s dedicated travel experts handle every detail of your journey, from flights and accommodations to destination-specific guidance and travel insurance options. Whether you’re escaping to a sunny beach or exploring a vibrant cultural destination, their personalized approach ensures your trip is seamless, safe, and unforgettable. Let Air Valet take the stress out of travel planning — so you can focus on enjoying the adventure.
