🧪 Ivermectin evidence limited in human screwworm
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PAHO/WHO warned that human myiasis from Cochliomyia hominivorax (New World screwworm) is rising fast: 1,355 cases and 5 deaths were reported from Jan. 1 to Sept. 2026 in 6 countries, a 62% increase vs. the previous year. In its epidemiological alert, PAHO/WHO said evidence for systemic ivermectin is limited and it does not replace complete larval removal and wound care.
Why It Matters To Your Practice
NPs and PAs are often the first clinicians to spot the real clue: larvae in a wound, mucous membrane involvement, or a patient describing a sensation of movement.
Risk is highest in people living in or traveling to affected areas who have untreated wounds, chronic ulcers, recent surgical wounds, or difficulty with self-care.
Myiasis is not spread person to person, but without treatment the infestation can be fatal.
Ocular, nasal, oral, and airway involvement need urgent evaluation.
Clinical Benefits
Your frontline assessment can speed diagnosis and treatment before tissue damage worsens.
PAHO/WHO recommends considering myiasis when wounds or mucous membranes contain larvae or when patients report movement in the lesion.
Collect representative larval samples for species identification, but do not wait for confirmation to begin management.
Core treatment is complete larval removal, lesion irrigation, and debridement of necrotic tissue when indicated.
Managing Risks
Do not rely on systemic ivermectin as a substitute for hands-on source control; evidence remains limited in human screwworm.
Use antimicrobials only when there is secondary bacterial infection.
Missed larvae can prolong infestation, so careful wound inspection and follow-up matter.
Cross-country case counts should be interpreted cautiously because surveillance systems and case definitions differ.
The Bottom Line
This is a growing One Health problem across Central America, Mexico, and parts of the U.S., and your clinical vigilance is central to catching it early.
For NPs and PAs, this is not “supporting” work — it is decisive frontline medicine: recognize screwworm, remove larvae promptly, manage the wound, and escalate urgent anatomic involvement fast.
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