New world screwworm: A focused review for the emergency medicine clinician

New World Screwworm (NWS), or Cochliomyia hominivorax, is a potentially fatal disease due to severe larvae infestation and tissue destruction. A resurgence has been reported.

This narrative review provides a focused overview of NWS for the emergency clinician, including the epidemiology, presentation, diagnosis, and management of the disease.

NWS is endemic to tropical and subtropical America. While previously eradicated in the U.S., several human cases have been recently reported. This insect primarily infests livestock but may also affect humans. Female flies are attracted to mucosal surfaces and wounds and lay hundreds of eggs. Once hatching, larvae burrow into these surfaces and cause extensive damage by ingesting live tissue. Humans at risk include those with significant immunocompromise, open wounds, and those around animals. Infested patients present with severe swelling, bleeding, pain, and open, malodorous wounds. Larvae are usually visible in the wound. Bacterial superinfections may also occur. Suspected cases should be reported to the local or state public health department and the Centers for Disease Control and Prevention. Diagnosis includes morphologic identification of larvae removed from a wound. Larvae should be placed in a leak-proof container with 70% ethanol. Serum laboratory testing may also be needed in patients with evidence of bacterial superinfection and sepsis. Treatment includes removal of all larvae and often extensive debridement. Reevaluation of the wound within 48 h is recommended. Antibiotics are necessary for those with bacterial superinfection.

Emergency clinicians should be aware of the presentation, diagnosis, evaluation, and management of NWS to ensure optimal outcomes.