Detect the Borer Worm: Essential Tips to Prevent Its Spread!

MEXICO CITY (apro) – On Friday, April 18, the Health Ministry reported the first human case of myiasis—a parasitic disease—caused by the screwworm (Cochliomyia hominivorax); the patient is a 77-year-old woman from the municipality of Acacoyagua, Chiapas.

According to the report, the woman is in stable condition at the Ciudad Salud High Specialty Hospital in Tapachula, while state services in Chiapas conduct the necessary investigation.

#ComunicadoSalud

Health Ministry announces detection of the first confirmed human case of myiasis by screwworm in livestock (Cochliomyia hominivorax) pic.twitter.com/R5Co8iJoqH

— Epidemiology Mexico (@DGEMexico) April 18, 2025

Meanwhile, the National Service of Health, Safety, and Agri-Food Quality (Senasica) is involved in training for epidemiological surveillance, prevention, and control of myiasis by Cochliomyia hominivorax, the ministry noted.

Understanding the Screwworm

The screwworm is an infestation caused by the larvae of the fly Cochliomyia hominivorax, which feeds on the living tissue of mammals and, occasionally, birds, according to the Ministry of Agriculture and Rural Development (SADER).

Flies lay their eggs on superficial wounds; the larvae hatch within 12 to 24 hours and feed on the tissue for four to eight days, causing severe damage to the animal.

This plague is a significant threat to livestock health and can occasionally affect humans as well.

Detecting screwworms in livestock:

• Infestation in small wounds, including tick bites.
• Wounds on newborns’ navels.
• Vulvar or perineal regions of females.
• Infected animals tend to isolate from the group, show signs of depression, loss of appetite, and discomfort at the wound sites.

Common clinical symptoms of myiasis:

• Fever.
• Depression.
• Loss of appetite.
• Decreased milk production and weight gain.

What do infested wounds look like?

According to the Ministry of Agriculture, the wounds are usually large and oozing, exuding blood and emitting a rotten flesh odor. Larvae can often be found clumped at the base. Without proper treatment, myiasis can be fatal within two weeks.

Spread of the screwworm:

• Transportation of parasitized animals: The larval stage is protected in the wounds, allowing it to spread over great distances.
• Inadequate transport: Vehicles not properly cleaned can harbor larvae.
• Tourism in endemic areas: People returning with infested wounds can introduce the parasite to new areas.
• Mobility of flies: They can travel up to 290 kilometers in a week.
• Scientific research: Collecting insects in endemic zones can infect plague-free areas.

Tips to Prevent an Infestation

• Control the import of animals from countries affected by the plague.
• Strengthen biosecurity measures at production units.
• Promptly treat any wounds on livestock.
• Conduct daily checks on animals.
• Transport only healthy animals.
• Report any suspicion of infestation to Senasica for assistance.

If you suspect an infestation, the Mexican government provides the following contact methods:

• Phone: 01 (800) 751 2100 and 01 (55) 5905 1000.
• Email: sive.dgsa@senasica.gob.mx or gestioncpa.dgsa@senasica.gob.mx.