For the first time in the United States, a case of parasitism by the so-called screwworm fly (Cochliomyia hominivorax), an insect that consumes living tissue of animals and humans, has been detected. It can be fatal if not treated in time.

The case concerns an individual from the state of Maryland, who had recently traveled from Guatemala. The diagnosis was reported to health authorities within the past week, and the individual received immediate treatment.

What is the screwworm

The female fly lays its eggs on open wounds of animals or humans. When the eggs hatch, hundreds of larvae begin feeding on living tissue, creating tunnels in the flesh. The phenomenon can cause severe damage or even death if there is no timely intervention.

Treatment is difficult and involves removing hundreds of larvae and disinfecting the wounds. If diagnosed promptly, survival is almost certain; however, the damage to animals – mainly cattle – can be incalculable.

Impacts on livestock and the economy

The emergence of this case comes at a time when the U.S. beef market is recording historically high prices due to limited supplies.

The potential spread of the parasite is raising concerns among producers, as it is estimated that just in Texas, losses from a possible outbreak could reach $1.8 billion, including animal deaths, medications, and labor costs.

The U.S. imports over one million cattle annually from Mexico, which increases the risk of spread.

The battle with sterilized insects

To address the threat, the U.S. Department of Agriculture (USDA) has set up traps and deployed inspectors along the borders. However, it has been criticized for delaying the implementation of the most proven effective method: the release of sterilized insects.

This technique – which eradicated the screwworm from the U.S. in the 1960s – is based on breeding and sterilizing a large number of male flies, which, when mating with wild females, prevent them from reproducing, gradually leading to population collapse.

Last week, the Secretary of Agriculture announced the construction of a new sterilized insect production facility in Texas, pledging to keep the parasite out of the U.S. At the same time, Mexico is investing $51 million to build its own facility.

According to estimates, 500 million sterilized flies would need to be released weekly to contain the parasite behind the Darién, the dense tropical forest that separates Panama from Colombia.