Flesh-eating screwworm parasite detected in person in US for first time

A case of the flesh-eating screwworm parasite has been detected in a person in the United States for the first time.

The parasitic flies eat cattle and other warm-blooded animals alive, with an outbreak beginning in Central America and southern Mexico late last year.

It is ultimately fatal if left untreated.

The case in the US was identified in a person from Maryland who had travelled from Guatemala.

Beth Thompson, South Dakota's state veterinarian, told Reuters on Sunday that she was notified of the case within thelast week.

A Maryland state government official also confirmed the case.

The person was treated and prevention measures were implemented, Reuters reports.

The Centres for Disease Control and Prevention (CDC) and the Maryland Department of Health did not immediately respond to requests for comment.

What is screwworm?

The female screwworm fly lays eggs in the wounds of warm-blooded animals and once hatched, hundreds of screwworm larvae use their sharp mouths to burrow through living flesh.

It can be devastating in cattle and wildlife, and has also been known to infect humans.

Treatment is onerous, and involves removing hundreds of larvae and thoroughly disinfecting wounds. They are largely survivable if treated early enough.

The confirmed case is likely to rattle the beef and cattle futures market, which has seen record-high prices because of tight supplies.

The US typically imports more than a million cattle from Mexico each year to process into beef. The screwworm outbreak could cost Texas - the biggest cattle-producing state - $1.8bn (£1.3bn) in livestock deaths, labour costs and medicationexpenses.

The United States Department of Agriculture (USDA) has set traps and sent mounted officers along the border, but it has faced criticism from some cattle producers and market analysts for not acting faster to pursue increased fly production via a sterile fly facility.

What is a sterile fly facility?

The case also comes just one week after the US agriculture secretary, Brooke Rollins, travelled to Texas to announce plans to build a sterile fly facility there in a bid to combat the pest. Ms Rollins had pledged repeatedly to keep screwworm out of the country.

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A sterile fly facility produces a large number of male flies and sterilises them - these males are then released to mate with wild female insects, which collapses the wild population over time. This method eradicated screwworm from the US in the 1960s.

Mexico has also taken efforts to limit the spread of the pest, which can kill livestock within weeks if not treated. It had started to build a $51m sterile fly production facility.

The USDA has previously said 500 million flies would need to be released weekly to push the fly back to the Darien Gap, the stretch of rainforest between Panama and Colombia.