'Gross' parasite could return to California after almost 60 years

"New World screwworm larvae are less than an inch long but can cause major injuries in humans, including wounds and open sores if they burrow into the host. The CDPH issued its warning in September after a rare human case in the U.S. was reported over the summer. That case was found in a traveler in Maryland, who was diagnosed with the infection."

"She explained that the infestation happens when an adult female fly lays eggs in the wound of a human or animal host. Gandhi said even a cut as small as a razor nick can be a problem. After the eggs hatch, the larvae can burrow into the host's body. "It's the larvae that are those small maggots that cause the infestation," Gandhi said. "It can really be very painful.""

"Previously endemic to the U.S., the New World screwworm was eradicated in 1966 across the country through fly control programs. It had been declared eradicated in parts of Central America and Southern Mexico, as well, but in recent years returned and caused infections there, raising concerns it could soon come back to the U.S. In August, the USDA announced new plans to keep the insect from regaining a foothold in the U.S., including assisting Mexico with controlling the pest."

The California Department of Public Health issued a traveler warning in September after a rare human case of New World screwworm infection was reported in Maryland over the summer. New World screwworm larvae are under an inch long and can burrow into wounds, causing painful infestations, open sores, and major injuries. Adult female flies lay eggs in even tiny cuts or razor nicks, and hatched larvae (maggots) cause the tissue damage. The parasite can devastate closely packed livestock herds. The screwworm was eradicated in the U.S. in 1966 but has returned in parts of Central America, prompting USDA prevention plans including assistance to Mexico.

Read at SFGATE