New World Screwworm

News: Recently, U.S.A. reported its first human case of New World Screwworm infestation, involving a person who had travelled to El Salvador.

About New World Screwworm

• The New World Screwworm is a type of blue-grey blowfly.
• Scientific name: Cochliomyia hominivorax, which literally means “man-eater.”
• Naming: These flies are called screwworms because their larvae burrow into the tissue in a screw-like way.
• Distribution: They are usually found in South America and the Caribbean.
• Symptoms of infestation: They include wounds or sores that do not heal, bleeding from open sores, movement of larvae under the skin, and a foul odor from the infected site.
  • In severe cases, the larvae can invade deeper tissues such as the brain, leading to sepsis and possibly death.
• Life cycle and reproduction
  • A single female screwworm can lay up to 300 eggs at a time, and up to 3,000 eggs during her lifespan of 10–30 days.
  • The eggs hatch into larvae that feed on tissue, causing infestation.
  • After feeding, the larvae fall to the ground, burrow into the soil, and emerge as adult flies.
• Threat: Humans are targeted rarely, but the risk increases when people travel to regions where the parasite is present.
  • The parasite poses a serious threat to livestock, especially cattle, because open wounds on animals provide easy entry points for infestation.
• Control and eradication efforts
  • The United States eradicated the New World Screwworm in 1966 using the sterile insect technique.
    • This method involved rearing billions of sterile male flies and releasing them into the wild.
    • When wild females mated with sterile males, they did not produce offspring, which helped reduce the population.