The new year begins with a new warning for those who work with animals in Texas. The state Parks and Wildlife Department is asking hunters and other outdoor enthusiasts to keep an eye out for animals that may be affected by dangerous “maneater” parasites of flies that lay eggs in open wounds, nostrils, eyes and mouth.
The advisory, posted by the department on December 30, was issued for outdoor enthusiasts in South Texas after the New World Screwworm was recently found in a cow in the southern Mexican state of Chiapas.
According to the Texas Parks and Wildlife Department, the New World Screwworm has made its way further north across America.
“As a protective measure, animal health officials are asking those along the border in south Texas to monitor wildlife, livestock and pets for clinical signs of NWS and immediately report potential cases,” the department said.
John Kucharski, Public Domain, via Wikimedia Commons
What is the New World Screwworm?
According to the United States Department of Agriculture, the New World Screwworm is “a devastating pest.”
“When NWS fly larvae (maggots) burrow into the flesh of a living animal, they cause serious, often fatal damage to the animal,” the USDA says. “NWS can infect livestock, pets, wildlife, sometimes birds, and rarely people.”
The Texas Parks Department says the maggots will lay eggs in “open wounds or openings of living tissue such as nostrils, eyes or mouth.” One such infestation is known as New World screwworm myiasis.
“These eggs hatch into dangerous parasitic larvae, and the maggots burrow or screw into the flesh with sharp mouth hooks. Wounds can become larger and an infestation can often cause serious, fatal damage or death to the infected animal.”
The scientific name for the parasite, Cochliomyia hominivoraxis roughly translated as “maneater,” according to the USDA’s Animal and Plant Health Inspection Service.
“It’s an apt name,” the agency added, saying that the screwworm was once widespread in the US, with 230,000 reported cases as recently as 1935. But then scientists developed a way to release sterilized male blow flies, and since only female blow flies mate ever, the agency says it has “effectively removed that female and her potential offspring from the population.”
The elimination of the New World Screwworm is believed to have saved U.S. farm workers nearly $900 million in lost livestock annually, the agency said.
Where are New World screwworms found?
New World screwworms are endemic to Cuba, Haiti, the Dominican Republic and countries in South America. However, the USDA says cases of the parasite are also spreading north to Costa Rica, Nicaragua, Honduras, Guatemala and Mexico.
“Although USDA eradicated NWS from the United States in 1966 using sterile insect techniques, there is a continuing risk of reintroduction into the United States,” says the USDA’s Animal and Plant Health Inspection Service. “To prevent the northward movement of this pest from South America to NWS-free areas in Central and North America, APHIS is working with Panama to maintain a barrier zone in eastern Panama.”
What You Need to Know About New World Screwworm Myiasis
The Texas Parks and Wildlife Department says that female New World Screwworm flies “are attracted to the odor of a wound or natural opening of a living, warm-blooded animal.” There, just one fly can lay as many as 300 eggs at a time, and during its lifetime it can lay as many as 3,000 eggs.
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After the eggs hatch, they become larvae or maggots that burrow into an opening to feed. Once they feed, they drop to the ground, burrow into the soil and emerge as adult flies. The adult flies can travel long distances, the department says, “and the movement of infected livestock or wildlife can accelerate the spread.”
Signs of NWS Myiasis include irritable or depressed behavior, loss of appetite, head shaking, the smell of rotting flesh, the presence of maggots in wounds, and isolation from other animals or people.
To prevent an infestation, Texas officials say to clean and cover all wounds when spending time outdoors, especially in NWS-affected areas, and to apply insect repellent to outdoor clothing.
