Finding something unexpected inside a chicken egg is startling, but actual worms in eggs are extremely rare. In most cases, what looks like a worm turns out to be a normal part of the egg’s structure or a harmless tissue fragment. When a real parasitic worm does end up inside an egg, it’s almost always a large roundworm called Ascaridia galli, and it looks unmistakably like a worm: a dense, white, spaghetti-like strand that’s several inches long.
What a Real Worm Looks Like Inside an Egg
The roundworm that infects chickens is thick, white, and impossible to mistake for anything else once you know what you’re looking at. Female worms range from about 2.5 to nearly 5 inches long and are roughly 1 to 2 millimeters wide. Males are slightly smaller, around 1 to 3 inches. Both are densely white, stout, and smooth. If you cracked open an egg and found one, you’d see what looks like a short piece of cooked spaghetti sitting in the egg white or coiled near the yolk.
A much rarer parasite, the oviduct fluke, has also been documented inside eggs. This is a flat, leaf-shaped organism rather than a round worm, and it’s far smaller. A confirmed case in North Carolina identified one inside an egg, but the researchers noted this is exceptionally uncommon in the United States. Oviduct flukes require a specific life cycle involving aquatic snails and dragonflies, so they’re essentially impossible in eggs from chickens that don’t have access to ponds or streams.
What You’re Probably Actually Seeing
The vast majority of “worm sightings” in eggs are one of two normal egg structures: the chalazae or a meat spot.
The chalazae are twisted, rope-like strands of egg white that anchor the yolk in the center of the egg. Every egg has them. They appear as white, springy, cord-like structures on either side of the yolk, and in a very fresh egg they can look especially prominent and firm. They’re not a defect. They’re a sign the egg is fresh, because chalazae break down as eggs age. If what you found is white, attached to the yolk, and has a twisted or spiraled texture, it’s almost certainly a chalaza.
Meat spots are brownish deposits, usually found in the egg white, made up of small bits of tissue that broke off inside the hen’s reproductive tract during egg formation. They can look like dark flecks or small irregular clumps. Blood spots are similar but reddish, caused by a tiny blood vessel rupturing as the egg was released. As eggs age, blood spots can fade and start to resemble meat spots. Neither type is harmful, and both are common enough that commercial egg producers use a process called candling (shining a bright light through the shell) to catch and remove eggs with visible spots before they reach stores.
Here’s a quick way to tell the difference: chalazae are white, ropy, and connected to the yolk. Meat spots are brownish, irregular, and float freely. A real roundworm is thick, uniformly white, several inches long, and looks like a distinct organism with a body shape, not a strand of egg protein.
How a Worm Ends Up Inside an Egg
Chickens pick up roundworm eggs by pecking at contaminated soil or droppings. The parasites mature in the bird’s intestines. In rare cases, an adult worm travels from the intestine through the cloaca (the shared opening for the digestive and reproductive tracts) and migrates up the oviduct, which is the tube where eggs are formed. If the worm is in the right place at the right time, it gets encased inside the shell as the egg forms around it.
This migration is genuinely uncommon. The oviduct and intestinal tract share an exit point, but the worm has to travel against the normal flow of egg production to end up inside a forming egg. Commercial egg operations use candling to detect any abnormalities before eggs are sold, which is why you’ll almost never encounter this in store-bought eggs. Backyard flocks, which aren’t typically candled, account for nearly all reported cases.
Is It Dangerous to Eat?
Finding a roundworm in an egg is an aesthetic problem, not a food safety one. The Merck Veterinary Manual classifies it specifically as “an aesthetic rather than a public health problem.” Ascaridia galli is a chicken parasite. It doesn’t infect humans. Cooking the egg would kill the worm regardless. That said, most people would understandably throw the egg away.
Preventing Worms in Backyard Flocks
If you raise chickens and found a worm in an egg, the hen that laid it likely has a significant intestinal worm burden. A single worm making it into an egg suggests many more are living in the bird’s gut.
Fenbendazole is the only dewormer currently approved in the United States for treating roundworms in chickens. It’s available as a medicated feed for turkeys or a water-soluble formula for chickens. When used according to label directions, there’s no required withdrawal period for eggs or meat, meaning you can continue eating eggs from treated birds right away. There are currently no approved dewormers for tapeworms in poultry in the U.S.
Reducing parasite exposure starts with management. Rotate your flock to fresh ground when possible, keep the coop and run clean and dry, and avoid overcrowding. Worm eggs survive in soil for long periods, so the same patch of ground used year after year builds up a heavy parasite load. If you want to screen eggs yourself, hold each one up to a bright flashlight in a dark room. This DIY version of candling can reveal shadows or unusual masses inside the shell before you crack it open.