Public health specialists are warning about the dangers of hidden parasites after media reports of a 30-year-old Fresno, Calif., man who showed up at a hospital emergency room with a 5 ½-foot-long tapeworm he may have acquired from improperly prepared sushi.

Dr. Kenny Banh — an emergency physician at the University of California-San Francisco in Fresno — recounted case on the podcast “This Won’t Hurt a Bit.”

Bahn said the man showed up in the emergency room of UCSF Fresno's Community Regional Medical Center last August and told him he was stricken with stomach cramps and bloody diarrhea after eating sushi. Then, while using the bathroom, he noticed something hanging from his rear end, which he was able to remove.

“He was like, ‘Oh my goodness, my guts are coming out from me,’ ” Banh told the Washington Post.

“He picks it up and looks at it and what does it do? It starts moving. He was like, ‘That's a worm.’ ”

Bahn said the man was carrying a plastic grocery bag that contained a tapeworm, a parasite that can invade the digestive tract of animals and humans.

He said the patient was convinced he got the tapeworm from eating raw fish because he ate sushi or sashimi almost daily.

“You have to be aware,” Bah said, explaining improperly prepared raw fish and other foods can contain and spread parasites.

Concerns about sushi-related parasites have been rising in recent years. U.S. Food and Drug Administration has released guidelines for controlling parasites in seafood by cooking the food or freezing it for certain amounts of time.

Last January 2017, the Centers for Disease Control and Prevention reported in the journal Emerging Infectious Diseases that wild salmon caught in Alaska's icy waters were found to be infected by a Japanese tapeworm known as Diphyllobothrium nihonkaiense.

“Salmon from the American and Asian Pacific coasts and elsewhere pose potential dangers for persons who eat these fish raw,” the researchers concluded.

Diphyllobothrium latum are among the most common tapeworms and can grow up to 30 feet, and live for years in the human body.

Infections are usually asymptomatic, but can cause abdominal pain, diarrhea and vomiting, according to the CDC. And, doctors say, they are treated pretty easily with medication.

Last May, researchers reported in the British Medical Journal Case Reports that sushi's growing popularity may be driving an increase in parasite infections.

In one case, doctors found parasite larvae in the gut lining of a 32-year-old man who had recently eaten sushi. The man had been vomiting with stomach pain and a fever, but doctors did not suspect the parasite until the man mentioned recently eating sushi.

According to The Guardian, the worm was from the genus Anisakis, which causes the condition known as anisakiasis.

"When humans eat raw or undercooked infected fish or squid, they ingest nematode larvae," the CDC reports. "Once inside the human body, the larvae can invade the gastrointestinal tract. Eventually, the parasite dies and produces an inflamed mass in the esophagus, stomach, or intestine."

According to the CDC, some people will experience a tingling sensation after or while eating raw or undercooked fish or squid, which could actually be the parasite moving in the mouth or throat.

Tapeworms are only one type of parasite that can infect the human body. Others that can enter the human body through food and water include:

Giardia — a protozoan that causes giardiasis in humans. This parasite is ingested via contaminated food and water, and affects the small intestine as it begins to multiply and colonize.

Symptoms: Flatulence, diarrhea, abdominal cramps, fatigue, weakness, and weight loss. Giardiasis symptoms are frequently found in travelers but resolve in a few weeks without treatment.

E. vermicularis — a nematode parasite that strikes 209 million adults and 30 percent of children worldwide, according to a study published in the American Family Physician journal reports. This parasite is also present in the intestine and the infection may last four to six weeks.

Symptoms: Perianal and vaginal itching, urinary tract infection, appendicitis, and weight loss.

Filarial worms — a roundworm that causes filariasis. This parasite circulates in the blood and, upon maturing, enters the lymphatic system and develops while it lives there for more than five years. It affects the lymphatic nodes and causes retention of fluids resulting in swelling.

Symptoms: Swollen feet and lower limbs, skin hardening and thickening.

Hookworm — also known as necator americanus is found widely in the Americas and Caribbean. The hookworm attaches itself to the intestinal walls and feeds on human blood.

Symptoms: Anemia, physical and mental retardation in children.

Guinea worm — a roundworm that causes Guinea worm disease by entering the stomach and intestine from untreated water.

Symptoms: There are no significant visible symptoms when the parasite enters the body. But a year later, the worm ruptures the skin surface, often near the lower limbs, causing painful wounds that can lead to bacterial infections and blood poisoning.