Types of Human Internal Worms

The term “internal worms” refers to parasites that infect the digestive system of mammals and live off the food its host eats. While most people associate internal worms with household pets and wild animals, humans are also susceptible to some types of internal worms. Most worm infections in humans are easily treatable, though infestations may lead to serious health problems without medical attention, which typically takes the form of prescription medications.

Tapeworms

• Several varieties of tapeworms can infect humans, such as the pork tapeworm (Taenia solium), the beef tapeworm (Taenia saginata), the dwarf tapeworm (Hymenolepis nana) and the fish tapeworm (Diphyllobothrium latum). Humans obtain tapeworm infections from ingesting the eggs or larvae of the worms. Typically, this occurs from eating contaminated meat or coming in contact with animal stool and not practicing proper hygiene afterward. Adult tapeworms grow up to 50 feet in length and live up to 20 years, reports the Mayo Clinic. In most cases, tapeworms may attach to your intestines or pass through your body through your stool, but sometimes tapeworms escape your digestive systems and form cysts on your brain, liver or lungs. These invasive infections pose a risk for seizures, dementia and organ damage, and may require surgery to repair damage or remove the cysts.

Ascarias

• The ascarias roundworm, one of the most common internal worms to infect humans, is found in approximately 25 percent of the world's population, particularly in developing nations, reports the Mayo Clinic. At only 16 inches in length, the worms are small. Ascarias infections are known as ascariasis and typically occur when humans eat vegetables or fruits grown in soil infested with the worms' eggs. The eggs hatch in the body and grow for around two months before traveling to the end of the digestive tract to lay eggs. When feces containing the worms is mixed with soil, the cycle of infection begins again. In most cases, ascariasis causes little or no symptoms, but large infestations may cause vomiting, nausea, severe weight loss and abdominal pain.

Pinworms

• Another type of roundworm, pinworms are only .2 to .4 inches in length, according to the Mayo Clinic. The life cycle of pinworms is similar to that of ascarias, except the worms come from a wider variety of sources, including contaminated foods, drinks and hard surfaces. The microscopic size of pinworms makes them difficult to detect, and like the ascarias, the parasites rarely cause symptoms with minor infections. More severe cases of infestation produce anal itching, insomnia and nausea that comes and goes.

Trichinella Spiralis

• Trichinella spiralis is a type of roundworm found in some types of meat-eating mammals like hogs, bears and foxes. The larvae of the Trichinella spiralis infects humans through tainted meat and causes an infection known as trichinosis. In the United States, only around 40 cases of trichinosis occur each year, according to the U.S. National Library of Medicine. In most cases, trichinosis infections are mild and cause only fever, muscle pain, diarrhea and abdominal pain. More severe infections can lead to inflammation of your heart muscle, brain, lungs, kidneys or the membrane that surrounds your brain and spinal cord. These severe cases often require corticosteroid medications to treat the inflammation in addition to antiparasitic drugs to kill the Trichinella, reports the Mayo Clinic.