Nematodes

Nematodes are roundworms: class Nematoda; phylum Aschelminthes; in some classifications, it is sometimes known as Nemathelminthes or a class of that phylum. There are about 12,000 classified species, but an estimated 200,000 plus are known to exist. Nematodes commonly include such worms, other than tapeworms (Cestodes) or flukes (Trematodes), as the roundworm, pin worm, hookworm, etc. They are multicellular organisms and larger than Protozoa. The adult worm multiplies by producing eggs called larvae, which become infectious in soil or in an intermediate host before infecting humans. Usually, a person will show no symptoms unless there is a heavy infestation of worms, with both coexisting until the worms grow in numbers that creates an obstruction. The following are some of the more common nematodes, except for the roundworm. Because it is a large section, it will be dealt with separately.

Hookworms (Necator americanus and Ancylostoma duodenal): Are found worldwide in warm moist soil, where the larvae penetrates the skin of those usually walking barefoot. The larvae then travel through the bloodstream to the lungs, into the alveoli, and up the trachea to the throat, where they are swallowed, ending up in the small intestines about seven weeks later. When the larvae passes through the lungs, bronchitis may develop. The teeth-like hooks of the larvae attach to the intestinal mucosa, where it injects an anticoagulant to prevent the blood from clotting. It robs the body of large amounts of blood, extracting an estimated seven million liters of blood each day from 700 million individuals around the world -- which explains its name -- Necator americanus "American murderer". Although, not all infections cause disease since it usually takes more than twenty-five adult worms to do that, but so much blood can be taken from an infestation to cause anemia. They are most likely to infect those who have a poor diet and, thus, compromised immune systems. The first sign of a hookworm infection is itchy patches of skin, pimples or blisters known as ground itch or dew itch. The skin itches for a few months until the worm dies. Other symptoms include the following: itching at the site of entry, nausea, dizziness, pneumonitis, anorexia, weight loss, and anemia. A heavy infestations will produce the following: anemia, protein deficiency, dry skin and hair, edema, distended belly, stunted growth, delayed puberty, and mental dullness. Treatments include improving nutritional status with special attention to the anemia. Adult worms are small, cylindrical, and grayish-white, with a head that is often curved in a direction opposite that of its body giving it the "hooked" appearance. Both species infect humans, but only one possesses four sharp structures like teeth, while the other has cutting plates. They are the only worms known to have teeth. These worms can live up to fifteen years in the human body, extracting .2 to .3 ml. of blood every day. This amount can be considerable since the females are known to release 10,000 to 20,000 eggs every day. Hookworm affects about 900 million people worldwide, causing 60,000 deaths, yet world agencies have spent less than a million dollars on hookworm research.
The pinworm (Enterobius vermicularis): Is the most common of all worms in the US, and the bane of a mother's existence. Over 80% of children between the ages of two and ten will be affected at one time or another. It has infested people to the tune of over 200 million worldwide, with over 40 million in the US alone. It is found in both warm and cold climates and shows no socioeconomic boundaries. Pinworms are about the size of fine silk threads a fraction of a centimeter long, but some can reach lengths of thirty cm (twelve inches). Transmission occurs through contaminated food, water, and household dust, as well as person-to-person contact. The adult female pinworm moves outside the anus, during the night, to lay her eggs. These eggs are then transferred to fingernails during scratching, and then, into the mouth where the cycle begins again. One female pinworm can deposit over 15,000 eggs that become infective immediately or within a few hours. Children can easily transmit the eggs to the entire family via the bathtub, toilet seat, and bedclothes. The eggs can stay viable for weeks on carpets, walls, sheets, and clothes. Perianal itching is the most classic sign of pinworm infestation. These threadlike ¼-inch worms have been connected to an enormous range of neurological and behavioral symptoms. Eggs are seldom found in the feces, but are laid around the anus at night. It is often necessary to treat the entire family simultaneously, repeating the process in about two weeks since reinfection is extremely common. A study published over forty years ago by Pediatrician Leo Litter, documented his ten-year study of 2,000 children, where he was able to link some unusual conditions not previously associated with parasitic infections. Some of his findings included abnormal EEG's that often mimic that of a brain tumor. Symptoms in children range from poor appetite, teeth grinding, hyperactivity, nervousness, irritability, insomnia, bed wetting, stomach aches, nausea and vomiting to more severe forms including epileptic seizures, vision problems, mental disturbances, appendicitis, and anorexia.
Strongyloides (Strongyloides stercoralis): Is a unique nematode. Sometimes called a threadworm, the mature adult can reproduce entirely in the human host or can grow freely in soil. In humans, they produce autoinfections and can remain in the body for more than thirty years. Extremely difficult to diagnose, strongyloides are found mainly in southeast Asia, the Middle East, South America, and the southeastern part of the US. The life cycle and pathology is similar to that of the hookworm, except that the eggs hatch into larvae inside the intestines before passing in the feces. The larvae enter the human body by penetrating the skin, or through pores and hair follicles. Most often penetration is between the toes or at the bottom of the feet. The larvae then travel to the intestines, where they reach maturity. If the larvae invades lung tissue or the intestinal wall, a fatal condition called disseminated strongyloides, sometimes develops. Pulmonary disorders, abdominal pain and bloating, along with greasy-stool diarrhea are the primary symptoms, with infections lasting a lifetime. The pulmonary disorders often show up in AIDS victims. The parasite seems to be relatively harmless if the immune system is functioning properly. More severe infections are characterized by abdominal pain and bloating, nausea, vomiting, alternating diarrhea and constipation, and greasy stools. The liver and pancreas ducts, the entire small bowel, colon, heart, lungs, and CNS may all be involved in malabsorption caused by the worms. With a heavy infestation, a person may complain of heartburn and tenderness, often aggravated by food intake. A peptic-ulcer like pain associated with an elevated eosinophil count on blood tests often indicates a Strongyloides infection. Lab tests will find the parasite in blood samples, since eggs are rarely found in stool samples, except after a violent purge of diarrhea.
Guinea worm (Dracunculus medinensis): Is one of the more serious discomforts of India, Africa, and Asia. Humans become infected by drinking impure water containing copepods (small crustaceans) infected with the larvae of the guinea worm. Following ingestion, the copepods die, releasing the larvae, which penetrate the stomach and intestinal wall of the host, thereby entering the abdominal cavity. The female can be over a meter long, but the male is only about two orthree centimeters (about an inch). After maturation, the worms copulate and the males die. About a year after the initial infection, the female migrates towards the surface of the skin, usually on the lower extremeties, where it will settle down just under the skin to look like a coiled vericose vein. Symptoms begin with vomiting, diarrhea, and dizziness as the worm makes its way through the body. The area produces a blister, and the patient, seeking relief, turns to bathing the area. When the lesion comes in contact with water, the female worm emerges, rupturing the blister and discharging a milky white fluid containing thousands of larvae into in water. Only water will cause her to deposit her eggs. Upon release, the eggs go on to be ingested by a crustacean called a 'cyclops' (a copepod), and, two weeks later, the cycle begins again. In an October, 1995, People Magazine article, the guinea worm was reported to have emerged from the back of a child's head and from under the tongue of a man who eventually starved to death because the area was too painful to permit eating. Native medicine men remove the worms slowly by winding them onto a stick. It is a long process, requiring only a turn or two a day. It is not uncommon to see people walking around with a stick taped to their legs and good-sized worms coiled around them. If the procedure is not done properly, bacterial infections develop. After serious efforts towards hygiene and purified water, the disease is being eradicated. Where once several million people were affected, the numbers are now fewer than 200,000.