Strongyloides stercoralis. Source: CDC
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Strongyloidiasis

Strongyloidiasis is a human parasitic disease caused by the nematode (roundworm) Strongyloides stercoralis. Other Strongyloides include S. fülleborni, which infects chimpanzees and baboons and may produce limited infections in humans. more...

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Life Cycle

The Strongyloides life cycle is more complex than that of most nematodes with its alternation between free-living and parasitic cycles, and its potential for autoinfection and multiplication within the host. Two types of cycles exist:

  • Free-living cycle: The rhabditiform larvae passed in the stool can either molt twice and become infective filariform larvae (direct development) or molt four times and become free living adult males and females that mate and produce eggs from which rhabditiform larvae hatch. The latter in turn can either develop into a new generation of free-living adults, or into infective filariform larvae. The filariform larvae penetrate the human host skin to initiate the parasitic cycle.
  • Parasitic cycle: Filariform larvae in contaminated soil penetrate the human skin , and are transported to the lungs where they penetrate the alveolar spaces; they are carried through the bronchial tree to the pharynx, are swallowed and then reach the small intestine. In the small intestine they molt twice and become adult female worms. The females live threaded in the epithelium of the small intestine and by parthenogenesis produce eggs, which yield rhabditiform larvae. The rhabditiform larvae can either be passed in the stool (see "Free-living cycle" above), or can cause autoinfection. In autoinfection, the rhabditiform larvae become infective filariform larvae, which can penetrate either the intestinal mucosa (internal autoinfection) or the skin of the perianal area (external autoinfection); in either case, the filariform larvae may follow the previously described route, being carried successively to the lungs, the bronchial tree, the pharynx, and the small intestine where they mature into adults; or they may disseminate widely in the body. To date, occurrence of autoinfection in humans with helminthic infections is recognized only in Strongyloides stercoralis and Capillaria philippinensis infections. In the case of Strongyloides, autoinfection may explain the possibility of persistent infections for many years in persons who have not been in an endemic area and of hyperinfections in immunodepressed individuals.

Geographic distribution

Tropical and subtropical areas, but cases also occur in temperate areas (including the South of the United States). More frequently found in rural areas, institutional settings, and lower socio-economic groups.

Clinical features

Frequently asymptomatic. Gastrointestinal system symptoms include abdominal pain and diarrhea. Pulmonary symptoms (including Loeffler’s syndrome) can occur during pulmonary migration of the filariform larvae. Dermatologic manifestations include urticarial rashes in the buttocks and waist areas. Disseminated strongyloidiasis occurs in immunosuppressed patients, can present with abdominal pain, distension, shock, pulmonary and neurologic complications and septicemia, and is potentially fatal. Blood eosinophilia is generally present during the acute and chronic stages, but may be absent with dissemination.

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Indigestion
From Gale Encyclopedia of Medicine, 4/6/01 by Rebecca J. Frey

Definition

Indigestion, which is sometimes called dyspepsia, is a general term covering a group of nonspecific symptoms in the digestive tract. It is often described as a feeling of fullness, bloating, nausea, heartburn, or gassy discomfort in the chest or abdomen. The symptoms develop during meals or shortly afterward. In most cases, indigestion is a minor problem that often clears up without professional treatment.

Description

Indigestion or dyspepsia is a widespread condition, estimated to occur in 25% of the adult population of the United States. Most people with indigestion do not feel sick enough to see a doctor; nonetheless, it is a common reason for office visits. About 3% of visits to primary care doctors are for indigestion.

Causes & symptoms

Physical causes

The symptoms associated with indigestion have a variety of possible physical causes, ranging from commonplace food items to serious systemic disorders:

  • Diet. Milk, milk products, alcoholic beverages, tea, and coffee cause indigestion in some people because they stimulate the stomach's production of acid.
  • Medications. Certain prescription drugs as well as over-the- counter medications can irritate the stomach lining. These medications include aspirin, NSAIDs, some antibiotics, digoxin, theophylline, corticosteroids, iron (ferrous sulfate), oral contraceptives, and tricyclic antidepressants.
  • Disorders of the pancreas and gallbladder. These include inflammation of the gallbladder or pancreas, cancer of the pancreas, and gallstones.
  • Intestinal parasites. Parasitic infections that cause indigestion include amebiasis, fluke and tapeworm infections, giardiasis, and strongyloidiasis.
  • Systemic disorders, including diabetes, thyroid disease, collagen vascular disease.
  • Cancers of the digestive tract.
  • Conditions associated with women's reproductive organs. These conditions include menstrual cramps, pregnancy, and pelvic inflammatory disease.

Psychologic and emotional causes

Indigestion often accompanies an emotional upset, because the part of the nervous system involved in the so-called "fight-or-flight" response also affects the digestive tract. People diagnosed with anxiety or somatoform disorders frequently have problems with indigestion. Many people in the general population, however, will also experience heartburn, "butterflies in the stomach," or stomach cramps when they are in upsetting situations--such as school examinations, arguments with family members, crises in their workplace, and so on. Some people's digestive systems appear to react more intensely to emotional stress due to hypersensitive nerve endings in their intestinal tract.

Specific gastrointestinal disorders

In some cases, the patient's description of the symptoms suggests a specific digestive disorder as the cause of the indigestion. Some doctors classify these cases into three groups:

Esophagitis type

Esophagitis is an inflammation of the tube that carries food from the throat to the stomach (the esophagus). The tissues of the esophagus can become irritated by the flow (reflux) of stomach acid backward into the lower part of the esophagus. If the patient describes the indigestion in terms of frequent or intense heartburn, the doctor will consider gastroesophageal reflux disease (GERD) as a possible cause. GERD is a common disorder in the general population, affecting about 30% of adults.

Peptic ulcer type

Patients who smoke and are over 45 are more likely to have indigestion of the peptic ulcer type. This group also includes people who find that their indigestion is relieved by taking antacids or eating a small amount of food. Patients in this category are often found to have Helicobacter pylori infections. H. pylori is a rod-shaped bacterium that lives in the tissues of the stomach and causes irritation of the mucous lining of the stomach walls. Most people with H. pylori infections do not develop chronic indigestion, but the organism appears to cause peptic ulcer disease (PUD) in a vulnerable segment of the population.

Nonulcer type

Most cases of chronic indigestion--as many as 65%--fall into this third category. Nonulcer dyspepsia is sometimes called functional dyspepsia because it appears to be related to abnormalities in the way that the stomach empties its contents into the intestine. In some people, the stomach empties either too slowly or too rapidly. In others, the stomach's muscular contractions are irregular and uncoordinated. These disorders of stomach movement (motility) may be caused by hypersensitive nerve endings in the stomach tissues. Patients in this group are likely to be younger than 45 and have a history of taking medications for anxiety or depression.

Diagnosis

Patient history

Because indigestion is a nonspecific set of symptoms, patients who feel sick enough to seek medical attention are likely to go to their primary care doctor. The history does not always point to an obvious diagnosis. The doctor can, however, use the process of history-taking to evaluate the patient's mood or emotional state in order to assess the possibility of a psychiatric disturbance. In addition, asking about the location, intensity, timing, and recurrence of the indigestion can help the doctor weigh the different diagnostic possibilities.

An important part of the history-taking is asking about symptoms that may indicate a serious illness. These warning symptoms include:

  • Weight loss
  • Persistent vomiting
  • Difficulty or pain in swallowing
  • Vomiting blood or passing blood in the stools
  • Anemia.

Imaging studies

If the doctor thinks that the indigestion should be investigated further, he or she will order an endoscopic examination of the stomach. An endoscope is a slender tube-shaped instrument that allows the doctor to look at the lining of the patient's stomach. If the patient has indigestion of the esophagitis type or nonulcer type, the stomach lining will appear normal. If the patient has PUD, the doctor will be able to see breaks or ulcerated areas in the tissue. He or she may also order ultrasound imaging of the abdomen, or a radionuclide scan to evaluate the motility of the stomach.

Laboratory tests

Blood tests

If the patient is over 45, the doctor will have the patient's blood analyzed for a complete blood cell count, measurements of liver enzyme levels, electrolyte and serum calcium levels, and thyroid function.

Tests for Helicobacter pylori

Doctors can now test patients for the presence of H. pylori without having to take a tissue sample from the stomach. One of these noninvasive tests is a blood test and the other is a breath test.

Treatment

Since most cases of indigestion are not caused by serious disorders, many doctors prefer to try medications and other treatment measures before ordering an endoscopy.

Diet and stress management

Many patients benefit from the doctor's reassurance that they do not have a serious or fatal disorder. Cutting out alcoholic beverages and drinks containing caffeine often helps. The patient may also be asked to keep a record of food intake, daily schedule, and symptom severity. Food diaries sometimes reveal psychologic or dietary factors that influence indigestion.

Medications

Patients with the esophagitis type of indigestion are often treated with H2 antagonists. H2 antagonists are drugs that block the secretion of stomach acid. They include ranitidine (Zantac) and famotidine (Pepcid).

Patients with motility disorders may be given prokinetic drugs. Prokinetic medications speed up the emptying of the stomach and increase intestinal motility. They include metoclopramide (Reglan) and cisapride (Propulsid). These drugs relieve symptoms in 60-80% of patients.

Removal of H. pylori

It is not clear that patients with H. pylori infections who have not developed gastric ulcers need to have the bacterium removed. Some studies indicate, however, that these patients may benefit from antibiotic therapy.

Alternative treatment

Herbal medicine

Practitioners of Chinese traditional herbal medicine might recommend medicines derived from peony (Paeonia lactiflora), hibiscus (Hibiscus sabdariffa), or hare's ear (Bupleurum chinense) to treat indigestion. Western herbalists are likely to prescribe fennel (Foeniculum vulgare), lemon balm (Melissa officinalis), or peppermint (Mentha piperita) to relieve stomach cramps and heartburn.

Homeopathy

Homeopaths tailor their remedies to the patient's overall personality profile as well as the specific symptoms. Depending on the patient's reaction to the indigestion and some of its likely causes, the homeopath might choose Gelsemium (Gelsemium sempervirens), Carbo vegetalis, Nux vomica, or Pulsatilla (Pulsatilla nigricans).

Other treatments

Some alternative treatments are aimed at lowering the patient's stress level or changing attitudes and beliefs that contribute to indigestion. These therapies and practices include Reiki, reflexology, hydrotherapy, therapeutic massage, yoga, and meditation.

Prognosis

Most cases of mild indigestion do not need medical treatment. For patients who consult a doctor and are given an endoscopic examination, 5-15% are diagnosed with GERD and 15-25% with PUD. About 1% of patients who are endoscoped have stomach cancer. Most patients with functional dyspepsia do well on either H2 antagonists or prokinetic drugs, depending on the cause of their indigestion.

Prevention

Indigestion can often be prevented by attention to one's diet, general stress level, and ways of managing stress. Specific preventive measures include:

  • Stop smoking.
  • Cutting down on or eliminating alcohol, tea, or coffee.
  • Avoiding foods that are highly spiced or loaded with fat.
  • Eating slowly and keeping mealtimes relaxed.
  • Practicing yoga or meditation.
  • Not taking aspirin or other medications on an empty stomach.
  • Keeping one's weight within normal limits.

Key Terms

Dyspepsia
Another name for indigestion.
Endoscope
A slender tubular instrument used to examine the inside of the stomach.
Gastroesophageal reflux disease (GERD)
A disorder of the lower end of the esophagus, caused by stomach acid flowing backward into the esophagus and irritating the tissues.
H antagonist
A type of drug that relieves indigestion by reducing the production of stomach acid.
Heartburn
A popular term for an uncomfortable burning sensation in the stomach and lower esophagus, sometimes caused by the reflux of small amounts of stomach acid.
A gram- negative rod-shaped bacterium that lives in the tissues of the stomach and causes inflammation of the stomach lining.
Motility
The movement or capacity for movement of an organism or body organ. Indigestion is sometimes caused by abnormal patterns in the motility of the stomach.
Peptic ulcer disease (PUD)
A stomach disorder marked by corrosion of the stomach lining due to the acid in the digestive juices.
Prokinetic
A drug that works to speed up the emptying of the stomach and the motility of the intestines.
Reflux
The backward flow of a body fluid or secretion. Indigestion is sometimes caused by the reflux of stomach acid into the esophagus.

Further Reading

For Your Information

    Other

  • Indigestion. http://www.thriveonline.com/health/Library/illsymp/illness299.html (6 April 1998).

Gale Encyclopedia of Medicine. Gale Research, 1999.

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