Chagas' disease

Chagas' Disease

 

Definition

Chagas' disease is named after Dr. Carlos Chagas who first found the organism in the early 1900s. It involves damage to the nerves that control the heart, digestive and other organs, and eventually leads to damage to these organs. Worldwide, Chagas' disease affects over 15 million persons, and kills 50,000 each year. Researchers believe that the parasite that causes the disease is only found in the Americas.

Description

When a person is infected with Chagas' disease, the parasite known as Trypanosoma cruzi first causes a mild, short-lived period of "acute" illness; then after a long period without symptoms, the effects of the infection begin to appear. The heart, esophagus, and colon are most frequently involved. These organs become unable to contract properly, and begin to stretch or dilate.

Causes and symptoms

T. cruzi is carried by insects or bugs known as reduviid or "kissing bugs." These insects are very common in Central and South America where they inhabit poorly constructed houses and huts. The insects deposit their waste material, exposing inhabitants to the parasites. The parasites then enter the body by way of a cut or via the eyes or mouth. T. cruzi can also be transmitted by blood transfusion. Eating uncooked, contaminated food or breastfeeding can also transmit the disease. The reduviids, in turn, become infected with the parasite by biting infected animals and humans.

There are three phases related to infection:

• Acute phase lasts about two months, with non-specific symptoms of low grade fever, headache, fatigue, and enlarged liver or spleen.
• Indeterminate phase lasts 10-20 years, during which time no symptoms occur, but the parasites are reproducing in various organs.
• Chronic phase is the stage when symptoms related to damage of major organs (heart, esophagus, colon) begin.

In the chronic phase, irregularities of heart rhythm, heart failure, and blood clots cause weakness, fainting, and even sudden death.

Esophageal symptoms are related to difficulty with swallowing and chest pain. Because the esophagus does not empty properly, food regurgitates into the lungs causing cough, bronchitis, and repeated bouts of pneumonia. Inability to eat, weight loss, and malnutrition become a significant factor in affecting survival.

Involvement of the large intestine (colon) causes constipation, distention, and abdominal pain.

Diagnosis

The best way to diagnose acute infection is to identify the parasites in tissue or blood. Occasionally it is possible to culture the organism from infected tissue, but this process usually requires too much time to be of value. In the chronic phase, antibody levels can be measured. Efforts to develop new, more accurate tests are ongoing.

Treatment

In most cases treatment of symptoms is all that is possible. Present medications can reduce the duration and severity of an acute infection, but are only 50% effective, at best, in eliminating the organisms.

Cardiac effects are managed with pacemakers and medications. Esophageal complications require either endoscopic or surgical methods to improve esophageal emptying, similar to those used to treat the disorder known as achalasia. Constipation is treated by increasing fiber and bulk laxatives, or removal of diseased portions of the colon.

Prognosis

Those patients with gastrointestinal complications often respond to some form of treatment. Cardiac problems are more difficult to treat, particularly since transplant would rekindle infection.

Prevention

Visitors traveling to areas of known infection should avoid staying in mud, adobe, or similar huts. Mosquito nets and insect repellents are useful in helping to avoid contact with the bugs. Blood screening is not always effective in many regions where infection is common. It is necessary to carefully screen people who have emigrated from Central and South America before they make blood donations.

Key terms

Achalasia — An esophageal disease of unknown cause, in which the lower sphincter or muscle is unable to relax normally, and leads to the accumulation of material within the esophagus.

Endoscopy — Exam using an endoscope (a thin flexible tube which uses a lens or miniature camera to view various areas of the gastrointestinal tract). When the procedure is performed to examine certain organs such as the bile ducts or pancreas, the organs are not viewed directly, but rather indirectly through the injection of x ray.

Parasite — An organism that lives on or in another and takes nourishment (food and fluids) from that organism.

Regurgitation — Flow of material back up the esophagus and into the throat or lungs.

Resources

Other

Centers for Disease Control. 〈http://www.cdc.gov/nccdphp/ddt/ddthome.htm〉.

Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.

trypanosomiasis

 [tri-pan″o-so-mi´ah-sis]

infection with trypanosomes.

African trypanosomiasis an often fatal disease of Africa caused by Trypanosoma gambiense or T. rhodesiense and involving the central nervous system. The parasites are transmitted to human beings from cattle or other animals by the bite of the tsetse fly. Usually the first symptom is inflammation at the site of the bite, appearing within 48 hours. Within several weeks the parasites invade the blood and lymph, and eventually they attack the central nervous system. Characteristic symptoms include intermittent fever, rapid heartbeat, and enlargement of the lymph nodes and spleen. In the advanced stage of the disease there are personality changes, apathy, sleepiness, disturbances of speech and gait, and severe emaciation.



Pharmacologic treatment should begin as soon as possible and is based on lab results and patient symptoms. suramin, pentamidine isethionate, and melarsoprol are the most common medications used. Pentamidine isethionate or suramin may be injected to remove parasites from the blood or lymph nodes before onset of disease, but the most effective preventive measure is eradication of the tsetse fly.

American trypanosomiasis (South American trypanosomiasis) a form found from the southern United States south into South America, caused by Trypanosoma cruzi; it is transmitted to humans from wild animals by means of the feces of a blood-sucking bug. The parasites multiply around the points of entry before entering the blood and eventually attacking the heart, brain, and other tissues. Called also Chagas' disease.



The acute form often attacks children. Early symptoms include swelling of the eyelids and the development of a hard, red, painful nodule on the skin. Enlargement of the lymph nodes, liver, and spleen occurs, along with inflammation of the heart muscle, psychic changes, and general debility. In adults the chronic form often resembles heart disease.

The control strategy suggested by the World Health Organization is to interrupt transmission of the disease by the vectors and to systematically screen blood donors. Preventive measures, such as the wearing of protective clothing and the use of insecticides, are of primary importance. Medication with antiprotozoal agents is usually effective when administered during the acute stage of infection.

Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

Chagas' disease

(shä′gəs)

n.

A form of trypanosomiasis caused by the protozoan Trypanosoma cruzi, that occurs in South America and southern North America and is manifested by swelling of the skin at the site of entry and enlargement of the lymph nodes, liver, and spleen.

The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.

Chagas' disease

American trypanosomiasis Parasitology An infection caused by a protozoan, Trypanosoma cruzi, which is a major cause of M&M in Latin American Epidemiology Circa 17 x 106 have chronic CD in South America; T cruzi is transferred in the feces of hematophagous triatomine insects–kissing or reduviid bugs which may contaminate the bite itself, the conjunctiva or a mucosal surface; less common routes of transmission include blood transfusion–20,000 transfusion-related cases/yr, Brazil, maternofetal–vertical, breast milk, accidental–lab workers Clinical-acute CD Mild with 5% mortality; fever, malaise, headache, anorexia, edema of face and lower extremities, conjunctivitis, myocarditis, lymphadenopathy, hepatosplenomegaly; rarely muscle or CNS invasion; the acute phase lasts 2 to 3 months; infants may develop meningitis and heart involvement chronic CD 10-30 yrs latency; severe cardiomyopathy with biventricular enlargement, thinning of ventricular walls, mural thrombi, interstitial fibrosis, conduction defects–eg, right BBB, or complete AV block, CHF; GI disease with megaesophagus and/or megacolon due to either local denervation or possibly to an autoimmune mechanism Lab-acute Parasites in peripheral blood smear Lab-chronic Serology for IgG by ELISA, CF, indirect immunofluorescence Treatment Therapies, benzidazole, nifurtimox are inadequate; cures in 50% at high toxicity Prognosis Poor in Pts with CHF, left ventricular aneurysm or dysfunction.

McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.

Chagas' disease

South American trypanosomiasis, a disease spread by the cone-nosed or assassin reduviid bug. The organism is Trypanosma cruzi and the disease is a major cause of heart damage and HEART FAILURE in endemic areas. (Carlos Chagas, 1879–1934, Brazilian physician).

Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005