Intestinal Protozoal Diseases Treatment & Management
- Author: Enrique Chacon-Cruz, MD; Chief Editor: Russell W Steele, MD more...
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- The most important aspect of providing care for children with diarrhea caused by intestinal protozoa includes standard pediatric assessments.
- Evaluate the child for signs of dehydration, including tachycardia, delayed capillary refill, decreased tears, decreased activity, decreased urine output, and altered mental status.
- Hypovolemic shock rarely occurs with these infections but must be recognized.
- The child must be evaluated for the adequacy of the nutritional status. This is particularly important in cases of chronic diarrhea and possible immunodeficiency.
- Weight must be measured and compared on the growth curve. Appropriate interventions occur following this immediate assessment.
- Oral rehydration therapy (ORT) is the preferred approach for children with mild-to-moderate dehydration. Intravenous rehydration should rarely be necessary. Current recommendations for pediatric rehydration are outlined best in The Management of Acute Diarrhea in Children: Oral Rehydration, Maintenance, and Nutritional Therapy.
- Following immediate fluid resuscitation for dehydration, the clinician must address potential nutritional issues and provide adequate nutrition to the child with acute or chronic diarrhea.
- Protozoal GI infections in immunocompetent patients are usually mild-to-moderate self-limited diseases, and special precautions are not needed.
- The hallmark for treatment of these diseases is specific antiprotozoal therapy.
- Patients with severe amebic or balantidic colitis should not receive oral nutrition and should be monitored for potential surgical complications.
- Consider parenteral nutrition in some patients.
- Patients with amebic liver abscess should be treated in the hospital until potential complications have been ruled out.
Only 2 well-recognized conditions in which surgical therapy is necessary for intestinal protozoal diseases are known: necrotizing colitis, caused by E histolytica or B coli, and complicated amebic liver abscess.
- Indications for surgery in fulminant amebic colitis include the following:
- Failure to respond to antiamebic drugs following perforation and localized abscess formation
- Persistence of abdominal distension and tenderness despite effective antiamebic therapy
- Toxic megacolon
- Partial colectomy with colostomy is recommended over primary anastomosis for localized colonic disease because an anastomosis may be incompetent because of the friable condition of the affected intestinal wall.
- For extensive disease, better surgical results have been obtained with total colectomy with exteriorization of the proximal and distal ends.
- Indications for needle aspiration in amebic liver abscess include the following:
- Rupture to pleura, pericardium, or both
- Left lobe abscesses and proximity to the pericardium
- As a diagnostic procedure when a pyogenic abscess is highly suspected
- When surgical drainage is indicated because of imminent rupture of the abscess to the peritoneal cavity or presence of necrotizing colitis
- When, in some cases, perianal fistulization of intestinal amebic foci is present and necessitates surgical drainage
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- The primary care physician can manage the vast majority of cases of gastroenteritis associated with protozoal infections. These infections rarely result in complications requiring hospitalization.
- In patients with chronic diarrhea or amebic liver abscess, consultation with a gastroenterologist along with an infectious-disease specialist may be useful.
- Surgeons should be consulted when the patient is suspected to have necrotizing colitis, complicated amebic liver abscess, or both.
- Nutritional support may also be beneficial in severe cases.
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- In immunocompetent patients, effective antiprotozoal therapy results in full recovery.
- Some patients with severe giardiasis may experience disaccharidase deficiency and may require lactose-free diets, but this is a temporary condition that usually does not last more than 2 weeks.
- Patients with AIDS and severe spore-forming protozoal infections (chronic diarrhea with wasting syndrome) require hypercaloric diets. This is indicated for the protozoal illness in addition to the wasting syndrome associated with the underlying disease.
- For amebic liver abscess, some experts recommend a low-fat diet during antiamebic treatment, but no clinical trials have examined the effects of this diet on the patient's outcome.
See the list below:
- The only limitations for physical activity are in patients with amebic liver abscess who may require hospitalization and patients who require surgery for necrotizing colitis.
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|Name||Mode of Transmission||Symptoms|
|G lamblia||Contaminated water, fecal-oral||Nausea, bloating, gas, diarrhea, anorexia|
|Dientamoeba fragilis||Fecal-oral, associated with Enterobius||Previously thought commensal; may cause diarrhea, abdominal, pain, nausea|
|Entamoeba histolytica||Contaminated water, fecal-oral, contaminated food||Colitis, dysentery, diarrhea, liver abscess, other extraintestinal disease|
|Cryptosporidium parvum||Contaminated water, swimming pools, fecal-oral||Immunocompetent patients: Self-limited diarrhea Immunosuppressed patients: Severe and interminable diarrhea|
|Isospora belli||Fecal-oral||Same as in Cryptosporidium|
|Cyclospora cayetanensis||Fecal-oral, contaminated water and food||Same as in Cryptosporidium|
|Microsporidia (Septata intestinalis, Enterocytozoon bieneusi)||Fecal-oral, contaminated water||Same as in Cryptosporidium|
|Balantidium coli||Fecal-oral (frequently associated with pigs)||Colitis, diarrhea|
|Blastocystis hominis||Fecal-oral||May cause mild diarrhea|
|Organism||Size (mm)||Stain Used||Other Tests|
|E histolytica||Trophozoite: 10-60|
|Wet mount,* trichrome, periodic Schiff||Enzyme-linked immunosorbent assay (ELISA)|
|G lamblia||Trophozoite: 9-21|
|Wet mount,* trichrome, hematoxylin, Lugol||ELISA*|
|C parvum||2-5||Modified acid-fast,* auramine-rhodamine, Sheafer method||ELISA*|
|I belli||30x12||Wet mount,* modified acid-fast*||None|
|C cayetanensis||8-10||Modified acid-fast,* wet mount||Electron microscopy|
|Microsporidia||1-2||Modified trichrome*||Electron microscopy, fluorescence methods, small intestine biopsy|
|D fragilis||7-12||Iron hematoxylin,* trichrome*||None|
|B. coli||50-200||Wet mount,* concentration techniques||None|
|B hominis||5-30||Trichrome,* iron hematoxylin*||None|
|*Preferred screening test in clinical settings.|
|Organism||Drugs, Pediatric Dose, and Treatment Duration|
|E histolytica (Luminal disease or colonization)||Iodoquinol: 40 mg/kg/d PO divided tid for 20 d; not to exceed 2 g/d|
|Paromomycin: 25-30 mg/kg/d PO divided tid for 7 d|
|E histolytica (Moderate colitis)||Metronidazole: 50 mg/kg/d PO divided tid for 10 d|
|Tinidazole: 50 mg/kg/d PO for 3 d; not to exceed 2 g/d|
|E histolytica (Severe colitis or liver abscess)||Metronidazole: 50 mg/kg/d PO divided tid for 10 d|
|Dehydroemetine*: 1-1.5 mg/kg/d divided bid PO for 5 d|
|Tinidazole†: 50 mg/kg/d PO for 3-5 d; not to exceed 2 g/d|
|G lamblia||Metronidazole: 15-20 mg/kg/d PO divided tid for 5|
|Tinidazole: 50 mg/kg/d PO once; not to exceed 2 g/dose|
|Quinacrine‡: 6 mg/kg/d PO divided tid for 5 d; not to exceed 300 mg/d|
|Furazolidone: 6 mg/kg/d PO divided qid for 7-10 d|
|Paromomycin: 40 mg/kg/d PO divided tid for 7 d|
|Nitazoxanide: 200-400 mg/d PO divided bid for 3 d|
|D fragilis||Iodoquinol: 50 mg/kg/d PO divided tid for 20 d; not to exceed 2 g/d|
|Paromomycin: 30 mg/kg/d PO divided tid for 7 d|
|Tetracycline: 40 mg/kg/d PO divided qid for 10 d; not to exceed 2 g/d|
|C parvum§||Paromomycin*: 30 mg/kg/d PO divided tid (duration unknown)|
|Nitazoxanide: 200-400 mg/d PO divided bid for 3 d|
|I belli||Trimethoprim/sulfamethoxazole (TMP/SMZ): 20/100 mg/kg/d PO divided bid for 10 d, followed by 10/50 mg/kg/d PO divided bid for 21 d|
|C cayetanensis||TMP/SMZ: 10/50 mg/kg/d PO divided bid for 3 d|
|Microsporidia S intestinalis||Albendazole* (adult dose): 800 mg/d PO divided bid|
|Microsporidia E bieneusi||No treatment recommended; albendazole may decrease the number of organisms|
|B coli||Tetracycline: 40 mg/kg/d PO divided qid for 10 d; not to exceed 2 g/d|
|Metronidazole: 35-50 mg/kg/d PO divided tid for 5 d|
|Iodoquinol: 40 mg/kg/d PO divided tid for 20 d|
|B hominis||Metronidazole: 35-50 mg/kg/d PO divided tid for 10 d|
|Iodoquinol: 40 mg/kg/d PO divided tid for 20 d|
|Nitazoxanide||: 500 mg/d PO divided bid for 3 d|
|*Efficacy is unknown.|
†Drug is available from the CDC Drug Service (phone: 404-639-3670; evenings, weekends, and holidays: 404-639-2888).
‡ Drug is not available in the United States.
§Recommended regimens are indicated only in patients who are immunosuppressed. A recent meta-analysis has not shown evidence for a reduction in the duration or frequency of diarrhea by nitazoxanide or paromomycin when compared with placebo in immunosuppressed patients, nevertheless, oocyst clearance was significantly reduced.
||Recent studies have shown effective outcomes when compared to placebo, but no clinical trials have compared with other antiparasitic drugs.