Medical Care
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. [24]
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.
Surgical Care
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.
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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
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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.
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For extensive disease, better surgical results have been obtained with total colectomy with exteriorization of the proximal and distal ends.
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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
Consultations
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.
Diet and Activity
Diet
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.
Activity
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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This micrograph stained with chlorazol black, revealed an Entamoeba histolytica cyst.
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This is a scanning electron micrograph (SEM) of an in vitro Giardia lamblia culture. This photograph contains both trophozoites and a cluster of maturing cysts (bottom right). At far left, the 2 trophozoite-staged organisms are positionally situated opposite to one another, with the farthest left G lamblia displaying its dorsal, or upper surface, and the protozoan to its immediate right, its ventral, or bottom surface.
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This photomicrograph revealed the morphologic details of Cryptosporidium parvum oocysts.
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This is an illustration of the life cycle of Isospora belli, the causal agent of isosporiasis.
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This photomicrograph of a fresh stool sample, which had been prepared using a 10% formalin solution, and stained with safranin, revealed the presence of 3 uniformly stained Cyclospora cayetanensis oocysts in the field of view.
Tables
Name |
Mode of Transmission |
Symptoms |
Flagellates |
|
|
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 |
Amebas |
|
|
Entamoeba histolytica |
Contaminated water, fecal-oral, contaminated food |
Colitis, dysentery, diarrhea, liver abscess, other extraintestinal disease |
Spore-forming (Coccidia) |
|
|
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 |
Ciliates |
|
|
Balantidium coli |
Fecal-oral (frequently associated with pigs) |
Colitis, diarrhea |
Other |
|
|
Blastocystis hominis |
Fecal-oral |
May cause mild diarrhea |
Organism |
Size (mm) |
Stain Used |
Other Tests |
E histolytica |
Trophozoite: 10-60 Cyst: 10-20 |
Wet mount,* trichrome, periodic Schiff |
Enzyme-linked immunosorbent assay (ELISA) |
G lamblia |
Trophozoite: 9-21 Cyst: 7-12 |
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 |
Tinidazole: 50 mg/kg/d PO once; not to exceed 2 g/dose |
Metronidazole: 15-20 mg/kg/d PO divided tid for 5 |
|
Albendazole: 15 mg/k/d (not exceed 400 mg) PO q24 h, for 5-7 days |
|
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. [25] ||Recent studies have shown effective outcomes when compared to placebo, but no clinical trials have compared with other antiparasitic drugs. |
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