What are the signs and treatment of intestinal parasites in pediatric patients?

Signs and Symptoms of Intestinal Parasites in Children

Children with intestinal parasites most commonly present with persistent watery diarrhea (often nonbloody), abdominal cramps, bloating, weight loss or failure to thrive, and in some cases fever and vomiting that initially mimics viral gastroenteritis. 1, 2

Key Clinical Presentations by Parasite Type

Protozoal Infections

Giardia lamblia:

• Watery, nonbloody diarrhea that distinguishes it from bacterial dysentery 2
• Abdominal cramps, bloating, and malabsorption 2
• Weight loss or failure to thrive with chronic infection 2
• Many infected children remain completely asymptomatic 2

Cryptosporidium:

• Frequent, watery, nonbloody diarrhea persisting beyond typical viral gastroenteritis (>3-7 days) 1
• Abdominal cramps, fatigue, vomiting, anorexia, and weight loss 1
• Fever and vomiting are relatively common, initially mimicking viral gastroenteritis 1

Helminthic Infections

Pinworm (Enterobius vermicularis):

• Perianal irritation and sleep disturbances 3
• Often asymptomatic but can cause significant discomfort 3

Roundworm (Ascaris lumbricoides):

• History of passing worms by mouth or anus in approximately 50% of cases 4
• Can cause intestinal obstruction with severe abdominal pain, fever, dehydration, vomiting, and abdominal distension in acute presentations 4
• Plain abdominal radiographs may show a "whirlpool" pattern of intraluminal worms 4

Hookworm (Ancylostoma duodenale, Necator americanus):

• Blood loss leading to anemia 3
• Pica and wasting 3
• Particularly critical in young children due to anemia risk 5

Whipworm (Trichuris trichiura):

• Diarrhea and abdominal symptoms 5
• May require combination therapy for heavy infections 5

High-Risk Populations Requiring Heightened Suspicion

• Immunocompromised children (HIV-infected, solid organ transplant recipients) are at increased risk of chronic severe diarrhea leading to malnutrition, failure to thrive, severe dehydration, and death 1
• Malnourished children with persistent diarrhea 1
• Children with childcare center attendance 1
• Children with exposure to contaminated drinking water or public swimming pools 1
• Children with recent travel to developing countries 1

Diagnostic Approach

Submit at least 3 stool samples on alternate days for ova and parasites, as parasites shed intermittently and a single sample is insufficient 5, 6

Request specific testing for Cryptosporidium and Giardia, as these may not be included in routine stool studies 1, 5

Preferred diagnostic methods:

• Enzyme immunoassay or fluorescent antibody staining over acid-fast staining for enhanced sensitivity 1
• Direct microscopic examination, formol-ethyl acetate concentration, and special staining techniques 7
• Real-time PCR for Blastocystis and Dientamoeba fragilis when available 7
• Cellophane tape test for pinworm diagnosis 3

Treatment Recommendations

Helminthic Infections

First-line for common intestinal worms:

• Albendazole 400 mg single oral dose OR mebendazole 100 mg twice daily for 3 days 5
• For hookworm: albendazole 400 mg daily for 3 days (critical due to anemia risk) 5
• For whipworm: mebendazole 100 mg twice daily PLUS ivermectin 200 μg/kg once daily for 3 days (combination improves cure rates in heavy infections) 5
• For pinworm: albendazole 400 mg single dose OR mebendazole 100 mg single dose 5
• For tapeworms: praziquantel 10 mg/kg single dose for Taenia saginata/solium; 25 mg/kg single dose for Hymenolepis nana 5

Protozoal Infections

Giardia lamblia:

• Nitazoxanide 100 mg twice daily for children 1-3 years; 200 mg twice daily for children 4-11 years for 3 days (88% clinical response in HIV-uninfected children) 5
• Alternative: metronidazole 3

Cryptosporidium:

• Nitazoxanide at age-appropriate dosing for 3 days 5
• Supportive care and hydration are essential 5
• Well-tolerated with no serious adverse effects in pediatric studies 5

Critical Management Principles

Treat all confirmed infections, even in asymptomatic children, to prevent transmission and complications 5

Repeat stool examination 2-3 weeks after treatment if symptoms persist 5

Emphasize hand and fingernail hygiene with soap and adequate hydration, especially with diarrheal symptoms, to prevent reinfection 5

Common Pitfalls to Avoid

• Never use single-dose mebendazole for whipworm—it requires combination therapy with ivermectin for adequate cure rates 5
• Never overlook neurocysticercosis screening when Taenia solium is identified or species is uncertain 5
• Never rely on a single stool sample for parasites with intermittent shedding 5
• Avoid antimotility agents in young children with protozoal diarrhea due to safety concerns 5
• Consider surgical intervention for acute intestinal obstruction from Ascaris, particularly in endemic areas with economically deprived children presenting with severe symptoms 4