When is deworming indicated?

When is Deworming Indicated?

Deworming is indicated for confirmed parasitic infections, empirically for high-risk populations with prolonged endemic exposure (even with negative stool tests), for symptomatic patients with clinical suspicion, and as part of mass drug administration programs in endemic areas for school-age children.

Confirmed Parasitic Infections

Hookworm Infection

• Treat all confirmed hookworm infections with albendazole 400 mg orally, repeated in 2 weeks 1
• This regimen is effective against both Ancylostoma duodenale and Necator americanus 1
• The same dosing applies to both adults and children 1
• Clinical presentation includes transient itching at larval entry sites, maculopapular rash, gastrointestinal symptoms, and iron-deficiency anemia in heavy infections 1

Pinworm (Enterobiasis)

• Treat confirmed pinworm infection with either albendazole 400 mg or mebendazole 100 mg as a single dose, repeated in 2 weeks 2
• The standardized dose applies across all age groups, including children as young as 2 years 2
• Nocturnal perianal itching is the hallmark symptom, though 30-40% of infected children are asymptomatic 2
• Diagnosis is made via cellophane tape test applied to perianal skin in the morning before bathing 2
• Treat the entire household simultaneously to prevent reinfection 3

Strongyloidiasis

• Treat with ivermectin 200 mcg/kg as a single oral dose 4
• Immunocompromised patients require extended treatment: 200 mcg/kg on days 1,2,15, and 16 5
• At least three stool examinations over three months post-treatment are essential to ensure eradication, as recrudescence can occur up to 106 days after therapy 4

Other Helminth Infections

• Ascaris lumbricoides and Trichuris trichiura: Treat with mebendazole or albendazole 3
• Tapeworms (Taenia, Diphyllobothrium, Hymenolepis): Require specific antiparasitic therapy 3

Empiric Treatment Indications

Prolonged Endemic Exposure with Negative Testing

• For individuals with 6+ years residence in endemic areas, empiric treatment is warranted even with negative stool examinations 1
• Standard stool microscopy (3 samples on different days) has high false-negative rates, identifying pathogens in only 1.4% of samples in some studies 1
• Recommended empiric regimen: albendazole 400 mg plus ivermectin 200 mcg/kg as a single dose 1
• This combination covers undetected geohelminth infections and prevents serious complications like chronic hookworm anemia and strongyloidiasis 1

Travelers Returning from Endemic Areas

• Empiric treatment is recommended for travelers from high-risk areas who had barefoot contact with soil, consumed unwashed produce, or had prolonged exposure 1
• Rationale: Chronic hookworm causes insidious iron-deficiency anemia, and schistosomiasis can lead to irreversible organ damage if untreated 1
• The single-dose regimen (albendazole 400 mg + ivermectin 200 mcg/kg) is safe, highly effective, and eliminates the need for repeated low-sensitivity stool testing 1

Eosinophilia with Negative Stool Studies

• For patients with unexplained eosinophilia and negative stool microscopy, empiric treatment with albendazole 400 mg plus ivermectin 200 mcg/kg is recommended 1, 5
• This covers prepatent or undetected geohelminth infections 5
• Retreatment 1 month after symptom resolution may be needed to ensure adult worms are treated 1

Immunocompromised Patients

• Consider empiric treatment in immunocompromised patients who are ill-appearing, even without confirmed diagnosis 6
• Young infants who are ill-appearing may also warrant empiric treatment 6

Mass Drug Administration Programs

School-Based Deworming

• School-age children (5-15 years) in endemic areas should receive routine deworming 2-3 times per year 7, 8
• This population suffers the highest infection rates and worm burden due to poor sanitation and hygiene 8
• School-based programs significantly reduce infection intensity even in high-transmission environments: Ascaris intensity declined 63-97%, Trichuris 40-76%, and hookworm 35-57% compared to controls 7
• Over 400 million school-age children worldwide are infected with roundworm, whipworm, and hookworm 8

At-Risk Populations

• International students and travelers, migrant laborers, refugees, children of foreign adoptions, and homeless populations are at increased risk 3
• These groups warrant screening and empiric treatment when indicated 3

Critical Safety Considerations

Mandatory Pre-Treatment Screening

• Always exclude Loa loa infection before administering ivermectin in anyone who has traveled to Central or West African endemic regions 5, 4
• Patients with high Loa loa microfilaremia (>8,000 microfilariae/mL) risk severe adverse events including encephalitis and death with ivermectin treatment 5
• Exclude onchocerciasis before ivermectin treatment to prevent severe Mazzotti reactions 5

Medication Administration

• Ivermectin must be taken on an empty stomach with water to optimize bioavailability 5
• No dose adjustments needed for renal impairment, but safety of multiple doses in severe liver disease is not established 5
• Monitor for hepatotoxicity and leukopenia if albendazole treatment extends beyond 14 days 1, 2

Special Populations

• Ivermectin is classified as "human data suggest low risk" in pregnancy and is probably compatible with breastfeeding 5
• Children under 10 years should not receive ivermectin for scabies; permethrin cream is preferred 5
• For children aged 12-24 months with suspected hookworm, expert consultation is recommended before treatment 1

When NOT to Deworm Empirically

Acute Watery Diarrhea

• In most patients with acute watery diarrhea without recent international travel, empiric antimicrobial therapy is NOT recommended 6
• Exceptions: immunocompromised patients or young infants who are ill-appearing 6
• Avoid empiric treatment in persistent watery diarrhea lasting ≥14 days 6

Asymptomatic Contacts

• Asymptomatic contacts of people with diarrhea should NOT receive empiric treatment 6
• Instead, advise appropriate infection prevention and control measures 6

Follow-Up and Monitoring

Post-Treatment Assessment

• If symptoms persist after treatment, repeat stool examination 2-3 weeks post-treatment 1
• For strongyloidiasis, perform at least three stool examinations over three months using concentration techniques (Baermann apparatus) 4
• Treatment failure is rare; persistent symptoms usually indicate reinfection rather than drug resistance 2

Prevention of Reinfection

• Hand hygiene and wearing shoes in endemic areas are essential preventive measures 1
• Screen and treat household contacts in endemic settings 1
• Drug therapy alone is only a short-term measure; improved sanitation, hygiene education, and repeated deworming are needed to prevent reinfection 8