When should stool examination (fecalysis) be performed before and after albendazole treatment for Ascaris lumbricoides infection, including timing for infants and young children?

When to Perform Stool Examination (Fecalysis) for Ascaris lumbricoides

Perform stool examination before treatment to confirm Ascaris infection, and repeat at 4 weeks post-treatment to assess parasitological cure; for infants and young children under 24 months, obtain expert consultation before initiating albendazole therapy. 1, 2

Pre-Treatment Stool Examination

• Always obtain stool examination before initiating albendazole to confirm the presence of Ascaris lumbricoides eggs and establish baseline infection intensity 2, 3
• Use quantitative microscopy techniques (such as Kato-Katz) to determine egg counts per gram, which helps assess infection severity and predict treatment response 3, 4
• Pre-treatment stool examination is particularly critical in children 12-24 months of age, as albendazole use in this age group requires expert consultation and documented parasitological confirmation 1, 2

Post-Treatment Stool Examination Timing

• Perform follow-up stool examination at 4 weeks (28 days) after albendazole administration to assess parasitological cure, as albendazole acts slowly against Ascaris and eggs may persist for several weeks 3, 5
• A second follow-up examination at 8 weeks post-treatment is recommended if cure is not achieved at 4 weeks, as this timing captures any residual eggs or treatment failures requiring re-treatment 2, 4
• Studies examining stool at 10 days post-treatment showed incomplete clearance, with optimal assessment occurring between 14-60 days after treatment 3, 5

Age-Specific Considerations

Children ≥24 Months

• Standard single-dose albendazole 400 mg achieves approximately 93% parasitological cure rates 2, 5
• Routine 4-week post-treatment stool examination is sufficient for most cases 2, 5

Infants and Children 12-24 Months

• Do not administer albendazole without pre-treatment stool confirmation and expert consultation 1, 2
• More vigilant post-treatment monitoring at both 4 and 8 weeks is advisable given limited safety data in this age group 1

Infants <12 Months

• Albendazole is not recommended; stool examination should guide alternative management strategies under specialist supervision 1

Treatment Failure and Reinfection Assessment

• If stool remains positive at 4 weeks, consider repeat single-dose albendazole and re-examine at 8 weeks, as cure rates for Ascaris range from 70-98% depending on local drug efficacy 4, 6
• High reinfection rates (18.3% at 8 weeks post-cure) occur in endemic areas, making it essential to distinguish treatment failure from new infection 4
• Co-infection with Trichuris trichiura significantly reduces Ascaris cure rates (36.6% vs 69.6% for Ascaris alone) and increases reinfection risk, warranting closer follow-up 4

Common Pitfalls to Avoid

• Do not assess cure before 4 weeks, as albendazole acts slowly and early stool examination may show persistent eggs despite eventual cure 3
• Do not rely on single stool specimens, as sensitivity improves with multiple samples examined over several days 3
• Avoid empirical treatment without stool confirmation in children under 24 months, as the risk-benefit ratio requires documented infection 1, 2
• Be aware that cure rates vary geographically (ranging from 70-98%), with some regions showing reduced albendazole efficacy requiring alternative regimens 4, 6, 7