Primary School Deworming — Kenya
ICS / MIT Poverty Action Lab · Western Kenya · 1998
Summary
The Kenya deworming study found that mass treatment with a cheap, safe drug increased school participation substantially — and that the effects persisted into adulthood as higher earnings. The $3.50 cost per additional year of schooling made it one of the most cost-effective education interventions documented. The study became a cornerstone of evidence-based development and triggered a global scale-up. Subsequent reanalysis and replication have produced more modest estimates, and a Cochrane review found weaker evidence of general health benefits — but the cost-effectiveness case for deworming in high-prevalence areas remains strong.
Research question
"Does mass deworming treatment in primary schools improve attendance and learning outcomes?"
Methodology
Intervention
75 schools randomly assigned to receive deworming treatment (albendazole) annually for 2 years vs. delayed treatment control; treatment delivered through schools
Assignment
Randomized controlled trial (school-level)
Sample size
30,000+ students across 75 schools
Primary outcome
School participation; health outcomes; long-run earnings
Effect estimate
School participation: +7.5 percentage points; cost per additional year of schooling: $3.50; long-run earnings for treated cohort: +14% at age 20
Decision
Kenya national deworming program adopted; Evidence Action's Deworm the World Initiative reached 280 million children annually
Result
Positive
School participation: +7.5 percentage points; cost per additional year of schooling: $3.50; long-run earnings for treated cohort: +14% at age 20
Evidence strength
Strong
Randomized controlled trial with large sample.
Replication status
Partially replicated
Institution
ICS / MIT Poverty Action Lab
Location
Western Kenya
Year
1998
Policy area
International Development
Mechanism
Human capital