This is a link post to http://emiguel.econ.berkeley.edu/research/twenty-year-economic-impacts-of-deworming

Hamory, Joan, Edward Miguel, Michael Walker, Michael Kremer, and Sarah Baird. (2020). "Twenty Year Economic Impacts of Deworming", unpublished working paper.

This study exploits a randomized school health intervention that provided deworming treatment to Kenyan children and utilizes longitudinal data to estimate impacts on economic outcomes up to 20 years later. The effective respondent tracking rate was 84%. Individuals who received 2 to 3 additional years of childhood deworming experience an increase of 14% in consumption expenditure, 13% in hourly earnings, 9% in non-agricultural work hours, and are 9% more likely to live in urban areas. Most effects are concentrated among males and older individuals. Given deworming's low cost, a conservative annualized social internal rate of return estimate is 37%.

See also https://www.metaculus.com/questions/4919/who-will-win-the-worm-wars/#comment-37118