Treating children for worms yields long-term benefits, says new study
Parasite load seems to affect negatively cognitive abilities.Decreased Parasite Load and Improved Cognitive Outcomes Caused by Deworming and Consumption of Multi-Micronutrient Fortified Biscuits in Rural Vietnamese Schoolchildren
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3144834/Parasite load explains  67% of the worldwide variation in intelligence:
"Parasite prevalence and the worldwide distribution of cognitive ability"
https://royalsocietypublishing.org/doi/abs/10.1098/rspb.2010...