Impact of asymptomatic malaria parasitaemia on cognitive function and school achievement of schoolchildren in the Yemen Republic

Asymptomatic malaria parasitaemia is prevalent among schoolchildren in many countries. The relationship between asymptomatic parasitaemia and children 's cognitive functions was examined in a case control study and then in a n atural experiment. A group (n = 445) of asymptomatic parasitaemic boys were compared with a group of non-parasitaemic boys (n = 142) matched for grade and school on their performance on a battery of cognitive tests. Two weeks later the parasitaemic children were re-screened and 150 children of those who remained parasitaemic were matched for grade and school with 150 child ren who were no longer parasitaemic. These children were then re-tested and their cognitive function compared. Initially, after controlling for age, s ocio-economic background and nutritional status the parasitemic children pe rformed worse than the non-parasitaemic children in fine motor function tes ts. There was no difference in change in cognitive rest scores between thos e who became non-parasitaemic and those who remained parasitaemic. However, children who initially had the highest parasite density improved the most in 2 fine motor tests and a picture memory test. We were unable to show a b enefit from losing parasitaemia over a 2 week period, but it remains possib le that parasitaemia may affect cognition and longer term trials should be conducted.