Trichuris trichiura infection and cognitive function in Jamaican school children.

Trichuris trichiura is extremely prevalent worldwide and there is concern that this geohelminth may affect the cognitive function of children in developing countries. A random-controlled, double-blind, treatment trial was conducted in Jamaican children with light to moderate infections. This was part of a research programme involving several studies in Jamaica. Ninety-seven subjects, each with a minimum of 1200 T. trichiura eggs/g faeces, were randomly assigned to placebo (N = 48) or treatment (N = 49) groups. Each pair of infected children was matched with an uninfected classmate (N = 48). All children were given seven cognitive function tests: French-learning; digit spans (forwards and backwards), Corsi block span; fluency; picture search; and silly sentences. Albendazole was given to the treatment group and the other groups received a placebo. Three months later, these treatments were repeated, and the cognitive function battery was given again. On pre-test, the infected groups performed significantly poorer only in the silly-sentence test (analysis of variance F-value = 8.17; two degrees of freedom; P < 0.001). There was no significant improvement with treatment in any of the tests. Taking into account these findings and those of the other Jamaican studies, it is therefore probable that light to moderate Trichuris infections have little effect on cognitive functioning in school children who have adequate nutritional status.