Michael S Wong

Iron status of schoolchildren with varying intensities of Trichuris trichiura infection.

The relationship between varying intensities of Trichuris trichiura infection and iron status was examined in Jamaican schoolchildren, aged 7 to 11 years. A total of 409 children was identified with T. trichiura (epg > 1200). A control group comprised 207 uninfected children who were matched by school and class to every pair of infected subjects. Blood samples were obtained from 421 children: 264 infected and 157 controls. Compared to the rest of the children, those with heavy infections (epg > 10,000) had significantly lower (P < 0.05) Hb (11.5 +/- 1.3 vs. 12.1 +/- 1.1 g/dl), MCV (78.6 +/- 6.3 vs. 81.2 +/- 5.5 fl), MCH (26.2 +/- 2.9 vs. 27.5 +/- 2.5 pg) and MCHC (33.2 +/- 1.5 vs. 33.9 +/- 1.4 g/dl). Similarly, the prevalence of anaemia (Hb < 11.0 g/dl) amongst heavily infected children (33%) was significantly higher (P < 0.05) than the rest of the sample (11%). These differences remained significant after controlling for confounding variables including socio-economic status, age, gender, area of residence and the presence of Ascaris infections. Differences in red cell count, ferritin, and free erythrocyte protoporphyrin were not statistically significant and showed no association with the infectious load. These results suggest that in the Jamaican children studied, iron deficiency anemia is associated with Trichuris infections over 10,000 epg, but not with less intense infections.

School performance, nutritional status and trichuriasis in Jamaican schoolchildren

Severe infections by the geohelminth Trichuris trichiura detrimentally affect young childrens growth and development. There is concern that mild to moderate infections may affect older childrens school performance and nutritional status. We therefore examined the relationship between varying intensities of infection and school achievement, attendance and nutritional status in 616 schoolchildren. A total of 409 children with Trichuris infection of intensities greater than 1200 eggs per gram of stool (epg) were first identified, then for every 2 infected children in a class, an uninfected child was selected. After controlling for socioeconomic status, gender, age, school and the presence of Ascaris infections, the uninfected children had higher reading and arithmetic scores than children with infections of more than 4000 epg and were taller than those with intensities greater than 2000 epg. However, there were no significant differences in spelling, school attendance and body mass index. Although a treatment trial is needed to determine causation, these results indicate that moderate levels of infection are associated with poor school achievement and growth.

Trichuris trichiura infection and cognition in children : results of a randomized clinical trial

The effects of mild to moderate infections of Trichuris trichiura on cognitive functions were investigated in Jamaican children aged 7 to 10 years. In all, 189 infected children and 100 uninfected classmates were studied. The infected children were randomly assigned to receive treatment (albendazole) or a placebo. All children were given cognitive tests on enrolment and 14 weeks later. These included verbal fluency (generation of ideas), digit span (working memory), number choice (speed of processing of visual stimuli), visual search (sustained attention) and a French Vocabulary test (paired-associate learning). At baseline, the infected children had lower scores than the uninfected ones in fluency (P = 0.01), search (P = 0.02) and French (P = 0.01). Treatment effects were examined among infected children and there was no significant treatment effect for any of the tests. However, there was a significant treatment by weight-for-age interaction in fluency (P < 0.05). The children with low weight-for-age (Z-score < -1) improved with treatment while there was no improvement with treatment among the other children. We concluded that treatment of children with mild to moderate T. trichiura infections using albendazole produces little benefit in cognition if they are adequately nourished; however, undernourished children are more likely to benefit.