Department of Nutrition, Harvard School of Public Health, Boston, Massachussetts, United States of America.
PLoS Negl Trop Dis. 2012;6(5):e1634. doi: 10.1371/journal.pntd.0001634. Epub 2012 May 1.
To determine whether treatment of intestinal parasitic infections improves cognitive function in school-aged children, we examined changes in cognitive testscores over 18 months in relation to: (i) treatment-related Schistosoma japonicum intensity decline, (ii) spontaneous reduction of single soil-transmitted helminth (STH) species, and (iii) ≥2 STH infections among 253 S. japonicum-infected children.
Helminth infections were assessed at baseline and quarterly by the Kato-Katz method. S. japonicum infection was treated at baseline using praziquantel. An intensity-based indicator of lower vs. no change/higher infection was defined separately for each helminth species and joint intensity declines of ≥2 STH species. In addition, S. japonicum infection-free duration was defined in four categories based on time of schistosome re-infection: >18 (i.e. cured), >12 to ≤18, 6 to ≤12 and ≤6 (persistently infected) months. There was no baseline treatment for STHs but their intensity varied possibly due to spontaneous infection clearance/acquisition. Four cognitive tests were administered at baseline, 6, 12, and 18 months following S. japonicum treatment: learning and memory domains of Wide Range Assessment of Memory and Learning (WRAML), verbal fluency (VF), and Philippine nonverbal intelligence test (PNIT). Linear regression models were used to relate changes in respective infections to test performance with adjustment for sociodemographic confounders and coincident helminth infections.
Children cured (β = 5.8; P = 0.02) and those schistosome-free for >12 months (β = 1.5; P = 0.03) scored higher in WRAML memory and VF tests compared to persistently infected children independent of STH infections. A decline vs. no change/increase of any individual STH species (β:11.5-14.5; all P<0.01) and the joint decline of ≥2 STH (β = 13.1; P = 0.01) species were associated with higher scores in WRAML learning test independent of schistosome infection. Hookworm and Trichuris trichiura declines were independently associated with improvements in WRAML memory scores as was the joint decline in ≥2 STH species. Baseline coinfection by ≥2 STH species was associated with low PNIT scores (β = -1.9; P = 0.04).
CONCLUSION/SIGNIFICANCE: Children cured/S. japonicum-free for >12 months post-treatment and those who experienced declines of ≥2 STH species scored higher in three of four cognitive tests. Our result suggests that sustained deworming and simultaneous control for schistosome and STH infections could improve children's ability to take advantage of educational opportunities in helminth-endemic regions.
为了确定治疗肠道寄生虫感染是否能改善学龄儿童的认知功能，我们研究了在 18 个月内认知测试分数的变化与以下因素的关系：（i）与日本血吸虫强度下降相关的治疗相关变化，（ii）单一土壤传播性蠕虫（STH）物种的自发减少，以及（iii）253 名日本血吸虫感染儿童中至少有 2 种 STH 感染。
采用加藤厚涂片法在基线和每季度评估寄生虫感染情况。在基线时使用吡喹酮治疗日本血吸虫感染。为每个蠕虫物种分别定义了较低 vs. 无变化/较高感染的基于强度的指标，以及≥2 种 STH 物种的联合强度下降。此外，根据血吸虫再感染时间，将日本血吸虫感染的无持续时间定义为四个类别：>18 个月（即治愈）、>12 至≤18 个月、6 至≤12 个月和≤6 个月（持续感染）。基线时没有针对 STH 的治疗，但由于可能出现自发感染清除/获得，其强度可能会发生变化。在日本血吸虫治疗后 6、12 和 18 个月时，进行了四项认知测试：广泛记忆与学习评估（WRAML）的学习和记忆领域、言语流畅性（VF）和菲律宾非言语智力测验（PNIT）。使用线性回归模型将各自感染的变化与测试表现相关联，同时调整社会人口统计学混杂因素和并发寄生虫感染。
与持续感染的儿童相比，治愈（β=5.8；P=0.02）和日本血吸虫无感染时间>12 个月（β=1.5；P=0.03）的儿童在 WRAML 记忆和 VF 测试中的得分更高，独立于 STH 感染。任何单个 STH 物种的下降（β：11.5-14.5；所有 P<0.01）和≥2 种 STH 物种的联合下降（β=13.1；P=0.01）与 WRAML 学习测试中的较高分数独立相关。钩虫和鞭虫下降与 WRAML 记忆评分的改善独立相关，≥2 种 STH 物种的联合下降也是如此。基线时≥2 种 STH 物种的共同感染与较低的 PNIT 评分相关（β=-1.9；P=0.04）。
结论/意义：治疗后治愈/日本血吸虫无感染时间>12 个月的儿童和经历≥2 种 STH 物种下降的儿童在四项认知测试中的三项测试中得分更高。我们的结果表明，持续驱虫和同时控制血吸虫和 STH 感染可以提高儿童在寄生虫感染地区接受教育机会的能力。
