Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO, USA.
Center for Global Health, Colorado School of Public Health, Aurora, CO, USA.
Glob Health Sci Pract. 2017 Dec 28;5(4):686-696. doi: 10.9745/GHSP-D-17-00116.
Congenital microcephaly is the result of a disturbance in early brain development and can have multiple etiologies. Establishing background prevalence of microcephaly in Zika virus (ZIKV)-affected areas is important for improving identification of ZIKV-affected newborns. However, to date, there is limited consistent guidance for the accurate identification of microcephaly in infants of unknown gestational age, a common concern in low- and middle-income countries.
Occipital frontal head circumference (OFC) obtained from infants (0-13 days) of unknown gestational age at enrollment in a pregnancy registry in rural Guatemala from August 2014 to March 2016 were retrospectively reviewed. Trained community health nurses recorded anthropometry in an online database. In April 2015, ZIKV was identified in this population. Gestational age was approximated in 2 ways: presumed term and estimated using z-score of zero for height on modified Fenton growth curves. After which, z-scores for OFC and weight were obtained. Microcephaly and microcephaly background prevalence were estimated using 7 established microcephaly case definitions from national and international organizations and 3 proposed definitions using Fenton growth curves. Independent associations with microcephaly and OFC, including relationship with date of birth, were assessed with prevalence ratios and linear regression.
For 296 infants, the mean OFC was 33.1 cm (range, 29.5 to 37 cm) and the mean OFC z-score was -0.68. Depending on case definition, 13 to 125 infants were classified as having microcephaly (background prevalence 439 to 4,223 per 10,000 live births), and 1 to 9 infants were classified as having severe microcephaly (<-3 standard deviation [SD]) (34 to 304 per 10,000 live births). Five (1.7%) infants met all the microcephaly case definitions. Weight ≤-1 SD (prevalence rate [PR], 3.77; 95% confidence interval [CI]: 1.6 to 8.8; =.002) and small for gestational age (PR, 4.68; 95% CI, 1.8 to 12.3; =.002) were associated with microcephaly. Date of birth was not associated with OFC z-score or OFC after adjusting for gestational age and gender.
Estimated background microcephaly is high in rural Guatemala compared with reported rates in Latin America prior to ZIKV epidemic, which has important implications for neonatal screening programs for congenital ZIKV infection. Fenton growth curves offer a standardized approach to the identification of microcephaly in infants of unknown gestational age.
先天性小头症是早期大脑发育障碍的结果，可能有多种病因。确定寨卡病毒（ZIKV）疫区小头症的背景流行率对于提高对 ZIKV 感染新生儿的识别能力非常重要。然而，迄今为止，对于未知胎龄婴儿小头症的准确识别，在中低收入国家普遍存在，缺乏一致的准确识别的指导意见。
对 2014 年 8 月至 2016 年 3 月期间在危地马拉农村妊娠登记处登记的未知胎龄的婴儿（0-13 天）的枕额径（OFC）进行回顾性审查。经过培训的社区卫生护士将人体测量学数据记录在在线数据库中。2015 年 4 月，在该人群中发现了寨卡病毒。胎龄通过以下两种方式进行估算：根据假设的足月和使用改良 Fenton 生长曲线的身高 Z 分数为 0 进行估算。之后，获得 OFC 和体重的 Z 分数。使用来自国家和国际组织的 7 种已确立的小头症病例定义以及使用 Fenton 生长曲线的 3 种建议定义来估计小头症和小头症背景流行率。使用患病率比和线性回归评估与小头症和 OFC 相关的独立关联，包括与出生日期的关系。
对于 296 名婴儿，平均 OFC 为 33.1cm（范围 29.5 至 37cm），平均 OFC Z 分数为-0.68。根据病例定义，13 至 125 名婴儿被归类为小头症（背景流行率为每 10,000 例活产儿 439 至 4,223 例），1 至 9 名婴儿被归类为严重小头症（<-3 个标准差[SD]）（每 10,000 例活产儿 34 至 304 例）。有 5 名（1.7%）婴儿符合所有小头症病例定义。体重≤-1SD（患病率[PR]，3.77；95%置信区间[CI]：1.6 至 8.8；=.002）和小于胎龄（PR，4.68；95%CI，1.8 至 12.3；=.002）与小头症相关。调整胎龄和性别后，出生日期与 OFC Z 分数或 OFC 无关。
与 ZIKV 流行前拉丁美洲报告的发病率相比，危地马拉农村地区估计的小头症背景流行率较高，这对先天性 ZIKV 感染的新生儿筛查计划具有重要意义。Fenton 生长曲线为识别未知胎龄婴儿的小头症提供了一种标准化方法。
