寨卡病毒病與新生兒小頭畸形(The relation between Zika disease and Microcephaly)

寨卡病毒病與新生兒小頭畸形的關聯性研究, 又是一個流行病學中, 病因學研究的好好例子…

在2015年5月時, 巴西的衛生部門開始監測到, 在巴西東北部地區, 出現有與登革熱類似的病症. 隨疫情的發展, 後來證實是Zika, 但同時亦發現在相同的地區, 新生兒小頭症的個案較以往明顯增多! 幾乎是2010年至2014年平均數156.2個案例的22.6倍(3530/156.2).

若按流行病學病因研究的說法: 在Miller法則上符合”共變”關係; 而病因關聯上已是符合時間順序關係.

隨著時間的推移、小頭症病例的增多、以及醫學/科研專家的重視, 紛紛出現了一些相關的研究文章, 但始終仍未見有Zika病毒感染與小頭症的關聯性分析, 如OR值或RR值、劑量效應關係等.

其中近日在The New England journal of medicine 就刊登了一篇文章: Zika Virus Infection in Pregnant Women in Rio de Janeiro — Preliminary Report. 在它的結果上:

Results

A total of 88 women were enrolled from September 2015 through February 2016; of these 88 women, 72 (82%) tested positive for ZIKV in blood, urine, or both. The timing of acute ZIKV infection ranged from 5 to 38 weeks of gestation. Predominant clinical features included pruritic descending macular or maculopapular rash, arthralgias, conjunctival injection, and headache; 28% had fever (short-term and low-grade). Women who were positive for ZIKV were more likely than those who were negative for the virus to have maculopapular rash (44% vs. 12%, P=0.02), conjunctival involvement (58% vs. 13%, P=0.002), and lymphadenopathy (40% vs. 7%, P=0.02). Fetal ultrasonography was performed in 42 ZIKV-positive women (58%) and in all ZIKV-negative women. Fetal abnormalities were detected by Doppler ultrasonography in 12 of the 42 ZIKV-positive women (29%) and in none of the 16 ZIKV-negative women. Adverse findings included fetal deaths at 36 and 38 weeks of gestation (2 fetuses), in utero growth restriction with or without microcephaly (5 fetuses), ventricular calcifications or other central nervous system (CNS) lesions (7 fetuses), and abnormal amniotic fluid volume or cerebral or umbilical artery flow (7 fetuses). To date, 8 of the 42 women in whom fetal ultrasonography was performed have delivered their babies, and the ultrasonographic findings have been confirmed.

 

由於它是一個隊列研究, 若按:

	病例	對照	總數
暴露	12	0	12
非暴露	30	16	46
總數	42	16	58

所得的RR=1.53（1.24, 1.89）, 結果解釋為: 孕婦暴露在Zika病毒, 其後出現胎兒畸形的風險, 是無暴露的孕婦1.53倍.

雖然這是病因學研究的病因關聯性分析, 但僅能證明Zika與胎兒畸形有關, 仍未能證明Zika與小頭畸形的關係…

參考文獻:

1.http://www.medpagetoday.com/InfectiousDisease/GeneralInfectiousDisease/55702

2. http://www.nejm.org/doi/full/10.1056/NEJMoa1602412

[更新2016.11.23] 
今日一國外很有名氣的醫學網站Medscape貼文, 有關寨卡病毒病的孕婦檢測指引, 據知是由美國疾控中心制作的.

http://www.medscape.com/viewarticle/871873_2?nlid=110777_804