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翻译：王宁宁
审核：唐文瑞 陈志锦
5月5日，针对可能存在寨卡病例暴露的无症状孕妇，美国疾病预防控制中心（CDC）更新了2016年版寨卡病毒推荐指南。更新版指南采用的最新数据表明，免疫球蛋白M （IgM）对寨卡病毒的免疫反应可以持续超过12周，因此不是衡量近期感染的可靠指标。相反，寨卡病毒RNA 水平会随时间而下降，寨卡病毒核酸检测（NAT）阳性检出率也随之降低，因此阴性的NAT检测结果并不能排除近期感染。
根据美国疾病预防控制中心新闻发布，这样的改变是因为CDC之前的孕妇寨卡病毒检测指南在某种程度上太过依赖于病毒免疫球蛋白M(IgM)ELISA测试来检测体内对抗寨卡病毒感染的病毒抗体或蛋白质。而新数据表明,寨卡病毒感染,类似于其他黄病毒感染,一些人感染后，寨卡病毒抗体可能会在体内持续存在几个月。因此，这些检测的结果可能无法确定女性是在怀孕前还是怀孕后感染的。”
这个时间点非常重要，因为胎儿的最高风险与妊娠初期的寨卡病毒感染有关。
更新版指南对可能已暴露于寨卡病毒而无症状的孕妇修改了孕前检测建议，而对有寨卡病毒症状的孕妇检测的建议则保持不变。
CDC警告说,“尽管如此,如果一个有症状的孕妇IgM阳性，NAT阴性,曾居住在或者游览至CDC标签为寨卡旅游警告的区域,医疗服务提供者应该认识到IgM阳性并不一定表明近期感染。”
检测无症状孕妇的五个步骤
CDC建议检测可能暴露于寨卡病毒而无症状的孕妇在受孕之前进行五个步骤,包括那些居住在或频繁（每天或每周）前往CDC旅行警告旅游区的女性。
1、筛检所有孕妇寨卡病毒暴露风险及症状，及时对那些怀孕期间出现症状或其性伴侣寨卡病毒检测阳性的孕妇进行NAT检测。
2、至少每三个月进行一次寨卡NAT检测, 除非前一次检测结果为阳性。
3、如果因寨卡病毒以外的原因进行羊膜穿刺术,还要考虑对羊膜穿刺标本进行寨卡NAT检测。
4、每三个月告知孕妇进行寨卡病毒IgM和NAT检测的局限性。
5、考虑孕前IgM检测来确定寨卡病毒IgM基线水平，作为孕前咨询的一部分。
原文：
New Guidance Issued by CDC on Zika IgM Testing in Pregnancy
The Centers for Disease Control and Prevention (CDC) updated the 2016 Zika virus recommendations for clinicians caring for asymptomatic pregnant women with possible Zika exposure on May 5. The updated guidance incorporates new data showing that the immunoglobulin M (IgM) response to Zika can persist beyond 12 weeks, and is therefore not a reliable sign of recent infection. Conversely, Zika virus nucleic acid test (NAT) positivity fades over time as the Zika RNA level declines, so a negative NAT does not rule out recent infection.
"This change is being made because CDC's Zika testing guidance for pregnant women relies, in part, on a test [Zika virus Immunoglobulin M (IgM) ELISA] to detect Zika antibodies or proteins that the body makes to fight Zika infections," according to a CDC news release. "New data suggest that Zika virus infection, similar to some other flavivirus infections, may result in Zika antibodies staying in the body for months after infection for some individuals. As a result, results of these tests may not be able to determine whether women were infected before or after they became pregnant."
This timing is important because the highest risk to the fetus is associated with infection during the first trimester of pregnancy.
The updated guidance changes the recommendations for testing asymptomatic pregnant women who might have been exposed to Zika before conception.
Recommendations for testing pregnant women who are symptomatic for Zika remain unchanged.
"However," the CDC warns, "if a symptomatic pregnant woman is IgM positive and NAT negative, and lived in or traveled to an area with a posted CDC Zika Travel Notice, healthcare providers should recognize that the positive IgM result does not necessarily indicate recent infection."
Five Steps for Testing Asymptomatic Pregnant Women
The CDC recommends five steps for testing asymptomatic pregnant women with possible Zika exposure before conception, including women who have lived in or frequently (daily or weekly) travel to areas included in CDC travel warnings.
1. Screen all pregnant women for Zika exposure risk and symptoms, with prompt Zika NAT for those who become symptomatic during pregnancy or whose sexual partner tests positive for Zika infection.
2. Test Zika NAT at least every trimester unless a previous test was positive.
3. If amniocentesis is performed for a reason other than Zika, consider also conducting Zika NAT of the amniocentesis specimens.
4. Each trimester counsel pregnant women on the limitations of Zika IgM and NAT testing.
5. Consider preconception IgM testing to determine baseline Zika virus IgM levels as part of preconception counseling.
图文编辑：那颜
审稿：陈文森 卢先雷
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发表于 2017-6-11 22:21:07