Research on the mother-to-infant transmission of hepatitis C virus

近年来，在日本，丙型肝炎病毒（HCV）感染的主要途径是输血。这种病毒的母婴传播被怀疑是自然感染的最重要途径之一，但其频率和影响这种感染的因素尚不清楚。由于携带者状态即使在成年人感染HCV时也会发展，这在B型肝炎病毒中是罕见的，因此对HCV携带者家庭的回顾性研究不能阐明上述问题。在本研究中，我们进行了一项前瞻性的随访研究，所生的婴儿的HCV携带者的母亲发现的筛查孕妇，在日本的六个不同地区的孕妇进行了筛查的血清抗体的HCV（第二代，抗-HCV），如果它是阳性的血清HCV RNA进行了检查，使用聚合酶链反应。0.45抗-HCV阳性率为1%~ 1.5%（平均1%），抗-HCV阳性者血清HCVRNA阳性率为71%~ 76%。对HCVRNA阳性孕妇所生婴儿进行1 ~ 3个月随访，观察其血清抗-HCV、HCVRNA及转氨酶水平。到目前为止，174名婴儿在出生后被跟踪了六个月以上，其中3.4%为慢性HCV携带者，7例为6月龄前的一过性HCV感染者。（2）大多数母亲血清转氨酶水平明显升高，但（3）HCV基因型之间感染率无差异，（4）母乳喂养与人工喂养婴儿感染率无差异。

The major route of infection by hepatitis C virus(HCV) has been blood transfusion in recent years in Japan. Mother-to-infant transmission of this virus is suspected as one of the most important routes of natural infection, but its frequency nor factors affecting this infection are not known. Since the carrier status develops even when adults are infected by HCV, which is rare by hepatitis B virus, the retrospective study of the families of HCV carriers cannot elucidate the above mentioned problems. In this research we conducted a prospective follow-up study of the infants born to the HCV carrier mothers found by screening of pregnant women.Pregnant women in six different districts of Japan were screened for serum antibody for HCV (second generation, anti-HCV) and if it was positive the serum HCV RNA was examined using polymerase chain reaction. 0.45 to 1.5% (mean 1%) of the pregnant women were positive for anti-HCV, and 71 to 76% of anti-HCV positive women were also positive for serum HCV RNA.Infants born to HCV RNA positive pregnant women were followed after birth with intervals of one to three months for more than one year after birth, examining their sera foranti-HCV, HCV RNA, as well as transaminase levels. Until now 174 infants had been followed for more than six months after birth, and six (3.4%) of them developed chronic HCV carrier status, and seven other infants showed transient infection by HCV before six months of age.Close evaluation of various factors regarding mother-to-infant infection disclosed that 1) the mothers of HCV infected infants showed higher serum HCV RNA level, and 2) most of these mothers showed apparent elevation of serum transaminase levels, but 3) no difference of infection rate was found between HCV genotypes, nor 4) between breast-fed and bottle-fed infants.