Serological studies on mother-to-child transmission and virulence as an opportunistic pathogen of human herpesvirus-6 (HHV-6)

分析了47例经血清学证实的人疱疹病毒-6 （HHV-6）感染的临床表现。ES发病年龄集中在6 ~ 9月龄，6月龄为发病高峰。在我们的血清流行病学研究中，母源HHV-6抗体在同一时期消失。47例患者中。3例患儿出生后2个月内发生ES发作，所有患儿母亲血清均呈阳性。这些结果提示ES的发病年龄是由母体HHV-6抗体的消失决定的。发病年龄与喂奶方式（奶瓶和混合喂奶）无相关性。对在新生儿重症监护病房（NICU）住院超过1年的婴儿及其母亲进行HHV-6抗体检测。所有母亲HHV-6血清阳性，6名婴儿中有5名HHV-6血清阳性。此外，有21名儿童在孤儿院接受了3个月前的HHV-6抗体测试。这些儿童中HHV-6的年龄特异性血清阳性率与普通儿童人群相似。这些数据表明，母婴的亲密接触并不是建立婴儿HHV-6感染的必要条件。为了获得HHV-6在免疫功能低下状态下的毒力的基本数据，我们评估了HHV-6是否会像其他疱疹病毒一样发生再激活或再感染。在23例ES二次发作患者中。3例患者HHV-6抗体滴度明显升高，5例既往发热患者中2例抗体滴度也明显升高。这些结果提示HHV-6再激活或再感染可能在ES的二次发作中起作用。我们通过问卷调查获得了在九州大学医院接受过培训的57名儿科医生关于其12个月以上儿童ES病史的信息。他们的115个孩子中有70个（61%）患有临床ES。ES在日本的发病率远高于美国（约30%）。少

The clinical findings of 47 patients with exanthema subitum (ES) serologically confirmed human herpesvirus-6 (HHV-6) infection were analyzed. The onset age of ES concentrated between 6 and 9 months old, pepeaked at 6 months old. In our seroepidemiologic study, the maternal antibody to HHV-6 disappeared within the same period. Among the 47 patients. 3 were attacked by ES within 2 months after their birth and all of their mothers mothers were seropositive. These results suggested that the onset age of ES is determined by the disappearance of maternal antibody to HHV-6. No correlation was observed between the onset age and mode of feeding (e.g. breast bottle and mixed).Antibodies to HHV-6 in the infants who have been admitted in the neonatal intensive care unit (NICU) for more than 1 year were tested together with their mothers. All of their mothers were seropositive to HHV-6 and 5 of the 6 infants were seropositive to HHV-6. Furthermore. 21 children who have been admitted in an orphanage … More before 3 month of ages were tested for their antibodies to HHV-6. Age specific seroprevalence of HHV-6 in these children was similar to that of the ordinary child population. These data elucidated that intimate contact of mother and child is not neccesary for the establishment of HHV-6 infection in infants.In order to obtain basic data concerning the virulence of HHV-6 in the immunocompromised state, we evaluated whether or not reactivation or reinfection of HHV-6 occurs as other herpesviruses. Among the 23 patients with second attacks of ES. 3 showed significant rises in the HHV-6 lgG antibody titers and 2 of the 5 patients with previous afebrile attacks also showed rises. These results suggest possible role of HHV-6 reactivation or reinfection in some second attack of ES.We have obtained informations from 57 pediatricians who had been trained at Kyushu University Hospital on the history of ES of their own children older than 12 months of age by a questionnaire. Seventy of 115 their children (61%) have had clinical ES. This attack rate of ES in Japan is much higher than that in U. S. A. (approximately 30%). Less