Analysis of the natural course of HHV-6 and 7 infections ; to elucidate the remaining problems for the infections.

原发性人类疱疹病毒6型（HHV-6）感染可引起婴幼儿皮疹。虽然这种疾病通常是一种良性发热性疾病，但也会出现严重的表现，特别是在中枢神经系统（CNS）中。我们在日本进行了一项关于ES相关脑炎的全国性调查，以确定该病的发生率和临床特征。在2003年1月至2004年12月期间，我们进行了一项由两部分组成的问卷调查，以确定ES相关脑炎的发生率和临床特征。在向医院发送的3357份问卷中，（70.2%）被退回，2，293例（68.3%）符合分析条件。本文报告86例ES相关脑炎，男45例（52.3%），女41例（47.7%）。86例患者中77例（89.5%）经病毒学检查确诊为HHV-6感染。患者平均年龄为14.0±8.8个月。81例患者中41例（50.6%）无后遗症，38例（46.9%）有神经系统后遗症。此外，报告了2例致死性病例（2.5%）。在皮疹出现之前和之后分别有37例（66.1%）和11例（19.6%）患者出现神经系统症状。1例患者（1.8%）出现皮疹时有神经系统症状。43例患者中仅4例（9.3%）观察到白细胞增多，所有患者的CSF蛋白水平均在正常范围内（23.4±14.6mg/d 1）。HHV-6DNA阳性率为53.8%（21/39）。虽然几个临床因素和神经系统后遗症之间的关联进行了评估，只有异常的CT表现是神经系统后遗症的预测因子（P=0.0097）。作为这项调查的结果，我们估计有61.9年的ES相关脑炎病例。疾病预后出乎意料地差。

Primary human herpesvirus 6 (HHV-6) infection can cause exanthem subitum (ES) in infants and young children. Although the disease is generally a benign febrile illness, severe manifestations, particularly in the central nervous system (CNS), can occur. We performed a nationwide survey in Japan for ES-associated encephalitis to determine the frequency and clinical features of the disease.A two-part questionnaire was administered between January 2003 and December 2004 to determine the frequency and clinical features of ES-associated encephalitis.Of 3, 357 questionnaires sent to hospitals, 2, 357 (70.2%) were returned and 2, 293 (68.3%) were eligible for analysis. Eighty-six cases [45 male (52.3%) and 41 female (47.7%)] of ES-associated encephalitis were reported. Seventy-seven (89.5%) of the 86 patients were diagnosed with HHV-6 infection by virological examination. The mean age of the patients was 14.0±8.8 months. Although 41 (50.6%) of 81 patients had no sequelae, 38 (46.9%) had neurological sequelae. Additionally, two fatal cases (2.5%) were reported. Neurological symptoms occurred before and after the appearance of a skin rash in 37 (66.1%) and 11 (19.6%) patients, respectively. One patient (1.8%) had neurological symptoms when the skin rash appeared. Pleocytosis was observed in only four (9.3%) of 43 patients, and CSF protein levels were within a normal range (23.4±14.6mg/d1) in all patients. HHV-6 DNA was detected in 21 (53.8%) of 39 patients. Although an association between several clinical factors and neurological sequelae was evaluated, only abnormal CT findings were a predictor for neurological sequelae (P=0.0097).As a consequence of this survey, we estimate that there are 61.9 annual cases of ES-associated encephalitis. The disease prognosis was unexpectedly poor.