Department of Medicine.
J Infect Dis. 2014 Apr 1;209(7):1016-22. doi: 10.1093/infdis/jit620. Epub 2013 Nov 18.
Noroviruses are the most common cause of gastroenteritis in the United States. An understanding of the infectious dose of these viruses is important for risk assessment studies.
Healthy adults were enrolled in a randomized, double-blind, placebo-controlled evaluation of different dosages of Norwalk virus. Eligible subjects were monitored for clinical gastroenteritis, and infection status was determined. The presence of virus in vomitus was also assessed.
Fifty-seven persons were enrolled; 8 received placebo and an additional 8 persons were considered to be nonsusceptible on the basis of being secretor negative. Twenty-one persons were infected (all blood group O or A), and 67% of those infected developed viral gastroenteritis. The 50% human infectious dose was calculated to be 3.3 reverse transcription polymerase chain reaction units (approximately 1320 genomic equivalents [gEq]) for secretor-positive blood group O or A persons and 7.0 (approximately 2800 gEq) for all secretor-positive persons. The time of illness onset was inversely correlated with inoculum dose. The maximal concentration of virus shedding was higher for persons with gastroenteritis. Norwalk virus was identified in 15 of 27 (56%) vomitus samples at a median concentration of 41 000 gEq/mL.
The 50% human infectious dose measured is higher than previous estimates and similar to that of other RNA viruses. Clinical Trials Registration NCT00138476.
诺如病毒是美国最常见的胃肠道疾病病原体。了解此类病毒的感染剂量对于风险评估研究至关重要。
健康成年人参与了一项随机、双盲、安慰剂对照的诺如病毒不同剂量评估研究。合格的研究对象接受临床胃肠炎监测，并确定其感染状态。同时还评估了呕吐物中病毒的存在情况。
共有 57 人入组；8 人接受安慰剂，另外 8 人因非分泌型而被认为不敏感。21 人感染（均为 O 型或 A 型血），67%的感染者发生病毒性胃肠炎。50%人体感染剂量计算为分泌型 O 型或 A 型血者为 3.3 个逆转录聚合酶链反应单位（约 1320 基因组当量[gEq]），所有分泌型阳性者为 7.0（约 2800 gEq）。发病时间与接种剂量呈负相关。有胃肠道症状者的病毒排出量最高。在 27 份（56%）呕吐物样本中检测到 15 份（56%）诺如病毒，中位数浓度为 41000 gEq/mL。
测量得到的 50%人体感染剂量高于既往估计值，与其他 RNA 病毒相似。
NCT00138476。
