Laboratory for Zoonoses and Environmental Microbiology, Centre for Infectious Disease Control Netherlands, National Institute for Public Health and the Environment, PO Box 1, 3720 BA, Bilthoven, The Netherlands.
Risk Anal. 2011 Jun;31(6):940-50. doi: 10.1111/j.1539-6924.2010.01546.x. Epub 2010 Dec 22.
Sources for human hepatitis E virus (HEV) infections of genotype 3 are largely unknown. Pigs are potential animal reservoirs for HEV. Intervention at pig farms may be desired when pigs are confirmed as a source for human infections, requiring knowledge about transmission routes. These routes are currently understudied. The current study aims to quantify the likelihood of pig feces in causing new HEV infections in pigs due to oral ingestion. We estimated the daily infection risk for pigs by modeling the fate of HEV in the fecal-oral (F-O) pathway. Using parameter values deemed most plausible by the authors based on current knowledge the daily risk of infection was 0.85 (95% interval: 0.03-1). The associated expected number of new infections per day was ∼4 (2.5% limit 0.1, the 97% limit tending to infinity) compared to 0.7 observed in a transmission experiment with pigs, and the likelihood of feces causing the transmission approached 1. In alternative scenarios, F-O transmission of HEV was also very likely to cause new infections. By reducing the total value of all explanatory variables by 2 orders of magnitude, the expected numbers of newly infected pigs approached the observed number. The likelihood of F-O transmission decreased by decreasing parameter values, allowing for at most 94% of infections being caused by additional transmission routes. Nevertheless, in all scenarios F-O transmission was estimated to contribute to HEV transmission. Thus, despite the difficulty in infecting pigs with HEV via oral inoculation, the F-O route is likely to cause HEV transmission among pigs.
人类戊型肝炎病毒（HEV）感染 3 型的来源在很大程度上是未知的。猪是 HEV 的潜在动物宿主。当猪被确认为人类感染的来源时，可能需要在养猪场进行干预，这就需要了解传播途径。这些途径目前研究不足。本研究旨在定量评估猪粪便经口摄入导致猪新发 HEV 感染的可能性。我们通过模拟粪便-口腔（F-O）途径中 HEV 的命运来估计猪的日感染风险。使用作者根据现有知识认为最合理的参数值，感染风险为 0.85（95%置信区间：0.03-1）。每天新感染的预期数量约为 4 个（2.5%的下限为 0.1，97%的上限趋于无穷大），而在一项针对猪的传播实验中观察到的感染风险为 0.7，粪便导致传播的可能性接近 1。在替代情景中，F-O 传播也极有可能导致新的感染。通过将所有解释变量的值降低 2 个数量级，新感染猪的预期数量接近观察到的数量。随着参数值的降低，F-O 传播的可能性降低，允许最多 94%的感染由其他传播途径引起。然而，在所有情况下，F-O 传播都被估计会导致 HEV 传播。因此，尽管通过口服接种感染猪感染 HEV 具有一定难度，但 F-O 途径仍可能导致猪群中的 HEV 传播。
