Shrestha Ananta, Basnet Suresh, Kc Sudhamshu
Department of Hepatology, Alka Hospital, Kathmandu 44600, Nepal.
Department of Pulmonary and Critical Care Medicine, University of Maryland School of Medicine, Baltimore, MD 21201, United States.
World J Hepatol. 2024 Apr 27;16(4):506-510. doi: 10.4254/wjh.v16.i4.506.
Hepatitis E virus (HEV) is hyperendemic in South Asia and Africa accounting for half of total Global HEV burden. There are eight genotypes of HEV. Among them, the four common ones known to infect humans, genotypes 1 and 2 are prevalent in the developing world and genotypes 3 and 4 are causing challenge in the industrialized world. Asymptomatic HEV viremia in the general population, especially among blood donors, has been reported in the literature worldwide. The clinical implications related to this asymptomatic viremia are unclear and need further exploration. Detection of viremia due to HEV genotype 1 infection, apparently among healthy blood donors is also reported without much knowledge about its infection rate. Similarly, while HEV genotype 3 is known to be transmitted blood transfusion in humans and has been subjected to screening in many European nations, instances of transmission have also been documented albeit without significant clinical consequences. Epidemiology of HEV genotype 1 in endemic areas often show waxing and waning pattern. Occasional sporadic occurrence of HEV infection interrupted by outbreaks have been frequently seen. In absence of known animal reservoir, where HEV exists in between outbreak is a mystery that needs further exploration. However, occurrence of asymptomatic HEV viremia due to HEV genotype 1 during epidemiologically quiescent period may explain that this phenomenon may act as a dynamic reservoir. Since HEV genotype 1 infection cannot cause chronicity, subclinical transient infection and transmission of virus might be the reason it sustains in interepidemic period. This might be the similar phenomenon with SARS COVID-19 corona virus infection which is circulating worldwide in distinct phases with peaks and plateaus despite vaccination against it. In view of existing evidence, we propose the concept of "Dynamic Human Reservoir." Quiescent subclinical infection of HEV without any clinical consequences and subsequent transmission may contribute to the existence of the virus in a community. The potential for transmitting HEV infection by asymptomatic HEV infected individuals by fecal shedding of virus has not been reported in literature. This missing link may be a key to Pandora's box in understanding epidemiology of HEV infection in genotype 1 predominant region.
戊型肝炎病毒（HEV）在南亚和非洲高度流行，占全球戊型肝炎病毒总负担的一半。戊型肝炎病毒有八种基因型。其中，已知感染人类的四种常见基因型中，基因型1和2在发展中世界流行，基因型3和4在工业化世界构成挑战。文献中已报道普通人群中存在无症状戊型肝炎病毒血症，尤其是在献血者中。与这种无症状病毒血症相关的临床意义尚不清楚，需要进一步探索。也有报道称，在健康献血者中检测到1型戊型肝炎病毒感染导致的病毒血症，但对其感染率了解不多。同样，虽然已知3型戊型肝炎病毒可通过输血在人类中传播，并且在许多欧洲国家已进行筛查，但也有传播病例的记录，尽管没有明显的临床后果。戊型肝炎病毒基因型1在流行地区的流行病学情况通常呈起伏模式。经常可以看到偶尔散发的戊型肝炎病毒感染被疫情打断。在没有已知动物宿主的情况下，疫情间歇期戊型肝炎病毒的存在是一个需要进一步探索的谜团。然而，在流行病学静止期出现1型戊型肝炎病毒导致的无症状戊型肝炎病毒血症，可能说明这种现象可能充当了一个动态宿主。由于1型戊型肝炎病毒感染不会导致慢性化，亚临床短暂感染和病毒传播可能是其在疫情间期持续存在的原因。这可能与严重急性呼吸综合征冠状病毒2（SARS-CoV-2）感染的情况类似，尽管已接种疫苗，但该病毒仍在全球不同阶段呈高峰和平台期循环传播。鉴于现有证据，我们提出了“动态人类宿主”的概念。戊型肝炎病毒的静止亚临床感染没有任何临床后果，随后的传播可能有助于该病毒在社区中的存在。文献中尚未报道无症状戊型肝炎病毒感染者通过粪便排出病毒传播戊型肝炎病毒感染的可能性。这个缺失的环节可能是理解1型基因型戊型肝炎病毒感染流行病学的潘多拉魔盒的关键。
