Nabwera H M, Logan R P
Division of Gastroenterology, University Hospital Queens Medical Centre, Nottingham, UK.
J Physiol Pharmacol. 1999 Dec;50(5):711-22.
Although H. pylori infection is endemic and despite more than 10 years of research, the mode and route of transmission remain elusive. This may, in part, be due to the inherent problems of detecting H. pylori noninvasively. The prevalence of infection varies between countries and is closely related to Growth Domestic Product. An age-cohort effect and data from longitudinal studies suggest that the incidence of infection is much higher in children than adults. In developing countries the prevalence of infection is often more than 80% in young adults, in contrast to less than 10% for similar age groups in developed countries. The observations of mosaicism (in the VacA gene) and a panmycytic population structure imply exchange of genetic material either in or outside of the host, which is supported by the increasing recognition of polyclonal infection and suggests that secondary infection occurs after primary acquisition. In addition, in children persistent primary infection may sometimes occur only after previous (repeated) exposure and/or transient colonisation of the gastric mucosa. H. pylori and other gastric Helicobacter spp are always noninvasive, but other human nongastric Helicobacter spp have sometimes been isolated from the systemic circulation in immunocompromised patients. For nonhuman hosts, intestinal Helicobacter spp are thought to translocate more frequently from the colon to the liver. Within the human host, the oral cavity is the principal extragastric reservoir, although case reports suggest that H. pylori may sometimes be found beyond the 2nd part of the duodenum. The hypothesis that H. pylori is a zoonosis or transmitted as coccoid forms by a vector (pets, houseflies) is not supported by recent research showing that H. pylori is entirely unable to support an aerobic or anaerobic metabolism and that coccoid forms are non-viable. H. pylori is primarily acquired in infancy, most probably via the oroorogastric route, from other family members or close contacts encountered after weaning or socialisation. Further studies to support or refute this hypothesis are required.
尽管幽门螺杆菌感染呈地方性流行，且历经10多年研究，但传播方式和途径仍不明确。这部分可能归因于非侵入性检测幽门螺杆菌存在的固有问题。感染率在不同国家有所差异，且与国内生产总值密切相关。年龄队列效应以及纵向研究数据表明，儿童感染率远高于成人。在发展中国家，年轻成年人中的感染率通常超过80%，而在发达国家，同年龄组的感染率则低于10%。对（空泡毒素A基因中的）镶嵌现象和全血细胞群体结构的观察表明，宿主内外存在遗传物质交换，这一点得到了对多克隆感染认识的不断增加的支持，并提示继发感染发生在初次感染之后。此外，在儿童中，持续性原发性感染有时可能仅在先前（反复）接触和/或胃黏膜短暂定植之后才会出现。幽门螺杆菌和其他胃内螺杆菌属始终是非侵入性的，但在免疫功能低下的患者中，有时会从其血液循环中分离出其他人体非胃内螺杆菌属。对于非人类宿主，肠道螺杆菌属被认为更频繁地从结肠转移至肝脏。在人类宿主中，口腔是胃外的主要储存部位，不过病例报告显示，幽门螺杆菌有时可能在十二指肠第二部以外被发现。幽门螺杆菌是人畜共患病或通过媒介（宠物、家蝇）以球形体形式传播的假说，未得到近期研究的支持，这些研究表明幽门螺杆菌完全无法支持有氧或无氧代谢，且球形体形式无活性。幽门螺杆菌主要在婴儿期获得，最有可能是通过口口或口胃途径，从断奶或社交后接触的其他家庭成员或密切接触者那里感染。需要进一步开展研究以支持或反驳这一假说。
