Review Transmission pathway of Helicobacter pylori: Does food play a role in rural and urban areas? F.F. Vale a, ⁎, J.M.B. Vítor b a Faculty of Engineering Catholic University of Portugal, Estrada Octávio Pato, 2635-631 Rio de Mouro, Portugal b iMed.UL (MedChem Division), Faculty of Pharmacy, University of Lisbon, Av. das Forças Armadas, 1649-003 Lisboa, Portugal abstract article info Article history: Received 18 October 2009 Received in revised form 13 January 2010 Accepted 14 January 2010 Keywords: Helicobacter pylori Transmission Food Water Vehicle Source Rural and urban areas Helicobacter pylori is a Gram-negative microaerophilic bacterium that has colonized the human gastric mucosa. This infection is very common and affects more than half of the human population. The prevalence is however unbalanced between rural developing areas (more than 80%) and urban developed areas (less than 40%). H. pylori is responsible for several pathologies, such as gastritis, peptic ulcer and gastric cancer but its transmission pathway is still not clear. The risk factors for H. pylori infection include poor social and economic development; poor hygienic practices; absence of hygienic drinking water; and unsanitary prepared food. There is evidence supporting a gastro–oral, oral–oral and faecal–oral transmission, but no predominant mechanism of transmission has been yet identified. Transmission may occur in a vertical mode (e.g. from parents to child) or in a horizontal mode (across individuals or from environmental contamination). In either case, the involvement of water and food cannot be excluded as vehicles or sources of infection. Indirect evidence of presence of H. pylori in water and food, namely the detection of its DNA and survival studies after artificial contamination of food and water has been described. This paper reviews data both favourable and against the role of water and food in the transmission of H. pylori, exploring their role as a potential transmission vehicle for person-to-person and food-chain transmission. The likelihood of the transmission pathway in developing rural and developed urban areas appears to be different. In developed areas, person-to-person transmission within families appears to be dominant, while in the rural developing areas the transmission pathway appears to be more complex. In this later case, the transmission by contaminated food, water, or via intensive contact between infants and non-parental caretakers may have a greater influence than within-family transmission. © 2010 Elsevier B.V. All rights reserved. Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Epidemiology: diseases and prevalence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.2. Risk factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.3. Therapy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.4. Geographic strain distribution and globalization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.5. Infection in rural (developing) and urban (developed) environments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.6. Mixed colonization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.7. Coccoid forms: cell death or VBNC? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.8. Concepts of the microbiology of H. pylori . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Routes of transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.1. Person-to-person transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.1.1. Gastro–oral transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1.2. Oral–oral transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1.3. Faecal–oral transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1.4. A role for water in person-to-person transmission? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1.5. A role for food in person-to-person transmission? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 International Journal of Food Microbiology 138 (2010) 1–12 ⁎ Corresponding author. Present address: Faculty of Engineering. Catholic University of Portugal. Estrada Octávio Pato. 2635-631 Rio de Mouro (Lisboa), Portugal. Tel.: +351214269770; fax: +351214269800. E-mail address: filipavale@fe.ucp.pt (F.F. Vale). 0168-1605/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.ijfoodmicro.2010.01.016 Contents lists available at ScienceDirect International Journal of Food Microbiology journal homepage: www.elsevier.com/locate/ijfoodmicro