We searched for peer-reviewed papers recorded in PubMed between January 1990 and May 2016. A full set of search terms is available in Table S1. Two expert reviewers at the National Food Agency (NFA) independently assessed each study according to a list of pre-determined criteria (Table 1). Articles were initially screened according to title and abstract. Articles that were deemed eligible by either one or both reviewers during screening of abstracts were then reviewed in full text by both reviewers and were subsequently included only if both reviewers were in agreement. If consensus could not be reached by discussion, a third reviewer at the NFA assessed the article in full text. Additional papers that were identified in the reference list of the included articles were also included in the review, if they fulfilled our selection criteria.
Inclusion and exclusion criteria for reviewed articles
| . | Inclusion . | Exclusion . |
|---|---|---|
| Population | Resident population | Animals |
| Travellers | ||
| Underlying chronic disease | ||
| Exposure | Municipal drinking water systems | Private drinking water systems |
| Ground water | Recreational water | |
| Surface water | Rain water | |
| Changes in water quality | Sea water | |
| Weather | ||
| Changes/disturbances in water production | ||
| Changes/disturbances in water distribution | ||
| Outcome | Gastroenteritis | Outbreaks only |
| Non-gastrointestinal diseases | ||
| Diseases from a non-infectious source | ||
| Geographic area | North America | Asia |
| Europe | Africa | |
| South America | ||
| Australasia | ||
| Language | English | All other languages |
| Swedish | ||
| Danish | ||
| Norwegian | ||
| French | ||
| Study type | Peer-reviewed articles | Reviews |
| Risk assessments | ||
| Grey literaturea | ||
| Other literature | ||
| Publication period | January 1990–May 2016 | Pre- 1990 |
| . | Inclusion . | Exclusion . |
|---|---|---|
| Population | Resident population | Animals |
| Travellers | ||
| Underlying chronic disease | ||
| Exposure | Municipal drinking water systems | Private drinking water systems |
| Ground water | Recreational water | |
| Surface water | Rain water | |
| Changes in water quality | Sea water | |
| Weather | ||
| Changes/disturbances in water production | ||
| Changes/disturbances in water distribution | ||
| Outcome | Gastroenteritis | Outbreaks only |
| Non-gastrointestinal diseases | ||
| Diseases from a non-infectious source | ||
| Geographic area | North America | Asia |
| Europe | Africa | |
| South America | ||
| Australasia | ||
| Language | English | All other languages |
| Swedish | ||
| Danish | ||
| Norwegian | ||
| French | ||
| Study type | Peer-reviewed articles | Reviews |
| Risk assessments | ||
| Grey literaturea | ||
| Other literature | ||
| Publication period | January 1990–May 2016 | Pre- 1990 |
aGrey literature is that which is produced on all levels of government, academics, business and industry in print and electronic formats, but which is not controlled by commercial publishers, i.e., where publishing is not the primary activity of the producing body (Schöpfel 2010).