“…Thirteen studies included travelers recruited at travel clinics when seeking travel advice [7,9e12,14,23,24,28,29,34,40,42] in Europe [7,11,12,14,23,24,28,34,40], Australia [9], US [10], Canada [42] and Asia [29]. Travelers were also recruited through travel agencies (n Z 5) [7,25,29,30,34] in Europe [7,25,34] and Asia [29,30], business corporations in Europe (n Z 2) [13,21], universities (n Z 2) in Australia [19] and the US [27], a commercial airline in the US (n Z 1) [18], a Japanese embassy in Africa (n Z 1) [29], post-Hajj seminars or social gatherings or randomized trials in Australia (n Z 1) [6]; one study was conducted among foreign backpackers recruited in the Khao San Road area, Bangkok, Thailand [26] and another among missionary personnel and their families stationed abroad (n Z 1) [45]. Some studies combined several sources of recruitment [7,29,34].…”