Table 2.

Selection criteria for systematic literature review.

Inclusion criteria
(i) Publications listed from January 1, 1990 to December 31, 2013
(ii) Studies in English language
(iii) Research conducted in human subjects
(iv) Studies listed in PubMed database or Embase database or WHO website or PAHO website
(v) Study designs: case-control, cohort, randomized control trials
(vi) At least one water related exposure variable that could be categorized either as improved or unimproved drinking water source [4]
(vii) Water is consumed by drinking
Exclusion criteria
(i) Descriptive cross sectional studies that did not present odds ratio, case reports and case series
(ii) Studies that did not present water related risk-factors
(iii) Studies conducted in typhoid non-endemic area are excluded in the estimation of pooled odds ratio