1390-65421390-6542S1390-6542201800020011710.29019/enfoqueute.v9n2.195EcuadorEcuadorBrazil0006201800062018921171242015647320022003154157-6420127933594-607199920285-9720023613133183-922011111-9201449207-142005Hach2000200141192005441117-25198550551292-5Instituto Geográfico Militar201720004322257-75Ken-a-vision0200331-30197235-57199719983841/31/341-532012201520115622589-981997421132-62003506-5091-31-3169-7420064566696-703World Health Organization19992009866910-5