© World Health Organization (WHO). Source of data: Swiss Tropical and Public Health Institute. The designations employed and the presentation of the material in this publication do not imply the expression of any opinion whatsoever on the part of the World Health Organization concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. Dotted and dashed lines on maps represent approximate borderlines for which there may not yet be full agreement. The borders of the map provided reflect the current political and geographic status as of the date of publication (2019).