Prevalence rates are derived from Health Ministry reports and individual publications from peer-review journals.  When available, linked references appear for the latter. 

Incidence rates are either derived directly from Health Ministry reports and publications or calculated as cases per 100,000 against an automatically-updated mid-year-population table in our database. 

Cases from outbreaks are included in the total number of cases per year for that country. The accuracy and methods used in individual outbreaks will vary by source, and cannot be used to calculate total cases per year (unless so stated by the source itself).