Reporting of selected communicable diseases is required within countries, and in some instances reporting is also required internationally to WHO. Reporting usually takes the form of either a case report or infection reports (some countries only require aggregate reporting), or an outbreak or event report.

1. Case reports: Case reporting provides diagnosis, age, sex and date of onset for each person with the disease. Sometimes it includes identifying information, such as the name and address of the person with the disease. Additional information, such as treatment provided and its duration, are required for certain case reports.
   
   

National legislation or guidelines often indicate which diseases must be reported, who is responsible for reporting, the format for reporting, and how case reports are to be entered into and forwarded within the national system. If there is a requirement for international case reporting (see below), national governments report to WHO.

1. Outbreak or event reports: Outbreak reporting provides information about an increase in the number of cases above the expected of persons with a communicable disease that may be of public concern. The specific disease causing the outbreak may not be included in the list of diseases officially reportable, or it may be of unknown etiology if it is newly recognized or emerging.
   
   

National legislation or guidelines may indicate which types of outbreak must be reported, who is responsible for reporting, the format for reporting, and how case reports are to be entered into and forwarded within the national system. In general, outbreak reporting is required by the most rapid means of communication available. When there is a requirement for outbreak reporting internationally (see below), national governments report to WHO. The diseases listed in CCDM19 are distributed among 5 classes of reporting, referred to by class number throughout the text under section 9B1 of each disease.