Influenza Statistics and the Evolution of the International Classification of Diseases

The International Classification of Diseases (ICD) is a classification system whose origins can be traced to the mid-nineteenth century. The ICD was initially developed as a tool for the collection of statistical data on mortality, and subsequently on morbidity. Over time, the scope of its application has broadened to encompass other functions, including the collection of epidemiological information. In the present era, the surveillance of infectious diseases, and thus also of influenza, is based precisely on epidemic intelligence. However, the management of this disease has consistently exhibited distinctive characteristics, primarily due to the rapid spread of the pathogen, its mild effects and widespread underreporting, caused by different medical practices following diagnosis. This article will examine how the maintenance of the anatomical principle in the classification of influenza was in line with the needs of disease surveillance, and suggests an in-depth study of the reciprocal influences between it and the ICD in their evolution during the first three decades of the WHO.