WHO Report on Global Surveillance of Epidemic-prone Infectious Diseases - Introduction
- WHO has long-term data on many epidemic infectious diseases. WHO also has the mandate to lead and coordinate the international effort in global surveillance and response.
- The data collected serve many purposes. First, the data are used to alert health officials when there is an epidemic of infectious disease. For diseases that spread rapidly, and that have high case fatality rates if left untreated, timeliness is of utmost important. Since the data are collected over a long period of time, they can also be used to provide a general picture of long-term trends in incidence and case fatality rates.
- The data have many weaknesses. Countries are hesitant to report diseases covered by the International Health Regulations, in part for fear of economic consequences, and its effects on tourism and trade. In addition, for many diseases there is gross underreporting, under diagnosis, and delayed reporting. The quality of reporting varies considerably from country to country. Finally, international data are not completely comparable as reporting systems, case definitions, and the quality and availability of laboratory facilities vary from country to country.
- Despite these caveats, WHO data can provide a global picture of trends in epidemic infectious disease and case fatality rates over a relatively long period of time.