WHO Report on Global Surveillance of Epidemic-prone Infectious Diseases - Introduction
The scope of this report
This report concentrates on the surveillance of nine infectious epidemic diseases that are either new or volatile or pose an important public health threat. All have high epidemic potential and most are increasing in incidence. They include:
- Yellow fever
- Meningococcal disease
- Dengue fever and dengue haemorrhagic fever
- African trypanosomiasis
- Leishmaniasis and leishmania/HIV co-infection
These diseases are difficult to track because of their complicated epidemic patterns, their ability to develop new strains, and their tendency to spread quickly to new locations. Most of these diseases have high case fatality rates and severe symptoms increasing the urgency of fast identification of new occurrences to prevent further transmission.
These nine diseases have several different transmission patterns. Yellow fever, plague, dengue/dengue haemorrhagic fever, African trypanosomiasis, and leishmaniasis are all vector-borne diseases transmitted by the bite of infected insects; influenza and meningococcal disease have airborne transmission routes; while cholera is transmitted by contaminated food and water, and HIV is transmitted primarily through sexual contact. HIVand HIV-leishmania co-infection can also be transmitted through contact with infected blood either from blood transfusions, contaminated needles or use of contaminated blood products. Vertical transmission from mother to child occurs in both HIV and African trypanosomiasis.
The remainder of this chapter presents a description of the types of data used in the surveillance of the nine diseases presented. This provides insight into the different types of activities that make up disease surveillance systems, and includes a discussion of the uses and limitations of surveillance data. Next, there are observations about how the modern world is impacting on infectious diseases, using examples from the nine diseases covered in the report. Finally some conclusions are drawn.