Articles were obtained through an extensive review of published and unpublished material. We did a Medline search of articles on pertussis complications, epidemiology, mortality, prevention, and control and transmission published since 1966. The articles were then searched to limit them to those yielding mortality estimates before obtaining and quality assessing the articles. WHO regional office databases and hand searches of EPI literature and other collections of literature were done without
ReviewHow best to estimate the global burden of pertussis?
Section snippets
Background
The WHO produces the World Health Report to help set national and international priorities in health.1 Such a report creates a challenge with respect to pertussis. In most countries in the world, surveillance systems, even good ones, underestimate the number of pertussis cases and deaths from pertussis.2 Consequently, pertussis is not perceived to be a significant health problem in many countries. Pertussis is one of the diseases for which the WHO and national authorities need good information
Methods
Our starting point for the methods was the approach taken by Galazka3 for previous global estimates. The evidence base for some of the parameters used by Galazka had not been fully described, and we made use of further evidence that has accumulated since Galazka developed his method. For the Global Burden of Disease report, WHO requires numbers of pertussis cases and deaths by age and country. Relevant age groups for pertussis in children were under 1 year, 1–4 years, and 5-14 years. Reliable
Results
In 1999 there were an estimated 48·5 million pertussis cases in the world (table 3). Deaths from pertussis were estimated at 390 000 by the model, reduced to 295 000 after adjustment for the envelope and the cause-of-death analysis described above. Cases in the African Region accounted for 26·3% of the total (in 15·7% of the world's children under 15 years), and in the South East Asian Region for 25·7% of all cases (in 27·6% of the world's children under 15 years). Although the estimated CFR is
Discussion
This simple approach yields estimates that are suitable for setting global and regional vaccination programme priorities. The results do not differ greatly from those obtained by Galazka but the basis for the parameters is more explicit, and we have identified the priorities for improving the evidence base. The approach can be modified in future as more information becomes routinely available.
Comparing case numbers with UK notifications and adjusting for underascertainment, the model still
Search strategy and selection criteria
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