Mathematical and statistical analyses of the spread of dengue

Abstract

This paper is aimed at clarifying the contributions of mathematical and statistical approaches to dengue epidemiology without delving into mathematical details and sharing the basic theory and its applications regardless of the reader's mathematical background. The practical importance of the basic reproduction number, R0, for dengue is highlighted in relation to the critical proportion of vaccination required to eradicate the disease in the future, and three different methods to estimate R0, (i) final size equation; (ii) intrinsic growth rate; and (iii) age distribution, are concisely explained with published estimates and examples. Although the estimates of R0 most likely depend on the ecological characteristics of the vector population, it would be appropriate to assume that serotype-nonspecific R0 for dengue is approximately 10, at least in planning vaccination strategies in endemic areas. Statistical approaches to determining the periodicity of epidemics, cocirculation of different serotypes (relevant to pathogenesis of dengue haemorrhagic fever), and the significance of spatial heterogeneity are subsequently discussed. Whereas the dengue epidemic is partly characterized by a super-annual cycle with 3-4-year intervals, it is known only that this pattern is determined by the intrinsic dynamics of dengue and not by environmental factors. Although antibody-dependent enhancement was determined as a factor permitting the coexistence of the four serotypes of dengue, a more detailed understanding requires further data. To base the transmission dynamics of dengue on firm evidence and apply the results to dengue control, it is essential that field and laboratory professionals and theoretical specialists interact more.