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About the Authors:
Miranda Chan
Affiliation: Department of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, Georgia, United States of America
Michael A. Johansson
* E-mail: [email protected]
Affiliation: Dengue Branch, Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, San Juan, Puerto Rico, United States of America
Introduction
Dengue viruses (DENV) are a major cause of illness, hospitalization, and death throughout the tropical and subtropical regions of the world [1]. Despite the prevalence of DENV and the mosquito vectors, Aedes aegypti and Aedes albopictus, some components of the transmission cycle are not well defined. Here we focus on the extrinsic and intrinsic incubation periods of DENV infections. The extrinsic incubation period (EIP) is the viral incubation period between the time when a mosquito takes a viremic bloodmeal and the time when that mosquito becomes infectious. The intrinsic incubation period (IIP) is the time between a human being infected and the onset of symptoms due to the infection. These periods are important determinants of the temporal dynamics of DENV transmission and are therefore critical for clinical diagnosis, outbreak investigation, implementation of prevention and control programming, and mathematical modeling of DENV transmission.
The EIP begins with a mosquito taking an infectious blood meal from a viremic human host. DENV present in the blood meal then invades the midgut, replicates, and eventually disseminates throughout the mosquito, which becomes infectious once virus reaches the salivary glands, at which point the mosquito is infectious and has thus completed the EIP [2]. Since the early 1900s when the etiology of dengue was being investigated, the EIP has been recognized as an important component of DENV transmission dynamics [3]. Due to its known dependence on temperature [4], [5], the EIP plays an important role in efforts to understand the influence of weather and climate on the spatiotemporal dynamics of DENV transmission and to incorporate those effects into mathematical models of DENV transmission (e.g. [6], [7], [8], [9]).
The EIP is generally referenced as being 8–12 days [10], [11], based on two sets of experimental observations [12], [13]. In these experiments, no blood-fed mosquitoes were infectious until 8 days post exposure, but were infectious by 12 days post exposure. These observations have not however been incorporated into explicit statistical models, which...