Asymptomatic transmission shifts epidemic dynamics

• Published in: Mathematical biosciences and engineering : MBE Vol. 18; no. 1; pp. 92 - 111
• Main Authors: Lv, Jinlong, Guo, Songbai, Cui, Jing-An, Tian, Jianjun Paul
• Format: Journal Article
• Language: English
• Published: United States AIMS Press 01.01.2021
• Subjects: asymptomatic transmission; basic reproduction number; final size; asymptomatic transmission; final size; basic reproduction number
• ISSN: 1551-0018; 1551-0018
• DOI: 10.3934/mbe.2021005

Asymptomatic transmission of infectious diseases has been recognized recently in several epidemics or pandemics. There is a great need to incorporate asymptomatic transmissions into traditional modeling of infectious diseases and to study how asymptomatic transmissions shift epidemic dynamics. In this work, we propose a compartmental model with asymptomatic transmissions for waterborne infectious diseases. We conduct a detailed analysis and numerical study with shigellosis data. Two parameters, the proportion $p$ of asymptomatic infected individuals and the proportion $k$ of asymptomatic infectious individuals who can asymptomatically transmit diseases, play major rules in the epidemic dynamics. The basic reproduction number $\mathscr{R}_{0}$ is a decreasing function of parameter $p$ when parameter $k$ is smaller than a critical value while $\mathscr{R}_{0}$ is an increasing function of $p$ when $k$ is greater than the critical value. $\mathscr{R}_{0}$ is an increasing function of $k$ for any value of $p$. When $\mathscr{R}_{0}$ passes through 1 as $p$ or $k$ varies, the dynamics of epidemics is shifted. If asymptomatic transmissions are not counted, $\mathscr{R}_{0}$ will be underestimated while the final size may be overestimated or underestimated. Our study provides a theoretical example for investigating other asymptomatic transmissions and useful information for public health measurements in waterborne infectious diseases.