Estimation of reproduction number of dengue transmission in a partially susceptible population

Dengue fever has been prevalent for decades in human population and consequently, the human population is partially susceptible to the disease since partial immunity has been gained for those who recovered from dengue infection. We shall obtain an estimation formula for the reproduction number of dengue transmission when the human population is not completely susceptible. This is achieved by taking the number of infected cases periodically notified by surveillance organizations as the solution of a mathematical model for dengue transmission. As an application, the estimation formula is used to estimate the reproduction number of dengue transmission in Singapore in the years 2013 and 2014.