The extent to which micro-scale processes can explain macro-scale observations is a fundamental ecological question that may be crucial to understanding the persistence and re-emergence of vector borne diseases. We investigate the population dynamics of dengue in the metropolis of Rio de Janeiro, Brazil, which experienced sequential serotype invasions and re-emergence over the past three decades. Our previous work extended an analytical approach to determine the number of ‘skip’ years preceding re-emergence for diseases with population growth and under-reporting, and demonstrated that susceptible depletion and replenishment substantially over-estimate the time to re-emergence under ‘well-mixed’ conditions at a city-wide scale for the first dengue invasion (DENV1). We build on those findings to address the effect of localized susceptible depletion on re-emergence time. Using micro-scale case data from the invasion of serotype DENV4 in 2012 in Rio, we estimate the expected DENV4 re-emergence time per neighborhood, assuming that they all share the same underlying transmission rate and reporting rate but differ in the number of susceptible individuals remaining post-invasion. We then fit a stochastic transmission model to smaller-scale case data to estimate transmission parameters for specific regions of the city.
Results/Conclusions
The expected time to re-emergence (number of ‘skip’ years) varies substantially between neighborhoods. Preliminary results suggest that for the typically low reproductive number of the disease, a large spread in re-emergence times may be expected across neighborhoods depending on the reporting rate used. This spread includes considerably faster re-emergence than that obtained earlier for DENV1 when considering the whole city as a large well-mixed population. Our work underscores the importance of incorporating small scale heterogeneity in population density into city-wide models of transmission.