Explicit characterization of human population connectivity reveals long run persistence of interregional dengue shocks

Abstract

Dengue is hyper-endemic in Singapore and Malaysia, and daily movement rates between the two countries are consistently high, allowing inference on the role of local transmission and imported dengue cases. This paper describes a custom built sparse space–time autoregressive (SSTAR) model to infer and forecast contemporaneous and future dengue transmission patterns in Singapore and 16 administrative regions within Malaysia, taking into account connectivity and geographical adjacency between regions as well as climatic factors. A modification to forecast impulse responses is developed for the case of the SSTAR and is used to simulate changes in dengue transmission in neighbouring regions following a disturbance. The results indicate that there are long-term responses of the neighbouring regions to shocks in a region. By computation of variable inclusion probabilities, we found that each region’s own past counts were important to describe contemporaneous case counts. In 15 out of 16 regions, other regions case counts were important to describe contemporaneous case counts even after controlling for past local dengue transmissions and exogenous factors. Leave-one-region-out analysis using SSTAR showed that dengue transmission counts could be reconstructed for 13 of 16 regions' counts using external dengue transmissions compared to a climate only approach. Lastly, one to four week ahead forecasts from the SSTAR were more accurate than baseline univariate autoregressions.

Impact of sars-cov-2 interventions on dengue transmission

“…Four serotypes of the dengue virus exist and predominate in different localities [13]. The active circulation of all four serotypes in Southeast Asia, where dengue is hyper-endemic, leads to complex cross-immunity dynamics at the population level, causing multi-annual cycles of outbreaks [9] which may be highly persistent [14,15]. In Malaysia, Singapore and Thailand, all four serotypes are in active circulation, with switches in the predominantly reported serotypes over time observed in tandem with a dramatic rise in reported case counts [16][17][18].…”

The epidemiologic and economic burden of dengue in Singapore: A systematic review

“…Notwithstanding vector control, persistent transmission of all dengue serotypes occurs in Singapore, whereas across-type interactions contribute to the emergence of outbreaks [ 68 ]. Coupled with climate change, increased travel to and from Singapore, as measured through air passenger flow, can lead to DENV lineage movement, long-run local transmission, and seeding of outbreaks [ 9 , 69 , 70 ].…”

Hyperendemicity associated with increased dengue burden

“…A large body of work has been published on the potential causes for persistent dengue transmission. Some of these include population renewal [ 22 ] and spatio-temporal heterogeneity which may lead to source–sink dynamics on the national [ 23 ] and regional scale [ 15 ]. Vector dynamics and immunological interactions [ 4 , 24 ] are also posited as drivers of multi-annual cycles of outbreaks.…”

“…It requires less explicit assumptions of the underlying disease process and is computationally straightforward to estimate the underlying parameters of interest. Past work has employed this technique to infer underlying ecological processes [ 14 ] as well as the spatio-temporal spread of diseases [ 15 ], but no work has attempted to employ this class of models for inferring hyperendemic disease dynamics on the population level.…”