Abstract
The mosquito-borne viruses dengue (DENV), Zika (ZIKV), and chikungunya (CHIKV), now co-endemic in the Americas, pose growing threats to health worldwide. However, it remains unclear whether there exist interactions between these viruses that could shape their epidemiology. This study advances knowledge by assessing the transmission dynamics of co-circulating DENV, ZIKV, and CHIKV in the city of Fortaleza, Brazil. Spatiotemporal transmission dynamics of DENV, ZIKV, and CHIKV were analyzed using georeferenced data on over 210,000 reported cases from 2011 to 2017 in Fortaleza, Brazil. Local spatial clustering tests and space-time scan statistics were used to compare transmission dynamics across all years. The transmission of co-circulating viruses in 2016 and 2017 was evaluated at fine spatial and temporal scales using a measure of spatiotemporal dependence, the τ-statistic. Results revealed differences in the diffusion of CHIKV compared to previous DENV epidemics and spatially distinct transmission of DENV/ZIKV and CHIKV during the period of their co-circulation. Significant spatial clustering of viruses of the same type was observed within 14-day time intervals at distances of up to 6.8 km (p<0.05). These results suggest that arbovirus risk is not uniformly distributed within cities during co-circulation. Findings may guide outbreak preparedness and response efforts by highlighting the clustered nature of transmission of co-circulating arboviruses at the neighborhood level. The potential for competitive interactions between the arboviruses should be further investigated.
Highlights
Mosquito-borne viruses pose a mounting challenge in the context of climate change, rapid urbanization, and inadequate access to infrastructure [1,2]
Most of the global population is at risk of infection with dengue, Zika, and chikungunya viruses, all transmitted by the Aedes mosquitoes
Our findings suggest that co-circulation may alter the transmission dynamics of these mosquito-borne viruses
Summary
Mosquito-borne viruses pose a mounting challenge in the context of climate change, rapid urbanization, and inadequate access to infrastructure [1,2]. Dengue (DENV), Zika (ZIKV), and chikungunya (CHIKV) viruses, all transmitted by the Aedes mosquitoes, are endemic to much of the Americas [1]. Four billion people worldwide are estimated to be at risk of a DENV infection, and the share at risk of ZIKV and CHIKV is expected to rise [1,3]. In their acute phases, these infections share similar clinical presentations of fever, rash, and joint pain. More severe complications include dengue hemorrhagic fever, congenital Zika syndrome (CZS), and post-chikungunya chronic inflammatory joint disease [1]. Improving the preparedness and response to arbovirus outbreaks, as well as treatment management efforts, requires a better understanding of transmission dynamics in the context of co-circulation, including how these viruses interact and spread [6,7]
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