Impact of Climate Variability and Abundance of Mosquitoes on Dengue Transmission in Central Vietnam

Abstract

Dengue fever is an important arboviral disease in many countries. Its incidence has increased during the last decade in central Vietnam. Most dengue studies in Vietnam focused on the northern area (Hanoi) and southern regions but not on central Vietnam. Dengue transmission dynamics and relevant environmental risk factors in central Vietnam are not understood. This study aimed to evaluate spatiotemporal patterns of dengue fever in central Vietnam and effects of climatic factors and abundance of mosquitoes on its transmission. Dengue and mosquito surveillance data were obtained from the Department of Vector Control and Border Quarantine at Nha Trang Pasteur Institute. Geographic Information System and satellite remote sensing techniques were used to perform spatiotemporal analyses and to develop climate models using generalized additive models. During 2005–2018, 230,458 dengue cases were reported in central Vietnam. Da Nang and Khanh Hoa were two major hotspots in the study area. The final models indicated the important role of Indian Ocean Dipole, multivariate El Niño-Southern Oscillation index, and vector index in dengue transmission in both regions. Regional climatic variables and mosquito population may drive dengue transmission in central Vietnam. These findings provide important information for developing an early dengue warning system in central Vietnam.

Modeling the association between Aedes aegypti ovitrap egg counts, multi-scale remotely sensed environmental data and arboviral cases at Puntarenas, Costa Rica (2017–2018)

“…This result is in accordance with global observations for dengue, chikungunya and Zika ( Wallace et al., 2018 ) where temperature has been shown as an important factor to explain time series of dengue cases across the globe ( Stoddard et al., 2014 ; Chuang et al., 2017 ; Siraj et al., 2017 ; Oidtman et al., 2019 ). However, at the reduced spatial scale of this study we also found an impact for NDVI, a factor that has been reported as significant for dengue transmission dynamics at a country-wide scale in Costa Rica ( Fuller et al., 2009 ) and Vietnam ( Nguyen et al., 2020 ). This result might be related to the fact that vegetation growth is associated with several weather variables, like rainfall and temperature ( Pettorelli et al., 2005 ).…”

“…Overall, our results also highlight the value of environmental information derived from satellite images for the surveillance of Ae. aegypti and the arboviruses it transmits, as documented in Southeast Asia ( Nguyen et al., 2020 ). This pattern has also been observed for Culex pipiens L. and West Nile virus transmission in the USA ( Chuang et al., 2012 ; Chuang & Wimberly, 2012 ; Poh et al., 2019 ); and Anopheles albimanus (Wiedemann) abundance and malaria infection in Mesoamerica ( Hurtado et al., 2018a , b ; Rejmankova et al., 1993 ; Rigg et al., 2019 ).…”

“…We also downloaded images for the Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI), both of which are considered proxies for vegetation growth ( Pettorelli et al., 2005 ) and have been extensively used to study the ecology of mosquitoes ( Hurtado et al., 2018b ; Chaves et al., 2019 ; Poh et al., 2019 ; Rigg et al., 2019 ; Nguyen et al., 2020 ; Chaves & Friberg, 2021 ) and other insect vectors ( Kitron et al., 1996 ). The images for vegetation indices were downloaded for the multiple spatial scales encompassed by MODIS, Landsat 8 and Sentinel 2.…”

Simple clinical and laboratory predictors to improve empirical treatment strategies in areas of high scrub typhus and dengue endemicity, central Vietnam

“…Khanh Hoa is hyper endemic for dengue fever, and was a major hotspot among the 11 provinces in the central Vietnam with an average of 39,876 cases/100,000 population/year during 2011–2018 [ 21 , 44 ]. Dengue incidence peaked at 40,204 cases /100,000 in 2016, and decreased to 920/100,000 in 2019.…”

Impact of Climate Variability and Incidence on Dengue Hemorrhagic Fever in Palembang City, South Sumatra, Indonesia

“…Climatic factors such as temperature, humidity, and rainfall [43], [44], [45] [46] can prolong the transmission period of DHF [47]. Temperatures of 24-39°C play a significant role in mosquitoes' development, survival, and feeding behavior to promote viral replication in vectors [48]; thus, DHF will increase by 35% per 1°C [49].…”