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. 2024 Aug 24;23(1):258.
doi: 10.1186/s12936-024-05074-y.

Bayesian spatio-temporal modelling of environmental, climatic, and socio-economic influences on malaria in Central Vietnam

Affiliations

Bayesian spatio-temporal modelling of environmental, climatic, and socio-economic influences on malaria in Central Vietnam

Le Thanh Tam et al. Malar J. .

Abstract

Background: Despite the successful efforts in controlling malaria in Vietnam, the disease remains a significant health concern, particularly in Central Vietnam. This study aimed to assess correlations between environmental, climatic, and socio-economic factors in the district with malaria cases.

Methods: The study was conducted in 15 provinces in Central Vietnam from January 2018 to December 2022. Monthly malaria cases were obtained from the Institute of Malariology, Parasitology, and Entomology Quy Nhon, Vietnam. Environmental, climatic, and socio-economic data were retrieved using a Google Earth Engine script. A multivariable Zero-inflated Poisson regression was undertaken using a Bayesian framework with spatial and spatiotemporal random effects with a conditional autoregressive prior structure. The posterior random effects were estimated using Bayesian Markov Chain Monte Carlo simulation with Gibbs sampling.

Results: There was a total of 5,985 Plasmodium falciparum and 2,623 Plasmodium vivax cases during the study period. Plasmodium falciparum risk increased by five times (95% credible interval [CrI] 4.37, 6.74) for each 1-unit increase of normalized difference vegetation index (NDVI) without lag and by 8% (95% CrI 7%, 9%) for every 1ºC increase in maximum temperature (TMAX) at a 6-month lag. While a decrease in risk of 1% (95% CrI 0%, 1%) for a 1 mm increase in precipitation with a 6-month lag was observed. A 1-unit increase in NDVI at a 1-month lag was associated with a four-fold increase (95% CrI 2.95, 4.90) in risk of P. vivax. In addition, the risk increased by 6% (95% CrI 5%, 7%) and 3% (95% CrI 1%, 5%) for each 1ºC increase in land surface temperature during daytime with a 6-month lag and TMAX at a 4-month lag, respectively. Spatial analysis showed a higher mean malaria risk of both species in the Central Highlands and southeast parts of Central Vietnam and a lower risk in the northern and north-western areas.

Conclusion: Identification of environmental, climatic, and socio-economic risk factors and spatial malaria clusters are crucial for designing adaptive strategies to maximize the impact of limited public health resources toward eliminating malaria in Vietnam.

Keywords: Plasmodium; Bayesian; Malaria; Spatio-temporal; Vector-borne disease; Vietnam.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Fig. 1
Fig. 1
Map of study site with administrative boundaries, neighbouring countries, and altitude
Fig. 2
Fig. 2
Raw standardized morbidity ratios of A Plasmodium falciparum and B Plasmodium vivax, classified by districts in Central Vietnam, 2018–2022
Fig. 3
Fig. 3
Decomposed monthly Plasmodium falciparum incidence in Central Vietnam from 2018 to 2022
Fig. 4
Fig. 4
Decomposed monthly Plasmodium vivax incidence in Central Vietnam from 2018 to 2022
Fig. 5
Fig. 5
Spatial distribution of the posterior means of structured random effects for (A) Plasmodium falciparum and (B) Plasmodium vivax
Fig. 6
Fig. 6
Trend analysis of (A) Plasmodium falciparum and (B) Plasmodium vivax in Central Vietnam, from 2018 to 2022

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