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. 2022 Dec;67(4):1500-1513.
doi: 10.1007/s11686-022-00598-2. Epub 2022 Aug 11.

Spatio-temporal Prediction of the Malaria Transmission Risk in Minab District (Hormozgan Province, Southern Iran)

Abdolreza Salahi-Moghaddam  1 , Habibollah Turki  1 , Masoud Yeryan  2 , Màrius V Fuentes  3
Affiliations

Spatio-temporal Prediction of the Malaria Transmission Risk in Minab District (Hormozgan Province, Southern Iran)

Abdolreza Salahi-Moghaddam et al. Acta Parasitol. 2022 Dec.

Abstract

Introduction: Malaria is the most important parasitic disease in tropical and subtropical regions, with more than 240 million cases reported annually. In Iran, indigenous cases occur in its south-eastern region. The aim of this study is to assess the environmental risk of malaria transmission in an endemic area of southern Iran.

Methods: The study was carried out in Minab district (Hormozgan province, southern Iran), with the aim to assess the environmental risk of malaria, based on a spatio-temporal study, using Growing Degree Days (GDD)-based predictions, larval habitat ecology, MaxEnt spatial predictions and malaria transmission data.

Results: The Gradient Model Risk index showed the highest malaria transmission risk period to be during January-April and October-December. The ecological conditions of water bodies of larval habitats of the four vector species (Anopheles culicifacies, A. dthali, A. fluviatilis and A. stephensi) were assessed, with A. stephensi being the most prevalent and the most widely distributed species.

Conclusion: These findings, together with the MaxEnt Anopheles predictive distribution models, allowed identifying villages in danger of malaria transmission in Minab district. This spatio-temporal prediction of malaria transmission risk should be incorporated in the design of malaria control initiatives towards a local malaria early warning system. Moreover, the proposed transmission risk model can be extrapolated, at local scale, to other malaria endemic areas of tropical and subtropical regions.

Keywords: Anopheline larvae; Environmental risk; GIS; Hormozgan province; Iran; Malaria.

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Conflict of interest statement

On behalf of all authors, the corresponding author states that there is no conflict of interest.

Figures

Fig. 1
Fig. 1
Minab and Sirik districts in the Hormozgan province of Iran
Fig. 2
Fig. 2
Climadiagram of Minab district showing: minimum, maximum and mean temperatures; rainfall; optimum temperatures required for the sporogony cycle of Plasmodium falciparum (30 ºC) and P. vivax (25 ºC); and the minimum and maximum temperatures for the optimum development of Anopheles mosquitoes (20 ºC–30 ºC)
Fig. 3
Fig. 3
Accumulated monthly malaria cases from 2001 to 2012 and Gradient Model Risk (GMR) in Minab district, with the interpolation of the minimal GMR required for Plasmodium falciparum and P. vivax transmission (116)
Fig. 4
Fig. 4
Map of Minab district representing the distribution of malaria cases between 2001 and 2012 reported by health centres. Scale bar = 25 km
Fig. 5
Fig. 5
Altitudinal map (by Digital Elevation Model) and streams map of Minab district representing the distribution of larval habitats and collected larvae. Scale bar = 25 km
Fig. 6
Fig. 6
Annual mean temperature and streams map of Minab district representing the distribution of larval habitats and collected larvae. Scale bar = 25 km
Fig. 7
Fig. 7
Distribution of Anopheles larval habitats and collected larvae in Minab district: a A. culicifacies; b A. dthali; c A. fluviatilis; d A. stephensi. Scale bar = 25 km
Fig. 8
Fig. 8
Jackknife test of variable importance contribution to the MaxEnt model to determine Anopheles larval habitats in Minab district: a A. culicifacies; b A. dthali; c A. fluviatilis; d A. stephensi
Fig. 9
Fig. 9
MaxEnt model predictive map of Anopheles larval habitats overlapped with the distribution of known Anopheles larval habitats and collected larvae in Minab district: a A. culicifacies; b A. dthali; c A. fluviatilis; d A. stephensi. Scale bar = 25 km
Fig. 10
Fig. 10
Endangered villages for malaria transmission in Minab district with permanent and seasonal streams in the background. Scale bar = 25 km
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