Predicting the environmental suitability for Anopheles stephensi under the current conditions in Ghana.

Vector-borne diseases emergence, particularly malaria, present a significant public health challenge worldwide. Anophelines are predominant malaria vectors, with varied distribution, and influenced by environment and climate. This study, in Ghana, modelled environmental suitability for Anopheles stephensi, a potential vector that may threaten advances in malaria and vector control. Understanding this vector's distribution and dynamics ensures effective malaria and vector control programmes implementation. We explored the MaxEnt ecological modelling method to forecast An. stephensi's potential hotspots and niches. We analysed environmental and climatic variables to predict spatial distribution and ecological niches of An. stephensi with a spatial resolution of approximately 5 km2. Analysing geospatial and species occurrence data, we identified optimal environmental conditions and important factors for its presence. The model's most important variables guided hotspot prediction across several ecological zones aside from urban and peri-urban regions. Considering the vector's complex bionomics, these areas provide varying and adaptable conditions for the vector to colonise and establish. This is shown by the AUC = 0.943 prediction accuracy of the model, which is considered excellent. Based on our predictions, this vector species would thrive in the Greater Accra, Ashanti Central, Upper East, Northern, and North East regions. Forecasting its environmental suitability by ecological niche modelling supports proactive surveillance and focused malaria management strategies. Public health officials can act to reduce the risk of malaria transmission by identifying areas where mosquitoes may breed, which will ultimately improve health outcomes and disease control.

Mapping current and future risk of scorpion sting from a species with low medical concern, Mesobuthus phillipsii (Scorpiones: Buthidae) in Iran.

Scorpion stings are one of the most important health challenges and high priority research topic in public health. In this study, we aimed to model habitat suitability of the Mesobuthus phillipsii (Pocock 1889), a species with low medical concern, under current and future climatic conditions in Iran. We also identified vulnerable populations to scorpion stings in the country. Scorpion sting risk modeling was done using an ensemble approach by considering two species distribution modeling methods: MaxEnt and Random Forest methods. Distribution modeling was performed using the sdm R package. The results showed that due to climate change in 2070, the high-risk areas will increase from 20,839 to 79,212 km2. Habitats with a moderate risk of scorpion stings will also increase from 139,347 to 222,833 km2. Consequently, the number of villages in high-risk areas of scorpion stings will increase from 2,870 to 7,017, while this number will increase from 12,759 to 20,104 in the case of medium-risk villages. The results of this study can be used for scorpion stings management in Iran. This study can be used as an example for similar studies on scorpions with high medical emergency.

Development of a degree-day model to predict the growth of Anopheles stephensi (Diptera: Culicidae): implication for vector control management.

Anopheles stephensi is an efficient vector of malaria parasites in Iran. Despite its importance in malaria transmission, there is a scarcity of accurate predictive models of its rates of development at different temperatures. A laboratory colony of An. stephensi, collected from Bandar Abbas County, southern Iran, was established, and all its developmental stages were maintained in temperature-controlled incubators so that the water temperature set at 5, 8, 10, 12.5, 14, 28, 38, 39.5, 42, and 45(±0.2) °C for different treatments until subsequent adult emergence. The Lower and Upper Developmental Temperatures (LDT and UDT) and the growth degree-day (GDD) were calculated for each development stage. A 12-mo population dynamics survey of the larvae and adults of An. stephensi was performed in 3 malaria-endemic villages (Geno, Hormoodar, and Sarkhoon) of Bandar Abbas County, and the obtained data were matched with the constructed GDD model. Based on the field meteorological and dynamics data, the model was verified in the field and used to determine the appropriate date to start spraying. The LDT was determined to be 8.19, 9.74, 8.42, 5.6, 13.57, and 10.03 °C for egg hatching, first, second, and third ecdysis, pupation, and eclosion events, respectively. The UDT was 38 °C for all developmental stages. The thermal requirement for the development of all immature stages of An stephensi was determined to be 187.7 (±56.3) GDD above the LDT. Therefore, the appropriate date to start residual spraying is when the region's GDD reaches 187.7 (±56.3). Given the climatic conditions in Bandar Abbas County, it is expected that the first activity peak of adult An. stephensi would be in March. Field observations showed that An. stephensi activity starts in February and peaks in March. The GDD model can provide a good estimate for peak An. stephensi activity and indicate the optimal deployment time of residual spraying operations against the multiplication and development of malaria parasites inside the vector.

Modeling the Effect of Climate Change on the Distribution of Main Malaria Vectors in an Endemic Area, Southeastern Iran.

Background: Although malaria is endemic in some areas of southeastern Iran, following the successful national malaria elimination plan (NMEP), the local transmission area has been shrunk. This study was aimed to evaluate the effect of climate change on the distribution of main vectors. Methods: All documents related to research investigations conducted in Kerman Province on malaria vectors published during 2000-2019 were retrieved from scientific databases. Spatial distributions of the main vectors were mapped and modeled using MaxEnt ecological model. The future environmental suitability for main vectors was determined under three climate changes scenarios in the 2030s. Results: Five malaria vectors are present in Kerman Province. The best ecological niches for these vectors are located in the southern regions of the province under the current climatic condition as well as different climate change scenarios in the 2030s. Conclusion: Climate change in 2030 will not have a significant impact on the distribution of malaria vectors in the region. Entomological monitoring is advised to update the spatial database of Anopheles vectors of malaria in this malaria receptive region.

Predicting current and future high-risk areas for vectors and reservoirs of cutaneous leishmaniasis in Iran.

Climate change will affect the distribution of species in the future. To determine the vulnerable areas relating to CL in Iran, we applied two models, MaxEnt and RF, for the projection of the future distribution of the main vectors and reservoirs of CL. The results of the models were compared in terms of performance, species distribution maps, and the gain, loss, and stable areas. The models provided a reasonable estimate of species distribution. The results showed that the Northern and Southern counties of Iran, which currently do not have a high incidence of CL may witness new foci in the future. The Western, and Southwestern regions of the Country, which currently have high habitat suitability for the presence of some vectors and reservoirs, will probably significantly decrease in the future. Furthermore, the most stable areas are for T. indica and M. hurrianae in the future. So that, this species may remain a major reservoir in areas that are present under current conditions. With more local studies in the field of identifying vulnerable areas to CL, it can be suggested that the national CL control guidelines should be revised to include a section as a climate change adaptation plan.

Climate change and its effect on the vulnerability to zoonotic cutaneous leishmaniasis in Iran.

Zoonotic cutaneous leishmaniasis (ZCL) is an important vector-borne disease with an incidence of 15.8 cases per 100,000 people in Iran in 2019. Despite all efforts to control the disease, ZCL has expanded into new areas during the last decades. The aim of this study was to predict the best ecological niches for both vectors and reservoirs of ZCL under climate change scenarios in Iran. Several online scientific databases were searched. In this study, various scientific sources (Google Scholar, PubMed, SID, Ovid Medline, Web of Science, Irandoc, Magiran) were searched. The inclusion criteria for this study included all records with spatial information about vectors and reservoirs of ZCL which were published between 1980 and 2019. The bioclimatic data were downloaded from online databases. MaxEnt model was used to predict the ecological niches for each species under two climate change scenarios in two periods: the 2030s and 2050s. The results obtained from the model were analysed in ArcMap to find the vulnerability of different provinces for the establishment of ZCL foci. The area under the curve (AUC) for all models was >0.8, which suggests the models are able to make an accurate prediction. The distribution of all studied species in different climatic conditions showed changes. The variables affecting each of the studied species are introduced in the article. The predicted maps show that by 2050 there will be more suitable areas for the co-occurrence of vector and reservoir(s) of ZCL in Iran compared to the current climate condition and RCP2.6 scenario. An area in the northwest of Iran is predicted to have suitable environmental conditions for both vectors and reservoirs of ZCL, although the disease has not yet been reported in this area. These areas should be considered for field studies to confirm these results and to prevent the establishment of new ZCL foci in Iran.

Current Situation of Malaria and Resistance of Main Vectors to WHO Recommended Insecticides in an Endemic Area, Southeastern Iran.

Although malaria is endemic in some areas of southeastern Iran, following the successful national malaria elimination plan, the local transmission area has been shrunk. The main cases in Iran are due to Plasmodium vivax followed by P. falciparum. This study was aimed to determine the current situation of malaria in Kerman Province of Iran and evaluate the insecticide resistance of main vectors. The field study was conducted in 2019. Data of new malaria cases were obtained from the health centers for the period of 2009-2018. Susceptibility status of Anopheles stephensi and An. dthali was evaluated against dichlorodiphenyltrichloroethane, Dieldrin, Malathion, Bendiocarb, Deltamethrin, and Temephos at the diagnostic dose. A total of 522 malaria cases were recorded and divided into indigenous (33.14%) and imported (66.86%) categories. The highest incidence of the disease was reported from the southern areas of the province, where all indigenous cases occurred. Adults of An. stephensi were resistant to dichlorodiphenyltrichloroethane while its resistance to be confirmed to dieldrin, bendiocarb and deltamethrin. As An. dthali had less than 98% mortality against bendiocarb, the resistance status should be confirmed with more tests. Our findings showed both species had less than 98% mortality against bendiocarb and deltamethrin insecticides which are used in malaria vector control program in Iran. Due to the susceptibility of these vectors to temephos, larviciding can be advised for vector control in this area.