Spatial Analysis of Malaria Cases and Anopheles Species in East Java Region, Indonesia

doi:10.21203/rs.3.rs-4936464/v1

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Research Article

Spatial Analysis of Malaria Cases and Anopheles Species in East Java Region, Indonesia

https://doi.org/10.21203/rs.3.rs-4936464/v1

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Malaria remains a significant public health challenge worldwide, including in Indonesia, especially in East Java. This study aims to analyze the spatial distribution of malaria cases and Anopheles species that act as vectors in the area. Using an observational design with a cross-sectional approach, malaria case data were collected from the Provincial Health Office and public health centers documented in the malaria information system during the period 2021–2023. In addition, Anopheles larvae samples were taken from locations in each region in East Java. The results of the analysis show that the distribution of malaria cases is uneven, with hotspots identified in several coastal areas, mountains and cities, such as Malang, Trenggalek, and Batu. The presence of Anopheles species, especially An. sundaicus and An. maculatus, contributes to malaria transmission, with An. sundaicus more common in coastal areas and An. maculatus in valleys and rice fields. Environmental factors, such as temperature, humidity, and rainfall, as well as socio-economic factors, such as population density, affect the distribution of malaria. This study emphasizes the importance of an ecosystem-based approach in malaria control, as well as the need to improve access to health services and community education. These findings provide important insights for the development of more effective and sustainable health policies in malaria control efforts in East Java.

Malaria

Anopheles

Climate Change

Epidemiology

Malaria remains a significant public health challenge globally, particularly in tropical regions like Southeast Asia. The World Health Organization (WHO) reported in 2021 that there were approximately 241 million malaria cases worldwide, with an estimated 627,000 deaths, predominantly in sub-Saharan Africa but also significantly affecting Southeast Asia (World Health Organization, 2021). In Indonesia, malaria continues to be a pressing issue, especially in regions like East Java, where the ecological conditions favor the proliferation of Anopheles mosquitoes, the primary vectors of the malaria parasite.

East Java is a region characterized by diverse topography, including coastal areas, lowlands, and highlands, each offering unique habitats for different Anopheles species(Arwati et al., 2018)(Elyazar, Hay, et al., 2011) (Susanti et al., 2019). This ecological diversity complicates the control and eradication efforts as different species may exhibit varying behaviors, breeding sites, and susceptibility to control measures. Understanding the spatial distribution and the specific Anopheles species involved in malaria transmission is crucial for developing targeted intervention strategies.

Despite ongoing efforts to combat malaria, the disease persists due to several factors, including environmental changes, vector behavior, and human activities. For instance, deforestation, agricultural practices, and urbanization can alter mosquito habitats, leading to changes in the distribution and abundance of Anopheles species (Leksono, 2017)(Pang et al., 2020). Additionally, resistance to insecticides among mosquito populations poses a significant challenge to vector control programs (Hemingway et al., 2016). Therefore, there is a need for continuous monitoring and analysis of malaria cases and Anopheles species distribution to adapt and optimize control strategies effectively.

Recent advancements in spatial epidemiology and geographic information systems (GIS) have revolutionized the study of infectious diseases, including malaria. Spatial analysis allows researchers to visualize and analyze the distribution of disease cases and vector populations in relation to environmental and socio-economic factors (Katale & Gemechu, 2023) (Fakro et al., 2019). These tools provide insights into the spatial patterns and hotspots of malaria transmission, which are essential for designing and implementing effective control measures.

Several studies have applied spatial analysis to understand malaria dynamics in different regions. For instance, a study in Ghana used spatial statistics to identify malaria hotspots and their relationship with environmental factors such as temperature, rainfall, and land use (Ekpa et al., 2023) (Adigun et al., 2020). Similarly, in Kenya, researchers used GIS to map the distribution of Anopheles mosquitoes and malaria cases, revealing significant spatial clustering and associations with specific ecological features (Mategula & Gichuki, 2023)(Omumbo et al., 2018).

In Indonesia, spatial analysis of malaria has also gained traction. A study in West Papua utilized remote sensing and GIS to map malaria incidence and associated environmental factors, highlighting the importance of vegetation and water bodies in mosquito breeding (Fadilah et al., 2022)(Mardiana et al., 2018). Another study in Kalimantan explored the spatial-temporal distribution of malaria and its relationship with climatic variables, providing valuable information for predicting malaria outbreaks (Sulasmi et al., 2017)(Rist et al., 2020).

Despite these advances, there is still a need for spatial analyses of malaria in East Java. While some studies have investigated malaria incidence in specific districts or cities within the province, comprehensive spatial analysis encompassing the entire region and integrating multiple Anopheles species is lacking (Indrayana & Ariawan, 2022)(Arwati et al., 2018)(Sundari et al., 2021). Understanding the spatial distribution of both malaria cases and the specific Anopheles species involved is critical for developing tailored and effective control strategies. The current body of research underscores the importance of spatial analysis in understanding malaria transmission and guiding control efforts. However, there are notable gaps, particularly in the context of East Java, Indonesia. While some localized studies provide insights into malaria incidence and vector distribution, there is a lack of comprehensive spatial analysis covering the entire province and incorporating multiple Anopheles species.

Research Design

This study used an observational design with a cross-sectional approach. This method was chosen to allow data collection at one point in time, allowing analysis of the spatial distribution of malaria cases and Anopheles species in the East Java region (Creswell & Clark, 2017). Pendekatan ini sesuai dengan tujuan penelitian untuk memahami pola distribusi spasial dan faktor-faktor lingkungan yang mempengaruhi kejadian malaria di wilayah tersebut.

Research Location

The research was conducted in the province of East Java, Indonesia, which has a wide variety of topography and environments. This location was chosen because of the high incidence of malaria in some areas and the diversity of Anopheles species that act as malaria vectors (Arwati et al., 2018; Snellen, 1988).

Population and Sample

The population of this study was all malaria cases reported in East Java during the period 2021–2023. Malaria case data were collected from the East Java Provincial Health Office and community health centers recorded in the Ministry of Health's malaria information system. In addition, Anopheles mosquito samples were collected from various locations in East Java. Sampling was carried out using the purposive sampling method, where locations with the highest incidence of imported malaria were prioritized (Hasyim et al., 2019).

Data Collection

Malaria case data

Malaria case data was collected from medical records at hospitals and health centres across East Java. Data collected included patient demographic information (age, gender), date of diagnosis, and location of residence.(Elyazar, Gething, et al., 2011; Mahendra, 2024).. This information is recorded in the Ministry of Health's Malaria Information System.

Anopheles Species Data

Data collection on Anopheles mosquitoes was conducted using entomological surveillance methods. The methods used include capturing adult mosquitoes, as well as sampling larvae from aquatic habitats(Hast et al., 2019). Captured mosquitoes were then identified to species using morphological identification keys and molecular methods.(Carter et al., 2018). Existing Anopheles data were obtained from the East Java Health Office Malaria Vector Distribution Data and the research team directly.

Data Analysis

Spatial analyses were conducted using Geographic Information System (GIS) software such as ArcGIS. This analysis included mapping the distribution of malaria cases and Anopheles species, identifying malaria hotspots, as well as clustering analysis to determine areas with high malaria incidence.(Adeola et al., 2015).

Research Ethics

This study has received approval from the Health Research Ethics Committee of the Poltekkes Kemenkes Surabaya. All patient data used in this study were kept confidential and only used for research purposes. Data collection and analysis were conducted in accordance with the principles of research ethics.(Hasyim et al., 2024; Jamrozik et al., 2015; Mayasanti, 2022).

Figure 1 shows that in 2021, although there is a high concentration of malaria cases in certain areas, such as Malang, Banyuwangi and Jember, these cases are imported cases from outside the East Java region. On the other hand, in the East Java region, Anopheles mosquitoes such as Anopheles sundaicus are still found, which are well adapted to coastal habitats. The presence of Anopheles becomes a separate concern when imported cases are found so that it has the potential to become an indiginous case.

In 2022, the distribution pattern of malaria cases still shows a concentration in coastal areas and some valley areas, mountains and some urban areas. However, all cases are imported cases. This emphasises the need for stricter monitoring and control of population travel and migration. The presence of Anopheles species, such as Anopheles maculatus, in rural areas suggests that despite the potential for local transmission, external factors remain a major contributor to the spread of malaria. This suggests that control strategies should include surveillance of the movement of people and potential importation of cases from other areas (Fig. 2).

Figure 3 shows that although the distribution pattern of malaria cases remains consistent with previous years, with hotspots in the same areas, most of the malaria cases reported still come from outside the East Java region. This suggests that despite the presence of malaria mosquito species in East Java, malaria transmission in the region is more influenced by external factors, such as migration and travel from endemic areas. Therefore, malaria control approaches should consider these factors and involve collaboration across regions to prevent the introduction of new cases.

The results of this study show that the spatial distribution of malaria cases in East Java is uneven and tends to be concentrated in certain areas. Malaria hotspots were identified mainly in coastal areas and some areas of valley and rice fields and some cities that have environmental conditions that support the breeding of Anopheles mosquitoes. This finding is in line with previous studies showing that malaria distribution is often correlated with environmental factors such as altitude, rainfall, and land use.(Battle et al., 2019; Wigunawanti, 2022).

This study identified Malang, Trenggalek, and Batu districts as areas with high malaria cases. As did the study by Hinne et al. This is supported by Hinne et al.'s research, (Hinne et al., 2021) who also found that coastal areas with mangrove forests and irrigated rice fields in the region provide ideal habitat for Anopheles mosquitoes. In addition, coastal areas such as Jember, Lumajang and Banyuwngi districts also showed the presence of vectors which can be attributed to high rainfall patterns and the presence of forests that serve as breeding grounds for mosquitoes(Senjarini et al., 2020).

Further analysis revealed that environmental factors such as temperature, humidity, and rainfall play an important role in the spatial distribution of malaria vectors in East Java. Warm temperatures and high humidity create ideal conditions for the life cycle of Anopheles mosquitoes, while high rainfall creates stagnant water used as egg-laying sites(Agyekum et al., 2022). Study by Abiodun et al., (2016) suggests that increasing global temperatures and changing rainfall patterns due to climate change may expand malaria endemic areas in the tropics.

In addition to environmental factors, socioeconomic factors such as population density, access to health services, and education levels also influence malaria distribution. Areas with high population density tend to have a higher risk of transmission due to more intense human-mosquito contact(Krsulovic et al., 2021). In addition, areas with limited access to health services and low education often have higher malaria incidence rates due to a lack of understanding about malaria prevention and delays in seeking treatment(Kigozi et al., 2020).

Spatial distribution analysis showed that Anopheles sundaicus was found more in coastal areas such as Banyuwangi and Jember, while Anopheles maculatus was more dominant in inland areas such as Bondowoso. This distribution reflects the ecological adaptation of each species to different habitats(Hastuty & Natalia, 2020). In addition, variations in the distribution of Anopheles species can also be affected by environmental changes due to human activities such as deforestation and land use change (Agyekum et al., 2021).

The results of this study have several policy implications for malaria control in East Java, including the importance of an ecosystem-based approach to malaria control. Interventions that take into account local environmental conditions such as mosquito habitat and rainfall patterns may be more effective in reducing mosquito populations and malaria transmission(Agyekum et al., 2021). Improving capacity and access to health services in areas with high malaria incidence is critical. Effective health education and outreach programmes can improve community understanding of malaria prevention and the importance of seeking immediate treatment(Sahu et al., 2020). In addition, strengthening health systems to rapidly detect and respond to malaria cases can reduce the spread of the disease(Zhang et al., 2023). Also, there is a need to develop and implement sustainable and adaptive control strategies. Given the presence of insecticide resistance, further research is needed to develop alternative control methods such as the use of new insecticides or biological approaches such as the release of sterile mosquitoes (Hemingway et al., 2016).

This study has several limitations that need to be considered in the interpretation of the results. i.e. the malaria case data used in the analysis may not include all cases occurring in East Java, due to limitations in reporting and access to health services. Data collection on Anopheles species may not cover all potential habitats, so the spatial distribution obtained may not fully represent the mosquito population present(Davies et al., 2019). Also, this analysis does not take into account detailed socioeconomic factors that may influence the risk of malaria transmission. Further studies that combine socioeconomic data with environmental and epidemiological data are needed to gain a more comprehensive understanding of the determinants of malaria transmission in East Java (Guerra et al., 2019).

This study provides important insights into the spatial distribution of malaria cases and Anopheles species in East Java. The results show that the distribution of malaria is influenced by various environmental and socioeconomic factors, as well as showing variation in the distribution of Anopheles species. The policy implications of this study emphasise the importance of ecosystem-based approaches, improved access to health services, and the development of sustainable control strategies. The findings also highlight the need for a multi-sectoral approach and further research to address challenges in malaria control. With a better understanding of the spatial dynamics of malaria and mosquito vectors, control efforts can be more effective and have a positive impact in reducing the burden of malaria in East Java.

Ethical Approval

This study was conducted following the ethical guidelines and regulations, and approval was obtained from the Health Ethics Commission of Poltekkes Kemenkes Surabaya with approval number No.EA/ 2078 /KEPK-Poltekkes_Sby/V/2024

Competing Interests

The authors declare that they have no competing interests.

Authors' Contributions

All authors conceived and designed the study. NN, DN, SW analyzed the data. NN, DN, SW wrote the manuscript. All authors have read and approved the final manuscript.

Funding

This research was supported by Poltekkes Kemenkes Surabaya. The funding body had no role in the design of the study, collection, analysis, interpretation of data, or in writing the manuscript.

Availability of Data and Materials

The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

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You are reading this latest preprint version

Spatial Analysis of Malaria Cases and Anopheles Species in East Java Region, Indonesia

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Abstract

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Introduction

Methods

Research Design

Research Location

Population and Sample

Data Collection

Malaria case data

Anopheles Species Data

Data Analysis

Research Ethics

Results

Discussion

Conclusion

Declarations

References

Status:

Version 1