Environmental Factors to Malaria Incidence : A Literature Review

Malaria remains a major public health concern in Indonesia, particularly due to its high mortality rate among children under five, accounting for approximately two-thirds of all cases. The disease is transmitted by female Anopheles mosquitoes, which carry the Plasmodium parasite. In 2019, malaria caused 409,000 deaths globally, with 229 million cases reported, particularly in remote areas with poor access to healthcare, commonly in low-income countries. This literature review highlighted the environmental risk factors contributing to malaria incidence, based on studies from 24 scientific journals using data from the Sinta and Scopus databases. The study identified key environmental factors, including physical, chemical, biological, and socio-cultural elements, with the most significant risk linked to vector breeding sites. Among the reviewed articles, 62.5% (15 out of 24) found a statistically significant association between the presence of mosquito breeding sites and malaria incidence. Additional risk factors included the use of mosquito nets, housing conditions (specifically wall density), and nighttime outdoor activities. Effective malaria control measures require addressing these environmental factors, as they play a crucial role in the disease’s transmission. Strategies to disrupt the transmission cycle include eliminating mosquito breeding sites, applying larvicides to stagnant water, cleaning vector resting areas, promoting the use of insecticide-treated nets, and implementing Indoor Residual Spraying (IRS). A community-based, integrated approach to environmental management is essential to reducing malaria transmission and controlling its spread in affected regions.

INTRODUCTION

Malaria is caused by the Plasmodium parasite carried by anopheles mosquitoes through salivary glands when they bite in search of blood for the maturation of female mosquito eggs. Five types of species infect humans, specificallyPlasmodium ovale, Plasmodium malariae, Plasmodium falciparum, Plasmodium vivax,andPlasmodium knowlesi¹¹. Plasmodium lives and multiplies in human red blood cells.P. falciparumis highly feared because it is responsible for 80% morbidity and 90% mortality.Anophelessp. mosquitoes undergo complete metamorphosis in their life cycle from eggs, larvae, pupae, to adults²².

Malaria's main symptom is fever, which can be periodic depending on the type of the malaria. Other symptoms include headache, nausea, vomiting, diarrhea, aches and muscle pain³³.

According to the WHO assessment of malaria cases in 2022, there are expected to be 249 million cases in 85 countries and regions where malaria is endemic, which is 5 million more cases than in 2021⁴⁴.

Eliminating the malaria epidemic is one of the Sustainable Development Goals (SDGs) and a crucial metric that needs to be met by 2030. According to World Malaria Day 2023 in Indonesia, 1,412 deaths from 811,636 new cases of malaria in 2021 occurred in Papua Province, and 89% of malaria cases occurred in the whole country of Indonesia⁵⁵. Malaria causes considerable economic losses, so it is still a problem in Indonesia. Although malaria control efforts have made progress in the past decade, 2022 saw an increase.

Malaria cases in Indonesia increased to 1.6 per 1,000 people in 2022, with a parasite's annual incidence of 1.6 per 1,000 people. API indicators are used to classify malaria endemicity in Indonesia, where eastern Indonesia includes areas with high malaria cases, Kalimantan, Sulawesi, and Sumatra include areas with moderate malaria cases, and Java and Bali include areas with low malaria cases⁶⁶.

Environmental factors have a significant impact on malaria transmission. Environmental factors are all external conditions and influences that affect the life and development of organisms such as physical environment such as temperature, humidity, rain, altitude, wind, sunlight, water currents, wall conditions, the presence of wire gauze on house vents, ceilings, and hanging clothes, biological environments such as the presence of standing water, breeding grounds, livestock pens, larva-eating fish, chemical environments such as pH and salinity, as well as socio-cultural environments like the application of mosquito netting, the habit of not wearing long sleeves, the use of insect repellent, various human activities such as dam construction, road construction, mining and the construction of new settlements or transmigration⁷⁷. This article reviews the environmental factors that can cause malaria, including physical, chemical, biological, social, and cultural environments.

OVERVIEW

The purpose of this literature review was to obtain interesting theoretical studies for future research by systematically identifying and analyzing malaria incidence according to the criteria selected in the topic⁸⁸. The data source used was based on scientific publication literature according to the topic in this study obtain from some publication databases (Sinta and Scopus).

This article reviewed 24 articles that have been filtered and analyzed based on objectives, topic suitability, variables used, and the results of each article. The criteria used in finding the desired article were research on the determinants of malaria incidence, especially environmental factors, and articles published between 2018 and 2022.

This literature review was related to previous research on environmental factors that influence malaria incidence in Indonesia and other nations. This literature review article's goal was to summarize some of the research that had been conducted on environmental factors and had potentials to examine in detail some environmental factors that affected the incidence of malaria. Based on the collected data, the environmental factors that had the most potential for malaria transmission could be identified so that the control stage could be carried out appropriately according to the target.

According to the data collected from multiple articles, there was a relation between environmental variables and malaria incidence. The environmental factors identified in this review were breeding places, home wall condition, the presence of ceilings, getting used to going out late at night, the presence of wire gauze, bushes, livestock sheds,resting places, the use of mosquito nets, repellent, knowledge, work, treatment, counseling, the presence of puddles, the practice of hanging clothes and going to endemic areas.

The breeding place was the dominant factor that often found from the 24 articles collected. Fifteen articles, the articles number 1, 3, 4, 7, 9, 13, 14, 15, 16, 17, 18, 20, 21, 23 and 24, proved that anopheles mosquito breeding sites had a risk of malaria incidence. The methods used were case-control, with as many as 7 articles, and cross-sectional, with as many as 4, 1, and 1 observational article. Seven articles (number 7,8,12,15,18,21 and 22) stated that the habit of using mosquito nets, home wall condition, and the habit of leaving the house at night were related to malaria. Five articles found that resting places and the existence of livestock sheds were related to the incidence of malaria. There were four articles that found connection between wire gauze's existence and the existence of ceilings and the use of mosquito repellent, and one article found a relationship between malaria and a history of traveling to endemic areas. The articles reviewed are presented in Table 1 :

No.	Researcher/Year	Method	Variable	Result
1	Resiany