Factors associated with malaria infection in under-5 children in Papua Province, Indonesia: an observational study

Abstract

Objectives

Malaria remains a serious public health challenge in tropical and subtropical regions, including Indonesia. Children under 5 years old face particular risk of contracting malaria due to low immunity. We examined potential factors associated with malaria infection among under-5 children in Papua Province, Indonesia.

Methods

The study utilized secondary data from Indonesia Basic Health Research 2018. Multistage random sampling was employed, from the province level to census blocks (CBs). In Papua Province, interviews were conducted in 928 CBs. All 2,745 under-5 children were selected. The dependent variable was laboratory-confirmed malaria positivity; independent factors included residential area, socioeconomic characteristics, and behaviors such as sleeping under an insecticide net impregnated ≤3 years ago and the use of ventilation barriers. We also examined the conditions of the bedroom, kitchen, and living room according to the frequency of window-opening, proportion of ventilation area to the floor, and radiance.

Results

Not sleeping under an insecticide net impregnated within the last 3 years (adjusted odds ratio [aOR], 0.518; 95% confidence interval [CI], 0.391–0.685; p<0.001); having a kitchen without windows (aOR, 0.491; 95% CI, 0.285–0.844; p=0.01); rarely opening the living room window (aOR, 2.804; 95% CI, 1.232–6.383; p=0.01), and having a windowless living room (aOR, 3.027; 95% CI, 1.369–6.696; p=0.01) displayed significant relationships with malaria infection among under-5 children.

Conclusion

Not using an insecticide-treated net impregnated ≤3 years ago, along with opening the living room window daily and having a kitchen without windows, appear preventive of malaria infection among under-5 children.

Graphical abstract

Introduction

Malaria represents a serious public health challenge in tropical and subtropical regions, impacting hundreds of millions of individuals worldwide. Approximately 3.2 billion people are at risk of contracting malaria globally, with pregnant women and children under the age of 5 being particularly vulnerable [1]. Indonesia faces a dual burden of disease characterized by a rise in noncommunicable diseases alongside persistent infectious diseases such as tuberculosis, human immunodeficiency virus/acquired immunodeficiency syndrome, and malaria [2]. In 2018, the reported prevalence of malaria in Indonesia was 0.37%, with the disease being endemic in the eastern part of the country [3]. Of the malaria cases recorded in Indonesia in 2019, 57% were attributed to Plasmodium falciparum, 35% to Plasmodium vivax, 1% to Plasmodium malariae, and 7% to multispecies infections. Very few cases of Plasmodium ovule were recorded [4].

Indonesia has made considerable strides in its efforts to eliminate malaria, as demonstrated by the Ministry of Health of the Republic of Indonesia’s Decree No. 293 in 2011 [5]. The strategies employed include indoor residual spraying, the provision of insecticide-treated nets to vulnerable groups such as children under 5 and pregnant women, treatment of malaria with artemisinin combination therapy, the use of rapid diagnostic tests in remote areas, and the implementation of early detection through laboratory testing followed by prompt treatment [5]. Indonesia has set a goal to eliminate malaria by 2030. Accordingly, the Ministry of Health of the Republic of Indonesia awards certificates of malaria elimination to districts/municipalities that achieve an annual parasite incidence of less than 1 per 1,000 at-risk individuals and have had no local malaria transmission for the preceding 3 years [5]. Since the first certificate of malaria elimination was presented to the Kepulauan Seribu district in Jakarta Province in 2013, a total of 405 (78.3%) of the 514 districts/municipalities had received certificates by June 2023 [6].

The regions of eastern Indonesia that are endemic for malaria include the provinces of Papua, West Papua, Maluku, and East Nusa Tenggara [7,8]. In the Basic Health Research data, Papua Province had the highest malaria prevalence, with rates of 17.5% in 2013 [9] and 12.7% in 2018 [3]. Despite the decline in malaria cases in Papua Province, the disease remains a particular threat to children under 5 years old, who have relatively low malaria immunity [10,11].

Papua Province is characterized by its diverse geography and topography, including coastal lowlands, dense highland rainforests, expansive wetland river basins, and high mountain ranges [12,13]. This geographic diversity leads to a wide variation in population distribution. The geography of Papua markedly influences malaria transmission. Many villages are nestled in rugged landscapes with challenging terrain, resulting in many isolated communities [13]. The most common breeding sites for all Anopheles malaria vector species are natural or human-made pools, and the presence and development of these breeding sites in Papua vary both geographically and seasonally [14]. The dominant malaria vectors in Papua Province are Anopheles punctulatus species (An. farauti, An. koliensis, and An. punctulatus) [15].

The risk of malaria exposure is influenced by individual behavior and location during night time [16,17]. Those who work in forests at night or who are frequently outdoors face an increased risk of contact with malaria vectors. Repeated exposure to these vectors can lead to the development of immunity, resulting in asymptomatic malaria. However, higher parasite density may lead to symptomatic malaria. Fever is a common symptom of malaria, often occurring due to the rupture of infected erythrocytes. High levels of parasitemia can trigger severe malaria, which is associated with increased mortality. In areas prone to malaria transmission, many infants and young children exhibit reduced hemoglobin concentrations [18,19]. Malaria induces hemolysis of both infected and uninfected erythrocytes, slowing the recovery from anemia. Furthermore, children under 5 are susceptible to infectious conditions such as diarrhea, measles, bronchopneumonia, and tuberculosis [20–22].

Studies have demonstrated links between socioeconomic factors, preventive behaviors, and malaria risk. Socioeconomic characteristics associated with malaria in children under 5 years old include little or no formal maternal education, poverty or low household income, rural area of residence, age of the child, and a household size of 6 or more residents [23,24]. Behavioral factors that influence malaria risk include the use of insecticide-treated bed nets and time spent outdoors at night [25–27]. Furthermore, the structure of a home has been shown to affect malaria risk, encompassing factors such as the materials used in construction, residing in a house as it is built, and the availability of toilet facilities, clean water, and electricity [23,28,29].

In Papua Province, relatively high rates of malaria-related morbidity have been reported among under-5 children. A study conducted in Papua between 2004 and 2013 revealed that, within a 1-year period, 48.4% (7,620) of the 15,716 children under 5 years old who had presented with malaria exhibited recurrence. A total of 266 children (1.7%) died within 1 year of symptom onset, with 129 deaths (48.5%) occurring within the first 30 days and 137 deaths (51.5%) occurring between 31 and 365 days. No significant difference was observed in the risk of death between patients infected with P. vivax and those with P. falciparum [30]. Given the high morbidity and mortality rates of malaria in children under 5 in Papua, it is crucial to investigate factors associated with the incidence of malaria in this region. This study was conducted to identify factors linked to malaria infection among children under 5 years old in Papua Province.

Materials and Methods

This study utilized secondary cross-sectional data from the Indonesia Basic Health Research (Riset Kesehatan Dasar, Riskesdas), which was conducted by the National Institute of Health Research and Development (NIHRD) under the Ministry of Health, Republic of Indonesia, in 2018. The Riskesdas instrument has been a regular national household health survey since 2007 and was also conducted in 2010 and 2013.

The study employed multistage systematic random sampling for respondent selection. The first step was to identify census blocks (CBs) as the primary sampling units (PSUs). In the second stage, we applied a probability proportional to size (PPS) design to select a CB from each PSU. From the 720,000 CBs in the master frame obtained from the 2010 Indonesian Population Survey by the Indonesian Central Bureau of Statistics, 180,000 CBs were chosen as the sampling frame. This selection used the PPS method and was designed to represent urban and rural areas within each sub-district at the district level. For the national household basic health survey, 30,000 CBs were selected from the initial 180,000. The sample included all household members who had lived in the household for at least 6 months and who were involved in food management within the selected households across all 34 provinces of Indonesia [3].

Papua is one of these 34 provinces, encompassing 29 districts/cities out of a total of 514 nationwide. The 2018 National Household Health Survey (Riskesdas) set a sampling target for Papua Province of 1,104 CBs. Of these, 930 CBs were successfully visited, yielding a response rate of 84.24%. Among the visited CBs, interviews were conducted for 928 (response rate, 99.78%). The goal of the survey was 11,040 households; 9,050 households were reached (response rate, 81.97%) and, of those, 7,700 households were interviewed (response rate, 85.08%). In total, 31,307 individuals were visited, and interviews were completed for 24,625 individuals (response rate, 78.66%). Of the 24,625 people interviewed in Papua Province, 2,745 were under-5 children, representing 11.15% of the total [3].

Participants

The analysis targeted children under 5 years of age (0–59 months) in Papua Province. Data on the respondents were collected through interviews with parents or individuals knowledgeable about the children’s health status. Individual health data were gathered through structured interviews conducted by enumerators with a background in health education, who had received training prior to data collection. Data pertaining to the health condition of the household were obtained through observations made by these trained enumerators, utilizing household questionnaires. The study included a total of 2,745 children under the age of 5.

Instruments

The study utilized structured interviews with individual questionnaires as instruments. Before the interview, respondents were required to sign an informed consent form, confirming their understanding of the study’s purpose and their voluntary participation. For the children included in the study, their parents provided signed informed consent. Information regarding the condition of air circulation and the level of light in the bedroom, kitchen, and living room was gathered through observations made by trained enumerators using household questionnaires.

Variables

The dependent variable in this study was the incidence of malaria infection among children under 5 years of age. Specifically, we determined whether—either in the past month or during the previous 1 to 12 months—the respondents’ children had been diagnosed with malaria following blood testing conducted by health professionals (doctors, nurses, or midwives). Initially, respondents were queried about whether their children had undergone blood sampling for malaria testing by health professionals within the same time frames. If the response was affirmative, a follow-up question was posed to ascertain whether the children were diagnosed with malaria based on the results of the blood examination.

Independent factors included socioeconomic and demographic characteristics, namely area of residence (urban or rural), sex (female or male), number of household members (continuous), and child status (the respondent’s own children or others). Additionally, behaviors such as sleeping under an insecticide-impregnated within the last 3 years or less (yes or no), the presence of a home ventilation screen barrier (yes or no), and various characteristics of a healthy house in terms of air circulation and light exposure were considered. Air circulation and light exposure in the bedroom, kitchen, and living room were assessed based on the frequency with which windows are opened (every day, rarely, or no window), the ratio of ventilation area to floor space (10% of the floor, less than 10% of the floor, or no ventilation), and whether the room’s light exposure was sufficient. Maintaining healthy households with good air quality is crucial for developing effective strategies to prevent malaria [31].

Conceptual Framework

Malaria in under-5 children

The variables consist of (1) socioeconomic factor (urban/rural area, number of family members, age, sex, respondents’s own children/other), (2) preventive behavior of sleeping under an insecticide net impregnated within the last 3 years, (3) vantilation screen barrier in the home, and (4) condition of the bedroom, kitchen, and living room regarding (a) window opened, (b) the proportion of ventilation size to floor, and (c) the light/radiance affect malaria infection, particularly in under-5 years children. They are at risk of malaria infection because of a relatively lower malaria immunity.

Data Analysis

The dependent variable in this study was the binary outcome of malaria infection diagnosis, determined through blood examination by health workers (doctors, nurses, or midwives). The independent variables included: (1) socioeconomic or demographic factors such as living area, number of household members, sex, and child status; (2) preventive behavior, specifically the use of insecticide-treated nets that were impregnated no more than 3 years ago; (3) barriers, such as the presence of house ventilation screens; and (4) housing conditions, which encompassed the bedroom, kitchen, and living room, evaluated based on (a) the frequency with which windows were opened, (b) the ratio of ventilation area to floor size, and (c) the level of light/radiance in the room. Bivariate analysis was conducted to assess the relationship between each independent factor and malaria infection among under-5 children. All independent variables that were associated with malaria infection in this age group (p<0.2) were included in the multivariate analysis. This analysis was performed using binary logistic regression. IBM SPSS ver. 21.0 (IBM Corp.) was utilized for data analysis.

Ethical Consideration

Ethical approval for RISKESDAS 2018 was obtained from the Ethical Committee of Health Research at the NIHRD, Ministry of Health, Republic of Indonesia, under the reference number LB.02.01/2/KE.267/2017.

Results

In 2018, the prevalence of malaria among children under 5 in Papua Province was 10.8%. Socioeconomically, most of these children (75.2%) resided in rural areas, with a mean family size of 5.83 members. Slightly more than half of these children were boys (51.6%), and the majority (85.6%) were the biological children of the respondents.

Table 1 indicates that just over half (51.6%) of the under-5 children slept under an insecticide-treated net that was impregnated 3 years ago or less. Regarding mosquito barriers, the majority (77.7%) of houses lacked ventilation screens. In terms of maintaining a healthy household environment, the data revealed that for bedrooms, windows were opened daily in 49.0% of cases, 41.1% had ventilation that is at least 10% of the floor area, and 61.5% received adequate light. Regarding kitchens, windows were opened daily in 45.1% of homes, 45.5% met the minimum 10% ventilation-to-floor area ratio, and 59.6% had sufficient light. For living rooms, 51.7% had windows that were opened daily, 46.3% had sufficient ventilation, and 64.7% benefitted from adequate light.

Table 1.

Sociodemographic factors, insecticide-treated net usage, ventilation screen barriers, and housing conditions related to malaria infection among children under 5 in Papua Province, Indonesia

Variable	Value
Malaria diagnosis
Negative	2,449 (89.2)
Positive	296 (10.8)
Socioeconomics and demographics
Area of residence
Urban	682 (24.8)
Rural	2,063 (75.2)
No. of household members	5.83±2.34
Sex
Female	1,329 (48.4)
Male	1,416 (51.6)
Child status
Respondent’s own child	2,349 (85.6)
Others	396 (14.4)
Preventive behavior
Sleeps under insecticide net impregnated ≤3 years ago
Yes	1,331 (48.5)
No	1,414 (51.5)
Barrier
Ventilation screen
Yes	611 (22.3)
No	2,134 (77.7)
Health conditions of home
Bedroom
Bedroom window
Opened every day	1,345 (49.0)
Rarely opened	601 (21.9)
No window	612 (22.3)
Not applicable	187 (6.8)
Bedroom ventilationa)
Ventilation ≥10% of the floor	1,051 (41.1)
Ventilation <10% of the floor	737 (28.8)
No ventilation	770 (30.1)
Bedroom radiancea)
Sufficient	1,573 (61.5)
Insufficient	985 (38.5)
Kitchen
Kitchen window
Opened every day	1,239 (45.1)
Rarely opened	426 (15.5)
No window	857 (31.2)
Not applicable	223 (8.1)
Kitchen ventilationb)
Ventilation ≥10% of the floor	961 (38.1)
Ventilation <10% of the floor	665 (26.4)
No ventilation	896 (45.5)
Kitchen radianceb)
Sufficient	1,504 (59.6)
Insufficient	1,018 (40.4)
Living room
Living room window
Opened every day	1,419 (51.7)
Rarely opened	493 (18.0)
No window	609 (22.2)
Not applicable	224 (8.2)
Living room ventilationc)
Ventilation ≥10% of the floor	1,168 (46.3)
Ventilation <10% of the floor	600 (23.8)
No ventilation	753 (29.9)
Living room radiancec)
Sufficient	1,632 (64.7)
Insufficient	889 (35.3)
Total	2,745 (100.0)

Data are presented as n (%) or mean±standard deviation.

^a)For 187 under-5 children, the house had no separate bedroom.

^b)For 223 under-5 children, the house had no separate kitchen.

^c)For 224 under-5 children, the house had no separate living room.

Table 2 presents the bivariate analysis. Regarding socioeconomics and demographics, sex (crude odds ratio [cOR], 0.960; 95% confidence interval [CI], 0.754–1.222) was not significantly associated with malaria infection among under-5 children. However, a rural area of residence, the number of household members, and child status were associated with malaria infection in this age group, as evidenced by p-values less than 0.2.

Table 2.

Factors independently associated with malaria infection among children under 5 in Papua Province, Indonesia

Variable	Malaria-negative	Malaria-positive	cOR (95% CI)	p
Socioeconomics and demographics
Area of residence
Urban	599 (87.8)	83 (12.2)
Rural	1,850 (89.7)	213 (10.3)	0.831 (0.634–1.088)	0.18
No. of household members
1
More than 1 (continuous)			1.070 (1.021–1.122)	0.01
Sex
Female	1,183 (89.0)	146 (11.0)
Male	1,266 (89.7)	150 (10.6)	0.960 (0.754–1.222)	0.74
Child status
Respondent’s own child	2,106 (90.3)	225 (9.7)
Others	322 (81.9)	71 (18.1)	2.064 (1.542–2.762)	<0.001
Preventive behavior
Sleeps under insecticide net impregnated ≤3 years ago
Yes	1,147 (86.2)	184 (13.8)
No	1,302 (92.1)	112 (8.1)	0.540 (0.418–0.687)	<0.001
Barrier
Ventilation screen
Yes	521 (85.3)	90 (14.7)
No	1,928 (90.3)	206 (9.7)	0.615 (0.474–0.807)	<0.001
Health conditions of home
Bedroom
Bedroom window
Opened every day	1,147 (85.3)	198 (14.7)
Rarely opened	538 (89.5)	63 (10.5)	10.588 (3.350–33.461)	<0.001
No window	580 (94.8)	32 (5.2)	7.182 (2.229–23.147)	<0.001
Not applicable	184 (98.4)	3 (1.6)	3.438 (1.024–11.179)	0.05
Bedroom ventilationa)
Ventilation ≥10% of the floor	883 (84.0)	168 (16.0)
Ventilation <10% of the floor	663 (90.0)	74 (10.0)	2.682 (1.931–3.725)	<0.001
No ventilation	719 (93.4)	51 (6.6)	1.574 (1.085–2.283)	0.02
Bedroom lighta)
Sufficient	1,352 (86.0)	221 (14.0)
Insufficient	913 (92.7)	72 (7.3)	0.482 (0.365–0.638)	<0.001
Kitchen
Kitchen window
Opened every day	1,068 (86.2)	171 (13.8)
Rarely opened	392 (92.0)	34 (8.0)	1.719 (1.046–2.826)	0.03
No window	785 (91.6)	72 (8.4)	0.931 (0.518–1.674)	0.81
Not applicable	204 (91.5)	19 (8.5)	0.985(0.581–1.670)	0.96
Kitchen ventilationb)
Ventilation ≥10% of the floor	811 (84.4)	150 (15.6)
Ventilation <10% of the floor	603 (90.7)	62 (9.3)	2.365 (1.740–3.213)	<0.001
No ventilation	831 (92.7)	65 (7.3)	1.315 (0.914–1.891)	0.14
Kitchen lightb)
Sufficient	1,303 (86.6)	201 (13.4)
Insufficient	942 (92.5)	76 (7.5)	0.523 (0.37–0.690)	<0.001
Living room
Living room window
Opened every day	1,215 (85.6)	204 (14.4)
Rarely opened	438 (88.8)	55 (11.2)	1.713 (1.057–2.775)	0.03
No window	592 (97.2)	17 (2.8)	1.281 (0.748–2.194)	0.37
Not applicable	204 (91.1)	20 (8.9)	0.293 (0.151–0.570)	<0.001
Living room ventilationc)
Ventilation ≥10% of the floor	979 (83.8)	189 (16.2)
Ventilation <10% of the floor	550 (91.7)	50 (8.3)	3.736 (2.593–5.383)	<0.001
No ventilation	716 (95.1)	37 (4.9)	1.759 (1.134–2.730)	0.01
Living room lightc)
Sufficient	1,402 (85.9)	230 (14.1)
Insufficient	843 (94.8)	46 (5.2)	0.333 (0.240–0.462)	<0.001
Total	2,428 (88.4)	296 (11.6)

cOR, crude odds ratio; CI, confidence interval.

^a)For 187 under-5 children, the house had no separate bedroom.

^b)For 223 under-5 children, the house had no separate kitchen.

^c)For 224 under-5 children, the house had no separate living room.

Interestingly, not sleeping under an insecticide-impregnated within the last 3 years or (cOR, 0.540; 95% CI, 0.418–0.687) and the absence of a ventilation screen barrier (cOR, 0.615; 95% CI, 0.474–0.807) appeared preventive of malaria infection among under-5 children.

Various conditions of the bedroom, kitchen, and living room—including window opening, ventilation, and light exposure—were significantly associated with malaria incidence in children under 5 years old. Regarding kitchens, window opening, ventilation, and radiance were associated with malaria infection among this age group (p<0.2). Similarly, the characteristics of living room windows, ventilation, and light exposure were significantly linked to malaria infection in children under 5.

Table 3 presents the results of the multivariate analysis, indicating nonsignificant associations (p>0.05) of rural area of residence (adjusted odds ratio [aOR], 1.038; 95% CI, 0.752–1.433), the number of household members (aOR, 1.008; 95% CI, 0.952–1.067), and child status (aOR, 1.341; 95% CI, 0.939–1.917) with malaria infection among children under 5. However, not sleeping under an insecticide-treated net was significantly associated with a reduced risk of malaria infection in this age group (aOR, 0.518; 95% CI, 0.391–0.685; p<0.001). Conversely, the presence of ventilation screens in houses did not show a significant association with malaria infection among children under 5 (aOR, 0.854; 95% CI, 0.626–1.165; p=0.32).

Table 3.

Multivariate analysis of factors associated with malaria infection among children under 5 in Papua Province, Indonesia

Variable	β	aOR (95% CI)	p
Socioeconomic and demographics
Area of residence
Urban		Ref.
Rural	0.038	1.038 (0.752–1.433)	0.82
Number of household members
1		Ref.
More than 1 (continuous)	0.008	1.008 (0.952–1.067)	0.79
Child status
Respondent’s own child		Ref.
Others	0.294	1.341 (0.939–1.917)	0.11
Preventive behavior
Sleeps under insecticide net impregnated ≤3 years ago
Yes		Ref.
No	−0.658	0.518 (0.391–0.685)	<0.001
Barrier
Ventilation screen
Yes		Ref.
No	−0.158	0.854 (0.626–1.165)	0.32
Health conditions of home
Bedroom
Bedroom window
Opened every day		Ref.
Rarely opened	0.475	1.608 (0.788–3.283)	0.19
No window	0.431	1.539 (0.774–3.060)	0.22
Bedroom ventilation
Ventilation ≥10% of the floor		Ref.
Ventilation <10% of the floor	−0.050	0.951 (0.430–2.103)	0.90
No ventilation	−0.063	0.939 (0.465–1.895)	0.86
Bedroom light
Sufficient		Ref.
Insufficient	0.083	1.087 (0.629–1.878)	0.77
Kitchen
Kitchen window
Opened every day		Ref.
Rarely opened	−0.368	0.692(0.420–1.140)	0.15
No window	−0.712	0.491 (0.285–0.844)	0.01*
Kitchen ventilation
Ventilation ≥10% of the floor		Ref.
Ventilation <10% of the floor	0.497	1.644 (0.861–3.140)	0.13
No ventilation	0.233	1.263 (0.717–2.224)	0.42
Kitchen light
Sufficient		Ref.
Insufficient	0.093	1.097 (0.663–1.816)	0.72
Living room
Living room window
Opened every day		Ref.
Rarely opened	1.031	2.804 (1.232–6.383)	0.01*
No window	1.108	3.027 (1.369–6.696)	0.01*
Living room ventilation
Ventilation ≥10% of the floor		Ref.
Ventilation <10% of the floor	0.160	1.174 (0.543–2.539)	0.68
No ventilation	−0.201	0.818 (0.394–1.697)	0.59
Living room light
Sufficient		Ref.
Insufficient	−0.246	0.782 (0.433–1.412)	0.42
Constant	−2.213	0.109	<0.001

aOR, adjusted odds ratio; CI, confidence interval; ref., reference.

The characteristics of bedroom windows, ventilation, and light exposure were not significantly associated with malaria infection among children under 5 years old. Regarding kitchens, the presence of kitchen windows that were rarely opened was not significantly associated with malaria infection (aOR, 0.692; 95% CI, 0.420–1.140; p=0.15). However, the absence of a kitchen window was significantly linked to a reduced risk of malaria infection among these children (aOR, 0.491; 95% CI, 0.285–0.844; p=0.01). In the multivariate analysis, neither kitchen ventilation nor the level of light in the kitchen was significantly associated with malaria infection in this age group.

For the living room, both the presence of windows that rarely opened (aOR, 2.804; 95% CI, 1.232–6.383; p=0.01) and the lack of windows (aOR, 3.027; 95% CI, 1.369–6.696; p=0.01) were significantly associated with malaria infection among under-5 children. However, neither the ventilation nor the lighting of the living room was significantly associated with infection in the multivariate analysis.

Discussion

Malaria is endemic in eastern Indonesia, with Papua Province exhibiting the highest prevalence among the eastern provinces [8,9]. As part of its goal to eliminate malaria by 2030, Indonesia has intensified its efforts to reduce the prevalence of the disease, particularly among high-risk groups such as children under 5 years old [32]. Children under 5 face a higher risk of malaria due to their less developed immunity compared to adults. In areas where malaria is endemic, children become most susceptible to infection between the ages of 4 to 6 months, as maternally transferred antibodies diminish [33]. Subsequently, they start to develop their own antibodies through repeated exposure to the infection [34].

Following the bite of an infected female Anopheles mosquito, the Plasmodium parasite responsible for malaria enters a child’s bloodstream and rapidly migrates to the liver, where it develops into schizonts. As these schizonts mature, they rupture and release merozoites into the bloodstream, which then invade red blood cells. The infected red blood cells eventually burst, further spreading the parasites and gametocytes into the bloodstream, causing febrile episodes characteristic of malaria. This process continues over an incubation period of approximately 7 to 30 days, depending on the Plasmodium species, during which the child’s low immunity to malaria intensifies the severity of the disease [35,36]. If not treated promptly, the infection can lead to severe complications, including anemia and cerebral malaria, which are particularly perilous for young children due to their underdeveloped immune systems. Repeated exposure of the immune system to infection can lead to modifications, such as the upregulation of interferon-inducible genes and increased activation of neutrophils and CD8+ T cells; these changes may alter the course and severity of the disease [37]. The high mortality rate in this vulnerable age group underscores the critical importance of timely diagnosis and intervention, as delays can have life-threatening consequences [38]. Additionally, anemia among children under 5, often associated with malaria, can significantly contribute to developmental delays in motor skills, communication, and social interactions among affected children [39].

Malaria transmission remains high in endemic regions. As part of the strategy to eliminate the disease, the Ministry of Health in Indonesia distributes insecticide-treated nets to high-risk populations in these areas, specifically targeting children under 5 years old and pregnant women [40]. Insecticide-impregnated nets can repel mosquitoes [38,41], and we cannot dismiss the potential protective effect of nets impregnated with insecticide within the last 3 years. The insecticidal activity of these nets generally diminishes after 3 years, resulting in a gradual decline in their effectiveness. Expanding the coverage of insecticide-impregnated nets across high-risk groups is expected to reduce malaria transmission by offering protection against mosquito bites [42]. However, this study suggested that not sleeping under a net impregnated recently (3 years ago or less) was significantly associated with lower risk (aOR, 0.518; 95% CI, 0.391–0.685) of malaria infection in children under 5 years old. The Basic Health Research 2018 only assessed the use of insecticide nets that were impregnated within the last 3 years as a binary variable (yes or no). Consistent use of these nets is crucial for preventing contact between humans and malaria vectors, as intermittent use still poses a risk of mosquito bites [25,26].

The presence of ventilation screens in houses can also affect the risk of malaria. A ventilation screen serves as a barrier to keep mosquitoes from entering the home. However, in this study, the absence of a ventilation screen was preventive against malaria among under-5 children, although this relationship was not significant. This finding may be attributed to improper maintenance of the screens, such as the presence of holes that could permit mosquito entry. Ventilation screens in homes can be effective in preventing malaria when they are properly used and maintained [43].

Improved housing structures that utilize solid materials have been associated with a decrease in malaria incidence in Africa [44]. These materials, such as metal or wood, help prevent mosquitoes from entering homes. In Papua Province, most houses feature metal roofs and wooden walls and floors, according to data from the Statistics Central Bureau of Papua Province in 2018 [45]. The Basic Health Research of 2018 evaluated various factors, including home air circulation and light exposure, that contribute to a healthier living environment. Poor air circulation and inadequate lighting create favorable conditions for mosquitoes and malaria vectors to enter and find hiding places, such as under tables or beds, or behind cupboards [41]. The research also examined the conditions of bedrooms, kitchens, and living rooms in terms of air circulation and light exposure. These factors are influenced by how often the windows in these rooms are opened, the ratio of ventilation size to floor area, and the level of light in the room [41]. Proper air circulation ensures that the air in the rooms is refreshed and clean. Additionally, sufficient light exposure prevents a room from becoming dark and humid. Conversely, inadequate air circulation and low light levels can contribute to a warm, humid, and dark environment, potentially increasing the risk of fungal growth or infective disease.

The peak biting time for malaria vectors occurs from dusk to night, with the highest activity at night [45]. This study examined the associations between housing conditions (in the living room, kitchen, and bedroom) and malaria infection in children under 5 years of age.

Living Room Conditions

Windows

Living rooms with windows that are rarely opened (aOR, 2.804; 95% CI, 1.232–6.383) or that have no windows at all (aOR, 3.027; 95% CI, 1.369–6.696) were associated with a significantly increased risk of malaria.

Ventilation

Low ventilation in living rooms was associated with a slightly elevated risk of malaria. Conversely, the absence of ventilation exhibited a protective effect. However, neither finding reached statistical significance.

Radiance

Insufficient living room illumination was associated with a reduced risk of malaria, although the association was not statistically significant. Children under the age of 5

often spend time in living rooms during the evening hours. This may explain the heightened risk of malaria associated with windows, as they could allow more mosquitoes to enter and remain in the room.

Windows

Kitchens with windows that are rarely opened (aOR, 0.692; 95% CI, 0.420–1.140) or that have no windows at all (aOR, 0.491; 95% CI, 0.285–0.844) were associated with a decreased risk of malaria. However, only the complete absence of windows represented a statistically significant finding.

Ventilation

Kitchens with low or no ventilation were associated with an increased risk of malaria; however, the results were not statistically significant.

Radiance

Insufficient kitchen lighting was associated with a marginally increased risk of malaria, although this finding was not significant. The protective effect of windowless kitchens may stem from the heat generated during cooking, creating an environment inhospitable for mosquitoes.

Bedroom Conditions

Windows

Bedrooms with windows that are rarely opened, or those with no windows at all, were associated with an increased risk of malaria; however, these associations were not statistically significant.

Ventilation

Bedrooms with low ventilation (less than 10% of the floor area) or no ventilation appeared to offer protection against malaria. However, these results were not statistically significant.

Radiance

Insufficient bedroom illumination was associated with a slightly increased risk of malaria, but this finding was not significant.

A healthy home is characterized by good air circulation, which ensures clean air and prevents the accumulation of particles or pollutants. Infrequently opened windows and living rooms without windows can lead to poor air circulation. Such conditions may increase the risk of infections, including fungal and upper respiratory infections [46,47]. In this study, for living rooms, both rarely opened windows and the absence of windows were significantly associated with malaria among children under 5. These conditions may create favorable hiding places for mosquitoes. Conversely, kitchens without windows appear to significantly reduce the risk of malaria among this age group. It is possible that the higher temperatures in windowless kitchens create an environment that is unfavorable for mosquitoes. Regularly opening windows in the living room has been shown to prevent mosquitoes from finding refuge [31].

Malaria is endemic in areas with low socioeconomic status, as well as rural regions [23,24,48]. In rural areas, the presence of vector breeding sites such as rivers, streams, and stagnant water bodies contributes to increased malaria transmission [24]. Conversely, in urban settings, coastal regions, brackish water, and swamps serve as breeding grounds for malaria vectors [49]. In Papua Province, 75% of children under 5 reside in rural areas. Our study found that living in rural areas was a risk factor for malaria infection among children under 5, although the association was not statistically significant. This may suggest that urban areas also have vector breeding sites [13]. In contrast, research conducted in Malawi indicated that a composite measure of urbanicity was inversely associated with the risk of malaria [50]. Furthermore, the distinction between urban and rural areas is influenced by various social and environmental characteristics [51].

Research from African countries has demonstrated associations between poverty, household wealth index, and malaria prevalence among under-5 children [24,29,52]. In this study, the number of family members served as a predictor of socioeconomic status. Based on prior research, a larger family size may tend to indicate poorer socioeconomic conditions of a household [53]. Although a higher number of family members was associated with an increased risk of malaria infection among children under 5, this association was not statistically significant. This may suggest that the socioeconomic conditions in Papua Province were relatively uniform among the families studied. Previous research has indicated that boys are at higher risk of malaria than girls [27,52]. However, our study found no association between sex and malaria infection in children under 5. This absence of difference could be attributed to the similar risk of exposure for boys and girls, as both typically remain indoors at night when malaria vectors are most active.

The use of insecticide-impregnated nets is influenced by antenatal care visits, which promote their use among children under 5 [54]. In this study, we assumed that parents were more likely to ensure that their own children slept under nets recently impregnated with insecticide compared to other children in this age group. However, the children of other individuals were not found to be at a significantly higher risk of malaria infection. It is possible that parents are similarly likely to apply similar protective measures, such as using insecticide-impregnated nets within the last 3 years, regardless of the child’s status.

Significant associations linked factors such as sleeping under nets treated with insecticide recently (no more than 3 years ago) and healthy housing conditions with the incidence of malaria infection among children under 5. However, other factors, including the area of residence, socioeconomic status, and the presence of ventilation screens, displayed no significant associations in the multivariate analysis. Since not sleeping under an insecticide-treated net impregnated within the past 3 years was protective against malaria infection—a notable finding—it is possible that these nets are being used inconsistently, and efforts should be made to promote their regular use. Given that just over half of the children under 5 are sleeping under insecticide-impregnated nets treated within the past 3 years, health education initiatives should be intensified to encourage the consistent use of effective nets among this vulnerable population [55]. Furthermore, the development of additional healthy housing interventions, such as ensuring that living room windows are opened daily to prevent mosquitoes from finding refuge, should be considered [31,43].

Limitations of the study

When respondents are asked about malaria diagnoses over the past year, recall bias is possible. However, since malaria is diagnosed through blood examination and the parents or other family members of children under 5 typically have a clear recollection of the illness, the likelihood of recall bias for malaria infection was relatively low for the present study. Furthermore, the questionnaires were administered to individuals who were closely familiar with the children’s health status, thus minimizing the risk of confirmation bias.

The practices of sleeping under an insecticide-impregnated net within the past 3 years old, as well as the use of ventilation screens, were assessed with simple yes-or-no responses. Further research is required to clarify the protective value according to the regularity of insecticide net usage and the condition of the ventilation screen.

Conclusion

This study highlights the complexity of factors contributing to malaria infection in Papua Province, Indonesia, with a focus on children under 5 years old. Factors such as sociodemographic conditions, awareness of malaria prevention, and the use of insecticide-impregnated nets are critical. Additionally, housing conditions, including windows, ventilation, and light exposure, influence the risk of contact between humans and malaria vectors. These findings indicate that a holistic approach, which encompasses all of these elements, is necessary to address malaria infection in Indonesia. Consequently, a more nuanced understanding of the factors driving malaria transmission could inform the development of more effective interventions. These could include the use of insecticide-impregnated nets, public education campaigns on malaria prevention, and improvements in housing conditions to minimize the risk of contact with malaria vectors.

HIGHLIGHTS

• Reducing malaria infection is crucial, particularly among high-risk groups. This study aimed to identify factors associated with malaria infection in children under 5 years old.

• Socioeconomic determinants, preventive behaviors, and household conditions influence malaria infection rates among under-5 children.

• The study demonstrates that sleeping under an insecticide–impregnated net that was treated within the last 3 years was associated with malaria infection, a notable result potentially related to inconsistent use. Additionally, opening living room windows daily contributes to malaria prevention by improving air circulation, discouraging mosquitoes from seeking refuge indoors. Maintaining a healthy household environment is helpful in preventing malaria transmission.