Acute respiratory infections (ARIs) remain a leading cause of morbidity and mortality in children, particularly in low- and middle-income countries (LMICs) [1]. Despite progress in reducing infant mortality, they continue to account for a significant proportion of preventable consultations, hospitalizations, and deaths [2].

Sub-Saharan Africa bears a large part of this burden, driven by structural factors such as poverty, inadequate housing, and limited access to clean energy sources [3]. The use of biomass fuels exposes many children daily to harmful particles and toxic gases, constituting a major respiratory risk factor [4]. This is compounded by socioeconomic constraints, including low household income, low parental education levels, and limited access to healthcare, which contribute to delays in seeking treatment, limit preventive practices, and worsen disease progression [5]. Overcrowded households also contribute to the transmission of respiratory pathogens [6].

Nutritional status also influences vulnerability to infections. Malnutrition and micronutrient deficiencies impair immune defenses and increase the risk of severe respiratory infections [7]. While most research focuses on children under five, school-aged children remain exposed to similar risks related to communal living and environmental exposures [8]. However, data on this population remain limited in the Democratic Republic of Congo.

Ecosocial and syndemic approaches emphasize that the risk of acute respiratory infections (ARIs) results from the interaction of biological, environmental, and socioeconomic determinants rather than from a single factor [9]. In the DRC, rapid urbanization, the continued use of biomass, and high population density maintain conditions conducive to the transmission of respiratory diseases [10].

In this context, this study aimed to assess the independent and combined effects of sociodemographic, environmental, and nutritional determinants of ARIs in the Kamina Health Zone, in order to better understand risk factors and guide integrated public health interventions.

Table 1. Sociodemographic characteristics and nutritional profile of the children studied (N = 384).

A total of 384 children aged 0 to 14 years were included in the study. Boys were slightly in the majority (53.1%), and the mean age was 8.2 ± 3.9 years, with a predominance of children aged 5 to 9 years (40.6%). The majority of households belonged to a low socioeconomic group (64.6%). Nutritionally, most children had a normal BMI (81.5%), while the coexistence of malnutrition (2.6%) and overweight (15.9%) indicates a double nutritional burden. Furthermore, more than three-quarters of households used unsafe water for food preparation (77.3%). Finally, approximately half of the children were exclusively breastfed (51.3%) (see Table 1).

Bivariate analysis revealed a statistically significant association between several anthropometric characteristics and the occurrence of acute respiratory infections (ARIs). Children under 5 years of age had a higher risk of ARI than those aged 5 years or older (PR = 2.41; 95% CI: 1.12 - 5.18; p = 0.024). The BMI is not significantly associated with an increased PR of ARI (see Table 2).

Table 2. Relationship between anthropometric parameters and the occurrence of acute respiratory infections.

Note: PR = Prevalence ration; CI = confidence interval.

Table 3. Domestic environmental pollution factors associated with acute respiratory infections (ARIs) in children surveyed in the Kamina community.

Table 3 shows that certain household exposures were significantly associated with the occurrence of acute respiratory infections (ARIs) in children. Exposure to household chemicals nearly tripled the PR of ARIs compared to unexposed children (PR = 2.91; 95% CI: 1.26 - 6.71; p = 0.009). Similarly, carrying the child during cooking (PR = 2.70; 95% CI: 1.29 - 5.65; p = 0.006) and during fire lighting (PR = 2.25; 95% CI: 1.18 - 4.29; p = 0.012) were associated with a significantly increased risk of ARIs, reflecting the harmful effect of close exposure to combustion smoke.

Furthermore, the use of an open fireplace tended to increase the odds of ARI (PR = 1.69; 95% CI: 0.90 - 3.17), although this did not reach statistical significance (p = 0.100). Conversely, no association was observed between passive smoking and ARI after data verification (PR = 1.03; p = 0.957).

Table 4. Independent determinants of acute respiratory infections: results of multivariate logistic regression.

Multivariate logistic regression analysis shows that ARIs in children in the Kamina Health Zone result from the interaction of socioeconomic, environmental, and behavioral factors. Children from low socioeconomic status households had a higher risk of ARIs (aOR = 2.81; 95% CI: 1.45 - 5.42), as did those living in overcrowded households (aOR = 1.88; 95% CI: 1.05 - 3.36). Domestic exposures were also important determinants, including indoor smoke (aOR = 2.42; 95% CI: 1.31 - 4.50), the use of household chemicals (aPR = 2.65; 95% CI: 1.15 - 6.10), carrying the child while cooking (aPR = 2.48; 95% CI: 1.18 - 5.21), or while lighting a fire (aPR = 2.12; 95% CI: 1.05 - 4.28). Lack of access to healthcare appeared to be the factor most strongly associated with ARIs (aOR = 3.57; 95% CI: 1.78 - 7.14), while the consumption of street food also increased the odds of developing these infections (aOR = 3.12; 95% CI: 1.60 - 6.08) (see Table 4).

The study population lived in a socioeconomic and environmental context conducive to the occurrence of acute respiratory infections (ARIs) [11]. The slight male predominance observed is consistent with available data, as sex is not generally considered an independent risk factor [12]. While the high proportion of school-aged children may reflect greater exposure to contact in group settings, the vulnerability of younger children remains linked to immune immaturity [13]. In the Kamina Health Zone, precarious living conditions, overcrowding, domestic smoke, and limited access to healthcare illustrate the significant role of structural and environmental factors in maintaining the burden of ARIs in children, as also highlighted by the WHO [14], UNICEF [15], and the Global Burden of Disease study [16].

The majority of children had a normal BMI (81.5%), but the coexistence of malnutrition (2.6%) and overweight (15.9%) reflects a nutritional transition [17]. The literature shows that malnutrition impairs immune mechanisms and increases susceptibility to respiratory infections, while adequate nutrition strengthens protection against these diseases [7][18]. However, despite this recognized link, our study did not find a statistically significant association between malnutrition and ARIs. This lack of association could be explained by the small proportion of malnourished children included in the study, thus limiting the statistical power needed to detect a significant effect (Table 2 and Table 3).

Regarding dietary practices, only the consumption of street food was associated with ARIs. The direct exposure to pathogenic agents (bacteria, viruses, toxins) linked to microbiological contamination and lack of hygiene during preparation/sale [19]. This direct exposure entails indirect effects via a nutritional disturbance (ultra-processed, micronutrient-poor foods) entraining a weakening of mucosal barriers and respiratory immunity [20]. This result is consistent with studies highlighting the importance of food hygiene in preventing infections [21], as well as with African studies documenting high levels of microbiological contamination of street food [22]. More recent studies confirm this reality in urban African settings [23]. Street food consumption (aOR = 3.12) was one of the strongest associations observed after the absence of healthcare access. However, our study suggests an indirect effect, mediated by increased nutritional and immune vulnerability, rather than a direct infectious effect. Conversely, no significant association was found with the use of potable water, meal frequency, or exclusive breastfeeding, consistent with the observations of other authors [24]. Although exclusive breastfeeding is widely recognized as a protective factor, this effect was not observed in our setting, likely due to the influence of other environmental and socioeconomic factors.

Our observations also suggest that childhood respiratory infections (ARIs) occur in a home environment characterized by multiple harmful exposures. Indoor air pollution, particularly from household smoke and fuels used in homes, remains a major concern [4][25]. Although secondhand smoke is recognized as a significant risk factor [26], no significant association was found in our study. This lack of association could reflect specific exposure patterns in the Kamina Health Zone or certain measurement limitations, but it is consistent with the observations of previous researchers [27].

Furthermore, exposure to household chemicals appears consistent with data from the literature [28]. Disinfectants and volatile organic compounds (VOCs) present in the home environment are likely to contribute to pediatric respiratory morbidity, suggesting that an accumulation of irritants in homes promotes the occurrence of ARIs [29]. Similarly, holding a child while cooking or lighting a fire increases their direct exposure to biomass fumes, a phenomenon already described in similar contexts [30]. Recent literature highlights that these repeated early exposures can not only promote acute infections but also induce chronic bronchial inflammation that can permanently impair respiratory function [31].

Delayed or insufficient access to healthcare [5][32] and household overcrowding [6] also illustrate the significant role of living conditions in the development of acute respiratory infections (ARIs). Lack of early access to care appears to be a major determinant, consistent with previous observations [33]. Overcrowding (aOR = 1.88; 95% CI: 1.05 - 3.36) showed a significant but more moderate association. This result is consistent with the literature, which describes overcrowding less as a direct causal factor than as an amplifier of infectious agent transmission [6]. In our study, its relatively moderate effect compared to toxic exposures suggests that person-to-person transmission may play a secondary role in an already heavily polluted environment.

In this context, ARIs appear less as the consequence of an isolated factor than as a reflection of cumulative vulnerability, where domestic exposures, daily behaviors, socioeconomic conditions, and constraints in accessing healthcare intersect [9]. These results underscore the need for integrated interventions combining improvements to the home environment, the promotion of protective behaviors, and enhanced early access to healthcare services to sustainably reduce the burden of ARIs in children.

Acute respiratory infections are defined as the presence of fever, cough as well as rapid breathing.

Acute respiratory infections in children in the Kamina Health Zone appear to be the expression of a multifactorial vulnerability, shaped by the interaction between living conditions, environmental exposures, and constraints in accessing healthcare. The absence or delay in seeking healthcare services is the main factor associated with ARIs. The consumption of street food, domestic exposures related to cooking fumes, carrying children while lighting fires, and the use of household chemicals, as well as household overcrowding, also contribute to maintaining this burden on children.

The interpretation of these results must take into account the cross-sectional nature of the survey, the reliance on self-reported data, and the lack of objective measurements of environmental exposures. Longitudinal studies incorporating a more precise assessment of these exposures would allow for a deeper understanding of the mechanisms involved.

The sustainable reduction of childhood acute respiratory infections (ARIs) in Kamina requires an integrated and multisectoral approach, combining improved early access to care, reduced harmful domestic exposures, the promotion of protective practices, and improved living conditions for households.