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Association between serum vitamin-D levels and severity of dengue fever in children: A cross-sectional study
*Corresponding author: Raziya Banu J, Department of Pediatrics, Al-Ameen Medical College and Hospital, Vijayapura, Karnataka, India. banumj8@gmail.com
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Received: ,
Accepted: ,
How to cite this article: Banu JR, Talikoti AB, Thobbi A, Zoheb M. Association between serum vitamin-D levels and severity of dengue fever in children: A cross-sectional study. Karnataka Paediatr J. doi: 10.25259/KPJ_55_2025
Abstract
Objectives:
Dengue fever is a prevalent viral disease transmitted by mosquitoes, with clinical presentations varying from mild fever to serious, life-threatening conditions. Although Vit D is recognised for its vital role in immune system regulation, its influence on the severity of dengue infection in paediatric patients remains inadequately understood. This study aims to measure serum Vitamin-D levels in children aged between 1 and 15 years diagnosed with dengue fever and to examine the association between Vitamin-D status and the severity of the illness.
Material and Methods:
A hospital-based cross-sectional study was conducted involving 100 children confirmed to have dengue infection through laboratory tests. The severity of the disease was classified according to the 2009 World Health Organization guidelines into three categories: Dengue without warning signs, dengue with warning signs and severe dengue. Serum concentrations of 25-hydroxyVit-D were determined utilising a chemiluminescent immunoassay technique.
Results:
There was a significant decline in mean serum Vit-D levels as the severity of dengue increased, with levels averaging 28.5 ± 6.8 ng/mL in mild cases compared to 15.8 ± 4.9 ng/mL in severe cases (p = 0.001). Vit-D deficiency, defined as levels below 20 ng/mL, was found in 80% of severe dengue cases versus 10% of mild cases (p = 0.001). Furthermore, serum Vit-D had a positive correlation with platelet counts (r = 0.643, p = 0.001) and a negative correlation with haematocrit levels (r = −0.543, p = 0.002).
Conclusion:
Vitamin-D deficiency was significantly associated with increased severity of dengue fever in children. Regular assessment and correction of Vitamin-D levels may help in forecasting disease progression and could be integrated as part of the therapeutic strategy in managing dengue illness.
Keywords
Adolescent
Dengue
Disease Severity
Immunoassay
Vitamin D Deficiency
INTRODUCTION
Dengue fever is an infectious viral disease that rapidly spreads and is transmitted mainly by the Aedes aegypti mosquito. It poses a major public health challenge in tropical and subtropical regions, with countries like India experiencing frequent outbreaks.[1] The clinical symptoms of dengue vary significantly, ranging from no symptoms or mild fever to severe conditions such as dengue haemorrhagic fever (DHF) and dengue shock syndrome (DSS), both of which contribute to high rates of illness and death, particularly in children.[2] The World Health Organization (WHO) categorises dengue severity based on warning signs and clinical complications, emphasising the need to identify individuals at risk of severe progression promptly.
Vit-D, a fat-soluble secosteroid hormone, plays a vital role in maintaining calcium homeostasis and bone health, while also regulating the immune system. It exerts influence on both innate and adaptive immunity by modulating the activity of immune cells such as macrophages, dendritic cells, T cells and B cells.[3] These immune-regulating effects of Vit-D contribute to the body’s defence mechanisms against a variety of infections, including respiratory illnesses, tuberculosis and viral diseases. Recent research indicates that insufficient Vit-D levels may increase susceptibility to infections and worsen clinical outcomes.[4]
The immunopathogenesis of dengue is characterised by a complex interplay between viral components and the host’s immune system, often resulting in excessive inflammatory responses and increased vascular permeability in severe cases.[5] It has been suggested that adequate Vit-D levels may help regulate this immune activity and potentially lower the risk of developing severe dengue. Conversely, a deficiency in Vit-D might cause abnormal immune responses, leading to increased disease severity.[6]
Although dengue represents a significant global health challenge and the immunomodulatory role of Vit-D is well established, data linking serum Vit-D concentrations to dengue severity in children remain scarce.[7] Paediatric populations are particularly vulnerable to severe forms of dengue due to their underdeveloped immune systems. Investigating the association between Vit-D deficiency and disease severity could provide valuable information for risk stratification and the design of supplementary therapeutic interventions.
Therefore, this study aims to evaluate serum Vit-D levels in children aged 1–15 years diagnosed with dengue fever and to explore the connection between Vit-D status and clinical severity. The findings could contribute to enhancing clinical management and preventive strategies in regions where dengue is endemic.
MATERIAL AND METHODS
Study design and setting
This research was a hospital-based, observational cross-sectional study carried out in the Pediatric Department of Al Ameen Medical College over a 1-year period from March 2024 to March 2025.
Study population
The study enrolled children aged 1–15 years who presented with clinical signs suggestive of dengue fever and whose diagnosis was confirmed through laboratory testing.
Inclusion criteria
Children between the ages of 1 and 15 years
Laboratory confirmation of dengue fever through a positive NS1 antigen test or dengue immunoglobulin M (IgM) enzyme-linked immunosorbent assay (ELISA)
Presentation within 5 days from the onset of symptoms.
Exclusion criteria
Children with chronic medical conditions such as chronic liver disease, kidney disease, or immunodeficiency disorders
Those receiving Vit-D supplements or treatment
Children suffering from co-infections or malnutrition that could affect Vit-D metabolism
Cases where guardians did not provide consent.
Sample size calculation
The sample size was estimated based on comparing means among groups categorised by disease severity, assuming a medium effect size. With a confidence interval of 95%, statistical power of 80% and effect size (Cohen’s d) of 0.5, approximately 64 participants per group were required. Considering three groups – dengue without warning signs, dengue with warning signs and severe dengue – and accounting for potential dropouts, a total of 100 children were deemed sufficient to detect significant differences statistically.
Data collection
Following written informed consent from parents or legal guardians, demographic information, clinical history and physical examination findings were collected using a standardised pro forma. Dengue severity was classified per the WHO 2009 guidelines into three categories: Dengue without warning signs, dengue with warning signs and severe dengue. Laboratory confirmation was obtained by detecting NS1 antigen in early illness stages and/or dengue IgM antibody using ELISA, according to hospital protocols. Blood samples were collected at admission before any treatment began to measure serum 25-hydroxyVit-D levels. These measurements were performed in the hospital biochemistry laboratory using chemiluminescent immunoassay technology. Vit-D status was categorised as deficient (<20 ng/mL), insufficient (20–30 ng/mL) or sufficient (>30 ng/mL). Data were compiled and analysed statistically using Statistical Package for the Social Sciences version 25.
Data analysis
Continuous variables such as serum Vit-D concentrations were expressed as mean ± standard deviation or median with interquartile ranges based on data distribution. Comparisons of Vit-D levels among the three dengue severity groups were conducted using one-way analysis of variance or the Kruskal– Wallis test, depending on suitability. The association between Vit-D deficiency and severe dengue was assessed using the Chi-square test. A p< 0.05 was taken as statistically significant.
RESULTS
This study involved 100 children diagnosed with dengue infection confirmed by laboratory tests. The average age of the participants was 8.25 ± 4.20 years, with ages spanning from 1 to 15 years. Age distribution showed that 30% were aged 1–5 years, 40% between 6 and 10 years, and the remaining 30% were 11–15 years old. Males constituted 55% (n = 55) and females 45% (n = 45) of the cohort, indicating a slight male predominance.
Regarding disease severity, half of the patients (50%, n = 50) presented with dengue without warning signs, 35% (n = 35) had dengue with warning signs and 15% (n = 15) were classified as severe dengue, indicating that a minority suffered from critical illness. Details of this distribution are shown in Table 2.
| Parameter | Value |
|---|---|
| Age (years), mean±SD | 8.25±4.2 |
| Age groups in years n (%) | |
| 1–5 | 32 (32%) |
| 6–10 | 38 (38%) |
| 11–15 | 30 (30%) |
| Gender, n (%) | |
| Male | 55 (55%) |
| Female | 45 (45%) |
| Severity category | Number of children | Percentage (%) |
|---|---|---|
| Dengue without warning signs | 50 | 50 |
| Dengue with warning signs | 35 | 35 |
| Severe dengue | 15 | 15 |
A significant variation in serum Vit-D levels was observed among the three severity groups (F = 35.28, p = 0.001). The lowest mean Vit-D concentration was found in patients with severe dengue (15.8 ± 4.9 ng/mL), followed by those exhibiting warning signs (22.1 ± 5.4 ng/mL), while the highest levels were seen in patients without warning signs (28.5 ± 6.8 ng/mL). This inverse trend suggests a strong negative relationship between Vit-D levels and the severity of dengue [Table 3].
| Dengue severity | Vitamin D Level Mean±SD (ng/mL) | F value, One-way ANOVA | p value |
|---|---|---|---|
| Dengue without warning signs | 28.5±6.8 | 35.28 | 0.001* (Significant) |
| Dengue with warning signs | 22.1±5.4 | ||
| Severe dengue | 15.8±4.9 |
A statistically significant link existed between Vit-D status and clinical dengue severity (χ2 = 28.65, p = 0.001). In cases of severe dengue, Vit-D deficiency (<20 ng/mL) was present in 80% of patients, compared to 43% in those with warning signs and only 10% among patients without warning signs. Conversely, Vit-D sufficiency (>30 ng/mL) predominated in the group without warning signs (40%) and was absent in the severe dengue group. These findings emphasise the association of low Vit-D levels with increased dengue severity in children. Serum Vit-D also correlated positively with platelet counts (r = 0.643, p = 0.001) and serum alanine aminotransferase (ALT) levels (r = 0.413, p = 0.001) and negatively with haematocrit values (r = –0.543, p= 0.002). No significant correlation was found with total white blood cell counts (r = 0.124, p = 0.35). The detailed results are summarised in Table 5.
| Vitamin D Status | Dengue without warning signs (n=50) | Dengue with warning signs (n=35) | Severe dengue (n=15) | Total (n=100) | Chi Square (χ2) and p value |
|---|---|---|---|---|---|
| Deficient (<20 ng/mL) | 5 (10%) | 15 (43%) | 12 (80%) | 32 (32%) | χ2=28.65;p=0.001* (Significant) |
| Insufficient (20–30) | 25 (50%) | 15 (43%) | 3 (20%) | 43 (43%) | |
| Sufficient (>30) | 20 (40%) | 5 (14%) | 0 (0%) | 25 (25%) |
| Laboratory Parameter | Mean±SD | Pearson's Correlation (r) | p value |
|---|---|---|---|
| Platelet count (×10≥/µL) | 90,000±30,000 | 0.643 | 0.001* |
| Hematocrit (%) | 44.2±5.1 | −0.543 | 0.002* |
| White blood cell count (×10≥/µL) | 4,200±1,200 | 0.124 | 0.35NS |
| Serum ALT (U/L) | 65.76±30.12 | 0.413 | 0.001* |
NS: Non-Significant ; * indicats significant (p<0.05), Pearsons correlation analysis.
DISCUSSION
Dengue fever remains a significant public health problem globally, particularly affecting children in tropical and subtropical endemic regions.[8] The clinical manifestations range from mild fever to severe complications such as DHF and DSS. Identifying factors influencing disease severity is crucial for improving treatment and reducing morbidity and mortality. This study investigated the relationship between serum Vit-D levels and dengue severity in children aged 1–15 years, providing valuable insights into Vit-D’s immunomodulatory role in this disease.
The mean age of the children in this study was 8.25 ± 4.2 years, consistent with previous research such as that by Mishra et al.,[9] who reported a mean age of 8.7 years in paediatric dengue patients. A slight male predominance (55%) aligns with earlier epidemiological findings suggesting boys may either be at slightly higher risk or more often brought for medical care. Kumar et al.[10] also reported a similar male preponderance of 53.71%. The severity distribution showed that 50% of cases had no warning signs, 35% showed warning signs and 15% had severe dengue, mirroring typical paediatric dengue presentations. Prakash et al.[11] reported comparable findings with 52.7% of children presenting without warning signs. The most notable finding was the significant negative correlation between serum Vit-D levels and dengue severity. Children with severe dengue manifested the lowest mean Vit-D levels (15.8 ± 4.9 ng/mL), followed by those with warning signs (22.1 ± 5.4 ng/mL), and the highest values were in children without warning signs (28.5 ± 6.8 ng/mL). This graded decline implies that lower Vit-D levels may predispose to more severe illness. Similar observations were reported by Samal et al.[6] who found Vit-D levels to be lowest in severe dengue compared to less severe forms (18 ng/mL vs. 20 ng/mL vs. 21 ng/mL). Villamor et al.[12] studied paediatric patients during the febrile phase and found that lower baseline serum 25(OH)D was associated with a reduced risk of progressing to DHF/DSS. At the mechanistic level, Vit-D enhances the activity of monocyte-derived macrophages, promotes antiviral defences, downregulates pro-inflammatory cytokines, alters gene expression related to immune responses, and increases production of interleukins (IL) such as IL-10, ultimately decreasing viral loads and symptom severity.[13]
Vit-D deficiency (<20 ng/mL) was predominantly found in the severe dengue group (80%) and scarcely present in those without warning signs (10%). Meanwhile, Vit-D sufficiency (>30 ng/mL) was observed mainly in patients with mild disease and was absent in severe cases. These patterns support literature highlighting Vit-D’s role in modulating immune responses, potentially reducing excessive inflammation responsible for vascular leakage and shock in dengue. For instance, Iqtadar et al.[14] documented lower Vit-D levels in DHF grade 3 and DSS grade 4 patients compared to milder cases. Vit-D’s immunomodulatory functions encompass enhancing innate immunity through macrophage activation and synthesis of antimicrobial peptides such as cathelicidin[15] as well as regulating adaptive immunity through T-cell modulation and cytokine balance, which helps maintain immune equilibrium. Given the critical role of immune dysregulation and cytokine storms in dengue severity, adequate Vit-D levels may prevent disease progression.[16]
Correlations between Vit-D and key laboratory markers lend further support to this hypothesis. Vit-D showed a strong positive correlation with platelet number (r = 0.643, p = 0.001), suggesting a protective role in preventing platelet depletion typical in severe dengue. It also positively correlated with serum ALT (r = 0.413, p = 0.001), indicating possible interactions with liver function during infection. Conversely, a strong negative correlation with haematocrit (r = –0.543, p = 0.002) was observed, implying that Vit-D deficiency may worsen vascular leakage and haemoconcentration.
These findings underscore the potential of Vit-D status as a prognostic biomarker for dengue severity in children.[17] Early measurement upon hospital admission could aid in identifying high-risk patients needing closer monitoring and timely intervention. Vit-D supplementation could also be explored as an adjunct therapy to regulate immune response and reduce severe complications, though this requires validation through randomised clinical trials.
Limitations
While results are promising, this study has limitations. The cross-sectional design restricts the ability to establish a causal relationship between Vit-D deficiency and dengue severity. Confounding factors such as seasonal changes and nutritional status affecting Vit-D levels were not controlled. The single-centre setting and relatively small sample size may limit the generalisability of findings.
CONCLUSION
This investigation reveals a significant inverse correlation between serum Vit-D levels and dengue severity in children, with deficiency strongly associated with severe disease manifestations. Vit-D levels positively correlated with platelet counts and negatively with haematocrit values, indicating a modulatory role in dengue pathogenesis. These findings suggest Vit-D as a valuable prognostic marker and a potential target in dengue treatment. Early identification and correction of Vit-D deficiency may improve clinical outcomes in paediatric dengue patients.
Ethical approval:
The Institutional Review Board has waived ethical approval for this study.
Declaration of patient consent:
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given consent for clinical information to be reported in the journal. The patient understand that the patient’s names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Conflicts of interest:
There are no conflicts of interest.
Use of artificial intelligence (AI)-assisted technology for manuscript preparation:
The authors confirm that there was no use of artificial intelligence (AI)-assisted technology for assisting in the writing or editing of the manuscript and no images were manipulated using AI.
Financial support and sponsorship: Nil.
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