Severe Dengue and Associated Hemophagocytic Lymphohistiocytosis in PICU

Dengue-Associated Hemophagocytic Lymphohistiocytosis: A Narrative Review of Its Identification and Treatment

Dengue's lack of specific treatments beyond supportive care prompts a focus on uncovering additional pathophysiological factors. Dengue-associated hemophagocytic lymphohistiocytosis (HLH), characterized by dysregulated macrophage activation and cytokine storm, remains underexplored despite its potential to worsen disease severity and mortality. While rare, dengue-associated HLH disproportionately affects severe cases, significantly impacting mortality rates. To mitigate high mortality, early identification and familiarity with dengue-associated HLH are imperative for prompt treatment by clinicians. This narrative review therefore aims to examine the current clinical and therapeutic knowledge on dengue-associated HLH, and act as a resource for clinicians to improve their management of HLH associated with severe dengue. Dengue-associated HLH should be considered for all cases of severe dengue and may be suspected based on the presence of prolonged or recurrent fever for >7 days, or anemia without intravascular hemolysis or massive bleeding. Diagnosis relies on fulfilling at least five of the eight HLH-2004 criteria. Treatment predominantly involves short courses (3-4 days) of high-dose steroids (e.g., dexamethasone 10 mg/m2), with additional therapies considered in more severe presentations. Notably, outcomes can be favorable with steroid therapy alone.

Hyperferritinemia in Severe Dengue Infection: Single-Center Retrospective Cohort Study

OBJECTIVES

Hyperferritinemia in the critical phase of dengue infections may correlate with severe dengue ( sd ) disease, and our primary objective was to examine the association between ferritin level on day 1 of PICU admission and 2009 World Health Organization (WHO) criteria for sd . Our secondary objective was outcome in relation to care. It is unclear whether immunomodulatory therapy during the critical phase may restore immune homeostasis and mitigate disease severity.

DESIGN, SETTING, AND PATIENTS

Retrospective cohort study of children with dengue 1 month to 16 years old with admission ferritin greater than or equal to 500 ng/mL requiring PICU admission. Demographics, clinical, and laboratory parameters, presence of the 2009 WHO sd criteria and outcomes were analyzed. Immunomodulatory therapy was used when there was persistent hyperinflammation beyond the critical phase of plasma leakage.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Fifty-five patients were admitted in the critical phase of dengue with median (interquartile range) ferritin levels of 8,105 ng/mL (2,350-15,765 ng/mL). Patients with at least one WHO sd category had higher ferritin levels compared to those without any sd criteria, with the highest levels in eight patients with all three sd categories. In our cohort of 55, 52 patients (94%) recovered with standard supportive therapy. Recovery was associated with decreased ferritin levels that occurred in parallel with improved circulation and platelet counts; this included 22 of 24 patients with admission ferritin levels greater than or equal to 10,000 ng/mL and two with ferritin greater than 1,00,000 ng/mL. Immunomodulation was used in three patients with unremitting fever, persistent hyperferritinemia, and progressive multiple organ dysfunction beyond the critical phase, of whom two died.

CONCLUSIONS

Hyperferritinemia in the critical phase of sd is associated with the number of 2009 WHO sd criteria present. Our data also indicate that many patients with sd recover well with supportive care.

Clinical and Laboratory Characteristics of Hemophagocytic Lymphohistiocytosis in Children With Severe Dengue During the 2019-2020 Outbreak in Southern Colombia

BACKGROUND

Hemophagocytic lymphohistiocytosis (HLH) is characterized by uncontrolled activation of inflammatory cells and an exaggerated release of cytokines. It can be triggered by different factors, including viruses, such as dengue. The objective of this study was to characterize the clinical and laboratory profiles of children with severe dengue and HLH, and to identify the risk factors for this clinical complication.

METHODS

An analytical study was conducted in children with severe dengue who were treated in an intensive care unit between January 2019 and March 2020. Clinical and laboratory factors were compared between patients with and without HLH.

RESULTS

HLH represented 13.4% (15/112) of children with severe dengue. Patients with HLH had a long-lasting fever (10.1 vs. 5.8 days; P = 0.012), low hemoglobin levels (7.6 vs. 10.8 g/dL; P = 0.000) and high aspartate aminotransferase values (4443 vs. 1061 U/L; P = 0.002), alanine transaminase (1433 vs. 487 U/L; P = 0.004), partial thromboplastin time (80.6 vs. 51.8 seconds; P = 0.010), prothrombin time (23.5 vs. 19.6 seconds; P = 0.024), triglycerides (333.7 vs. 223.2 mg/dL; P = 0.005), lactate dehydrogenase (4209 vs. 1947 U/L; P = 0.006), soluble CD25 (3488 vs. 1026 pg/mL; P = 0.014), and presented with higher frequency of myocarditis (66.7% vs. 38.3%; P = 0.048), hepatitis (5.3% vs. 1.3%; P = 0.014), bacterial coinfection (73.3% vs. 26.7%; P = 0.010) and fatal outcome (26% vs. 5%; P = 0.037).

CONCLUSIONS

HLH is a serious life-threatening clinical complication of dengue virus infection that must be considered, particularly during outbreaks.

Diagnostic, Management, and Research Considerations for Pediatric Acute Respiratory Distress Syndrome in Resource-Limited Settings: From the Second Pediatric Acute Lung Injury Consensus Conference

OBJECTIVES

Diagnosis of pediatric acute respiratory distress syndrome (PARDS) in resource-limited settings (RLS) is challenging and remains poorly described. We conducted a review of the literature to optimize recognition of PARDS in RLS and to provide recommendations/statements for clinical practice and future research in these settings as part of the Second Pediatric Acute Lung Injury Consensus Conference (PALICC-2).

DATA SOURCES

MEDLINE (Ovid), Embase (Elsevier), and CINAHL Complete (EBSCOhost).

STUDY SELECTION

We included studies related to precipitating factors for PARDS, mechanical ventilation (MV), pulmonary and nonpulmonary ancillary treatments, and long-term outcomes in children who survive PARDS in RLS.

DATA EXTRACTION

Title/abstract review, full-text review, and data extraction using a standardized data collection form.

DATA SYNTHESIS

The Grading of Recommendations Assessment, Development, and Evaluation approach was used to identify and summarize evidence and develop recommendations. Seventy-seven studies were identified for full-text extraction. We were unable to identify any literature on which to base recommendations. We gained consensus on six clinical statements (good practice, definition, and policy) and five research statements. Clinicians should be aware of diseases and comorbidities, uncommon in most high-income settings, that predispose to the development of PARDS in RLS. Because of difficulties in recognizing PARDS and to avoid underdiagnosis, the PALICC-2 possible PARDS definition allows exclusion of imaging criteria when all other criteria are met, including noninvasive metrics of hypoxemia. The availability of MV support, regular MV training and education, as well as accessibility and costs of pulmonary and nonpulmonary ancillary therapies are other concerns related to management of PARDS in RLS. Data on long-term outcomes and feasibility of follow-up in PARDS survivors from RLS are also lacking.

CONCLUSIONS

To date, PARDS remains poorly described in RLS. Clinicians working in these settings should be aware of common precipitating factors for PARDS in their patients. Future studies utilizing the PALICC-2 definitions are urgently needed to describe the epidemiology, management, and outcomes of PARDS in RLS.

Pathobiology, Severity, and Risk Stratification of Pediatric Acute Respiratory Distress Syndrome: From the Second Pediatric Acute Lung Injury Consensus Conference

OBJECTIVES

To review the literature for studies published in children on the pathobiology, severity, and risk stratification of pediatric acute respiratory distress syndrome (PARDS) with the intent of guiding current medical practice and identifying important areas for future research related to severity and risk stratification.

DATA SOURCES

Electronic searches of PubMed and Embase were conducted from 2013 to March 2022 by using a combination of medical subject heading terms and text words to capture the pathobiology, severity, and comorbidities of PARDS.

STUDY SELECTION

We included studies of critically ill patients with PARDS that related to the severity and risk stratification of PARDS using characteristics other than the oxygenation defect. Studies using animal models, adult only, and studies with 10 or fewer children were excluded from our review.

DATA EXTRACTION

Title/abstract review, full-text review, and data extraction using a standardized data collection form.

DATA SYNTHESIS

The Grading of Recommendations Assessment, Development, and Evaluation approach was used to identify and summarize relevant evidence and develop recommendations for clinical practice. There were 192 studies identified for full-text extraction to address the relevant Patient/Intervention/Comparator/Outcome questions. One clinical recommendation was generated related to the use of dead space fraction for risk stratification. In addition, six research statements were generated about the impact of age on acute respiratory distress syndrome pathobiology and outcomes, addressing PARDS heterogeneity using biomarkers to identify subphenotypes and endotypes, and use of standardized ventilator, physiologic, and nonpulmonary organ failure measurements for future research.

CONCLUSIONS

Based on an extensive literature review, we propose clinical management and research recommendations related to characterization and risk stratification of PARDS severity.

Dengue and Plasmodium falciparum Coinfection With Secondary Hemophagocytic Lymphohistiocytosis in a 3-Year-old Boy: A Clinical Conundrum

Hemophagocytic lymphohistiocytosis (HLH) is a multisystem disease wherein there is an exaggerated immune system activation following a trigger such as infection, malignancy, or autoimmune diseases. Here we report a case of a 3-year-old boy who presented to us with fever, was diagnosed with dengue fever, and treatment started for the same. Clinical response was poor to treatment and high-grade fever persisted. Subsequent evaluation showed Plasmodium falciparum malaria and treatment was initiated with antimalarial drugs. Further clinical deterioration with poor trend of laboratory values over the next few days prompted evaluation for HLH; workup was positive satisfying the HLH-2004 criteria and IV dexamethasone was started. The child gradually improved and was discharged with normal counts on follow-up over the next 3 months. This article emphasizes on the importance of high degree of suspicion, early workup, and initiation of treatment for HLH for a better outcome.

Neonatal Dengue With HLH: Perks of Early Diagnosis and Management

BACKGROUND

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening, aggressive syndrome. It can be primary, which involves genetic mutation with an early presentation, or secondary to infections, malignancies, etc., due to absence of immune downregulation. It is a very rare condition in newborns. Dengue is a potential virus causing HLH, but, in newborns, there are only few case reports and limited clinical literature.

OBSERVATION

Herein, in this report, we highlight a case of neonatal HLH, triggered by perinatal dengue. The neonate manifested clinically within the first week of life, the earliest reported timeline so far in the literature.

CONCLUSION

HLH should be excluded in neonates especially when multisystem involvement cannot be explained by sepsis alone.

Comparative analysis of liver involvement caused by two DENV-2 lineages using an immunocompetent murine model

Dengue (DEN) is the most prevalent arbovirus among humans, and four billion people live at risk of infection. The clinical manifestations of DEN are variable, and the disease may present subclinically or asymptomatically. A quarter of patients develop classical dengue (CD) or severe dengue (SD), which is potentially lethal and involves vascular permeability changes, severe hemorrhage and organ damage. The involvement of the liver is a fairly common feature in DEN, and alterations range from asymptomatic elevation of transaminases to acute liver failure. Since its introduction in Brazil in 1990, two strains of Dengue virus (DENV) serotype 2 (DENV-2) have been detected: Lineage I, which is responsible for an outbreak in 1991, and Lineage II, which caused an epidemic greater than the previous one and had a different epidemiological profile. To date, studies on different strains of the same serotype/genotype and their association with disease severity are scarce. In addition, one of the greatest challenges regarding the study of DEN pathogenesis and the development of drug and vaccine therapies is the absence of an animal model that reproduces the disease as it occurs in humans. The main goals of this study were to assess BALB/c mouse susceptibility experimentally infected by two distinct DENV-2 strains and characterize possible differences in the clinical signs and alterations induced in the liver resulting from those infections. Mice infected by the two DENV-2 lineages gained less weight than uninfected mice; however, their livers were slightly heavier. Increased AST and AST levels were observed in infected mice, and the number of platelets increased in the first 72 h of infection and subsequently decreased. Mice infected with both lineages presented leukocytosis but at different times of infection. The histopathological changes induced by both lineages were similar and comparable to the changes observed in DEN fatal cases. The viral genome was detected in two liver samples. The results demonstrate the susceptibility of BALB/c mice to both DENV-2 lineages and suggest that the changes induced by those strains are similar, although for some parameters, they are manifested at different times of infection.

Hemophagocytic Lymphohistiocytosis in a PICU of a Developing Economy: Clinical Profile, Intensive Care Needs, Outcome, and Predictors of Mortality

OBJECTIVES

To describe the clinical profile, intensive care needs, outcome, and predictors of mortality in critically ill children with hemophagocytic lymphohistiocytosis.

DESIGN

Retrospective case series.

SETTING

PICU of a tertiary care teaching hospital in North India.

PATIENTS

Children 2 months to 12 years old with the diagnosis of hemophagocytic lymphohistiocytosis admitted to PICU from January 2012 to April 2019 (7¼ yr).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Sixty-two children with hemophagocytic lymphohistiocytosis (60 secondary and two primary) were enrolled. The median (interquartile range) age of the study group was 82 months (50.5-124 mo). The median (interquartile range) Pediatric Risk of Mortality III score was 16 (10-23). Majority of hemophagocytic lymphohistiocytosis was infection-associated (n = 51; 82.3%). Among these, scrub typhus accounted for 29% of cases (n = 18), dengue 17.7% (n = 11), bacterial sepsis 14.5% (n = 9), enteric fever 6.5% (n = 4), and other infections 14.5% (n = 9). Systemic-onset juvenile idiopathic arthritis accounted for 9.7% of cases (n = 6) and malignancy for 4.8% patients (n = 3). Majority of cases were treated with steroids (77.4%) and IV immunoglobulin (25.8%). Various complications noted were shock (71%), acute kidney injury (66.1%), acute respiratory distress syndrome (41.9%), disseminated intravascular coagulation (54.8%), CNS dysfunction (54.8%), multiple organ dysfunction syndrome (82.3%), and healthcare-associated infections (14.5%). Intensive care needs for primary illness and/or hemophagocytic lymphohistiocytosis included mechanical ventilation (74.2%); packed RBC (72.3%), fresh frozen plasma (40.3%), and platelet (48.4%) transfusion; vasoactive drugs (71%); and renal replacement therapy (24.2%). The median duration of PICU stay was 5 days (2.5-9.5 d) and mortality was 59.7% (n = 37). On univariate analysis, nonsurvivors had higher Pediatric Risk of Mortality III score; higher proportion of shock, acute kidney injury, acute respiratory distress syndrome, disseminated intravascular coagulation, and multiple organ dysfunction syndrome; the need for blood and blood components, mechanical ventilation, vasoactive drugs, and renal replacement therapy; higher Vasoactive-Inotropic Score; and prolonged duration of mechanical ventilation compared with survivors.

CONCLUSIONS

Hemophagocytic lymphohistiocytosis in PICU is commonly secondary to tropical infections and associated with high mortality. Higher severity of illness; shock and multiple organ dysfunction syndrome; need for blood and blood products, mechanical ventilation, vasoactive drugs, and renal replacement therapy; higher Vasoactive-Inotropic Score; and prolonged mechanical ventilation predicted death. Treatment of underlying infection and a less intense immunosuppressive therapy (steroids ± IV immunoglobulin) are suggested options. A high index of suspicion for complicating hemophagocytic lymphohistiocytosis is required in children with prolonged fever, cytopenias, organomegaly, and organ dysfunction not responding to conventional treatment.

Soluble Interleukin-2 Receptor Level as a Marker of Hemophagocytic Lymphohistiocytosis in Children With Severe Dengue

Dengue induced-hemophagocytic lymphohistiocytosis (HLH) is increasingly recognized as an important cause of secondary HLH. Early identification of dengue HLH and directed therapy for HLH may help to alter the outcomes in critically ill patients. Soluble interleukin-2 receptor (IL2R) is a useful inflammatory marker and is seen to correlate with HLH disease activity. There is scarcity of data on IL2R in pediatric dengue patients with HLH. All patients (age < 18 years) with severe dengue confirmed by positive dengue IgM ELISA admitted to PICU were retrospectively enrolled. Patientswere screened for presence of HLH according to HLH 2004 criteria. Hemogram, ferritin, fibrinogen, liver, and renal function tests were noted. Patients who met four or more HLH criteria were treated with steroids and IL2R levels were sent to confirm the diagnosis of HLH. Out of 15 patients, nine patients met the criteria of HLH. IL2R levels were high in all HLH patients (mean 51,711, range 18,000-98,715 pg/mL). Mean ferritin levels were high in the HLH group as compared to non-HLH group (mean ferritin 34,593 vs. 3,206 ng/mL; p-value 0.004). Liver dysfunction was notably higher in the HLH group compared to non-HLH group (mean alanine aminotransferase 6,621 U/L vs. 165.6 U/L; p-value 0.04, mean aspartate aminotransferase 2,145 U/L vs. 104.2 U/L; 0.04, bilirubin level 4.2 mg/dL vs. 0.7 mg/dL; p-value 0.03). Four patients in the HLH group had acute kidney injury (AKI) and two required renal replacement therapy in the form of sustained low efficiency dialysis (SLED). Requirement for invasive ventilation was exclusively seen in HLH group and three patients developed ARDS. Two patients each in HLH and non-HLH group had shock requiring vasoactive therapy in addition to fluids. Mean days of ICU and hospital stay were higher in HLH group vs. non-HLH group but not statistically significant (6.4 vs. 4.4; p-value 0.32 and 8.44 vs. 5.6; p-value 0.18 days, respectively). All children in HLH group received steroids as per HLH protocol. In the HLH group, seven survived while two died. In the non-HLH group, all five patients survived. We concluded that IL2R levels are high in dengue HLH and useful for definitive diagnosis. Early recognition of this condition in severe dengue and prompt steroid therapy improves chances of better outcome.