Clinical Predictors of Multiple Organ Dysfunction Syndromes in Pediatric patients with Scrub Typhus

Hyperferritinemia in children hospitalized with scrub typhus

BACKGROUND

Hyperferritinemia is increasingly associated with mortality in sepsis. Studies estimating the prevalence of hyperferritinemia in pediatric scrub typhus are limited.

METHODS

This was a secondary analysis of a prospective observational study (FERRIS) from a tertiary care teaching hospital in North India where 72 children with confirmed scrub typhus, 4 (5.5%) PCR positive, 55 (76.4%)-IgM ELISA positive, and 13 (18.1%)-both PCR and ELISA positive, were analyzed. Serum ferritin was measured in 62 children to identify the prevalence of hyperferritinemia and determine its association with mortality.

RESULTS

Hyperferritinemia (> 500 μg/L) was seen in 72.6% [n = 45] children; 26 (41.9%) were mild (500-2000 μg/L), 13 (21%) were moderate (2000-10,000 μg/L), and 6 (9.7%) were severe (> 10,000 μg/L). Early presentation to hospital (≤ 7 days of febrile illness) had more survivors than late presentation (> 7 days). Non-survivors had significantly higher PRISM III, PELOD-2, hyperlactatemia, hypoalbuminemia, organ dysfunction, need for mechanical ventilation, and need of RRT. Ferritin had poor sensitivity and specificity in predicting survival with AUC of 0.56. Organ dysfunction and risk scores as PRISM III, PELOD 2, and VIS at admission were better predictors with AUC (95% CI) of 0.72 (0.56, 0.89), 0.77 (0.63, 0.92), and 0.90 (0.78, 1.0) respectively.

CONCLUSIONS

Hyperferritinemia is common in scrub typhus but it did not predict survival. Organ dysfunction and risk scores were better predictors of mortality than ferritin.

The Prognosis Role of AST/ALT (De Ritis) Ratio in Patients with Adult Secondary Hemophagocytic Lymphohistiocytosis

PURPOSE

Secondary hemophagocytic lymphohistiocytosis (sHLH) accompanied by liver involvement, characterized by hepatomegaly and increased liver enzymes, is usually associated with elevated mortality. However, the magnitude of these associations remains unknown. Our objective was to assess the associations of the aspartate transaminase/alanine transaminase (AST/ALT, De Ritis) ratio with overall survival among adult patients with sHLH.

METHODS

A retrospective analysis was performed on 289 patients aged 18-86 years with complete serum transaminase data at diagnosis of sHLH. Multivariate Cox regression analyses and restricted cubic splines were conducted to address the association between the De Ritis ratio and the risk of mortality.

RESULTS

The median De Ritis ratio for the entire study population was 1.34 (IQR: 0.84-2.29). After a median follow-up time of 60 (range 17-227.5) days, 205 deaths occurred. After fully adjusting for hepatomegaly, albumin, fibrinogen, EBV, ferritin, etiologies, and treatment strategies, the adjusted hazard ratios (HRs) with corresponding confidence intervals (CIs) of mortality for the 2 st tertile and 3 st tertile were 1.2 (0.8-1.7) and 1.6 (1.1-2.2), respectively (P < 0.01 for trends). Restricted cubic spline confirmed a linear association between the log2-transformed De Ritis ratio and the risk of mortality. Moreover, this trend persisted in subgroups with MHLH, hyperferrinaemia, sCD25 ≤ 20,000 ng/L, patients without EBV infection, and those received treatment.

CONCLUSIONS

The De Ritis ratio is a strong and independent predictor for overall survival in patients with sHLH. As a readily available biomarker in routine clinical practice, it is used to identify patients with sHLH with inferior overall survival.

The Utility of Platelet Indices in Predicting Multiorgan Dysfunction in Scrub Typhus

Platelet indices have been used to diagnose and prognosticate infections such as tuberculosis, malaria, dengue, and septic shock. Platelet indices have previously not been used in the prediction of multiorgan dysfunction (MODS) in patients with scrub typhus. A three-year retrospective review of patient charts was performed. Patients with and without MODS were compared. Platelet indices and other clinical and laboratory variables were used in logistic regression analysis to determine significant predictors. A ROC curve was generated with the platelet indices to predict MODS. Of 189 patients, 106 were male. Respiratory rate, serum creatinine, liver function tests, platelet count, thrombocytopenia <150 × 109/L, mean platelet volume (MPV) > 7.3 fL, and plateletcrit ≤0.19% varied significantly between patients with MODS and those without. Platelet indices are inexpensive and easily available. Only thrombocytopenia along with creatinine, alanine transaminase, and abnormal chest radiograph could significantly predict MODS in patients with scrub typhus.

Dysregulated Th1 Immune and Vascular Responses in Scrub Typhus Pathogenesis

Scrub typhus is an emerging, insect-transmitted disease caused by Orientia tsutsugamushi, a Gram- and LPS-negative bacterium that replicates freely within professional phagocytes and endothelial cells. Scrub typhus is prevalent with high mortality rates, but information regarding its molecular pathogenesis, microbial virulence determinants, and key immune responses is limited. Improved animal models have recently been developed that respectively resemble the pathological features of self-limiting or severe scrub typhus in humans. Strong activation of Th1 and CD8, but not Th2 and regulatory T, immune responses, accompanied by altered angiopoietin/Tie2-related regulation, are hallmarks of lethal infection in murine models. This review, based primarily on recent advances from clinical and experimental studies, highlights tissue- and endothelial cell-specific biomarkers that are indicative of immune dysregulation. The potential roles of neutrophils and damage-associated molecular pattern molecules at late stages of disease are discussed in the context of vascular leakage, pulmonary and renal injury, and scrub typhus pathogenesis.

Scrub typhus: risks, diagnostic issues, and management challenges

Scrub typhus is an acute febrile illness in the “tsutsugamushi triangle”, transmitted by chiggers that can be treated effectively if detected early. Laboratory testing, including molecular and serological assays, is needed for confirming the diagnosis, especially in the absence of the pathognomonic eschar. In this review, factors that play a role in disease occurrence and clinical clues for diagnosis, in addition to risk factors contributing to disease severity, including mortality, are discussed in detail. Moreover, issues related to diagnostic assays, treatment, and mixed infections are also enumerated and described.