[Tsutsugamushi disease (scrub typhus) in Japan: clinical features]

Scrub Typhus-Associated Hemophagocytic Lymphohistiocytosis: Not a Rare Entity in Pediatric Age Group

BACKGROUND

Our goal was to study the demographic, clinical and laboratory profile and outcome of scrub typhus-associated hemophagocytic lymphohistiocytosis (HLH) in the pediatric age group.

METHODS

We conducted a prospective observational study in a tertiary care teaching hospital over a period of 1 year. Children in the age group of 1 month to 12 years with IgM ELISA positive for scrub typhus were included in the study. HLH was diagnosed using HLH-2004 criteria. Demographic, clinical and laboratory profile, treatment and outcome of HLH patients were noted and also compared with non-HLH scrub typhus patients.

RESULTS

Among 58 children with scrub typhus infection, 18 had HLH. The mean age of patients with HLH was 35.3 ± 44.8 months and 61% were male. Anemia, thrombocytopenia and hyperferritinemia were seen in all the patients. Hypertriglyceridemia, hypofibrinogenemia and coagulopathy were noted in 78%, 56% and 44%, respectively. All the patients were treated with intravenous doxycycline for an average duration of 9.5 days. Intravenous immunoglobulin and methylprednisolone were given in 33% and 22% cases, respectively. Complications like acute respiratory distress syndrome (ARDS) (p = 0.001) and MODS (p = 0.004) were significantly high in the HLH group. Younger age (<3 years), fever > 7 days, presence of convulsion, ARDS and MODS were the clinical predictors of scrub typhus-associated HLH.

CONCLUSION

HLH in scrub typhus infected children is being increasingly recognized. Younger age, prolonged fever, presence of convulsion, ARDS and MODS should alert clinicians of the risk of HLH. Treating the primary cause usually cures the disease and immunomodulator therapy need not be routinely administered.

Evaluation of Recombinant Type-Specific Antigens of Orientia tsutsugamushi Expressed by a Baculovirus-Insect Cell System as Antigens for Indirect Immunofluorescence Assay in the Serological Diagnosis of Scrub Typhus

Scrub typhus (ST) is a mite-borne rickettsiosis caused by the intracellular bacterium Orientia tsutsugamushi (OTS), which is classified as a biosafety level-3 (BSL-3) pathogen. For serological tests of ST, mouse fibroblast cells infected with the five prevalent serotypes of OTS in Japan are generally used as antigens for indirect immunofluorescence assay (IFA). In this study, Spodoptera frugiperda derived insect cell line (Sf9) cells infected with recombinant type-specific antigen (rTSA)-expressing baculovirus were used for IFA. The paired serum samples of 15 ST patients, 10 rickettsiosis patients, and 10 control individuals were used. IgM and IgG titers determined by the rTSA-based IFA were correlated with those determined by the OTS-infected cell-based IFA (R² = 0.7319 to 0.7956). Based on the criteria for serological diagnosis, such as a suitable cutoff for single serum samples (IgM ≥ 1:160) and/or a significant increase in IgG titers between paired sera (≥ 4-fold), all 15 ST patients diagnosed as positive with the OTS-infected cell-based IFA were also diagnosed as positive by the rTSA-based IFA, whereas all 10 rickettsiosis patients and 10 control individuals were not. Thus, the rTSAs, which can be prepared in BSL-2 laboratories, are efficacious for the serological diagnosis of ST.

Risk Factors for Mechanical Ventilation in Patients with Scrub Typhus Admitted to Intensive Care Unit at a University Hospital

Background

The purpose of this study was to evaluate the risk factors for mechanical ventilation in the patients with scrub typhus admitted to intensive care unit (ICU) at a university hospital.

Methods

We retrospectively selected and analyzed clinical data from the medical records of 70 patients (32 men, 38 women) admitted to the ICU with scrub typhus between 2004 and 2014. The patients had a mean±standard deviation age of 71.2±11.1 years and were evaluated in two groups: those who had been treated with mechanical ventilation (the MV group, n=19) and those who had not (the non-MV group, n=51). Mean ages of the MV group and the non-MV group were 71.2±8.3 years and 71.2±11.1 years, respectively.

Results

Significant differences between the two groups were observed with respect to acute respiratory failure (p=0.008), Acute Physiology and Chronic Health Evaluation (APACHE) II score (p=0.015), Sequential Organ Failure Assessment (SOFA) score (p=0.013), death (p=0.014), and ICU duration (p<0.01). Multivariate analysis indicated that the following factors were significantly associated with mechanical ventilation: acute respiratory failure (p=0.011), SOFA score (p=0.005), APACHE II score (p=0.011), platelet count (p=0.009), and lactate dehydrogenase (LDH) (p=0.011).

Conclusion

Thus, five factors-acute respiratory failure, SOFA score, APACHE II score, platelet count, and LDH-can be the meaningful indicators for mechanical ventilation for the patients with scrub typhus admitted to ICU.

Multiple eschars in scrub typhus

An eschar is highly suggestive of scrub typhus in a case of fever. Multiple eschars are rare in scrub typhus. We present a picture of multiple eschars in scrub typhus.

Pancreatitis in scrub typhus: a rare complication

Scrub typhus is a zoonosis transmitted by a trombiculid mite which introduces bacteria of Orientia tsutsugamushi by its bite. The acute febrile illness is characterised by eschar at the site of the bite with maculopapular rashes and local and/or generalised lymphadenopathy. The disease is endemic in the tsutsugamushi triangle. Sikkim, a small Himalayan north-eastern state, is also not unaffected where outbreaks of the disease have been reported. The clinical spectrum of the disease ranges from mild to fatal depending on the virulence of the bacterial strain, susceptibility of the host and promptness of the treatment. In severe cases, there can be multiple organ involvement. Pancreatitis is a serious and unusual complication of this disease, which was seen in our presentation. A 22-year-old man, diagnosed to have scrub typhus, developed pancreatitis in the second week of the illness and responded well to medical treatment.