Every Nook and Cranny

If dengue does indeed explain the entire presentation, defervescence should have occurred by the time the blood cultures and serologic studies returned. Also, by that time, the patient would be expected to demonstrate evidence of improvement, barring the appearance of the serious complications of dengue hemorrhagic fever/dengue shock syndrome. Should fever persist and signs of recovery fail to materialize, the possibility of a superimposed process will need to be considered. Of note, the sensitivity of Leptospira serology early in the course of illness is low, and leptospirosis is thus not yet excluded.

A presumptive diagnosis of severe dengue fever was made, based on evidence of pulmonary edema and sepsis. The patient was managed conservatively with oral fluid restriction, low dose of diuretics, and supplemental oxygenation. The patient was also given levofloxacin for possible legionellosis. Despite these therapies, the patient had no improvement in 24 hours. His tachypnea increased, and his measured PaO2 to FIO2 (P:F) ratio decreased to 230 from 285 on admission. This prompted the initiation of BiPAP at 10 cm H2O inspiration PAP and 5 cm H2O expiration PAP. However, he did not tolerate BiPAP, and his P:F ratio decreased to below 200.

The patient was transferred to the intensive care unit and underwent elective intubation with mechanical ventilation. Axial and coronal computed tomography of the thorax (Figure 1A and 1B, respectively) showed extensive ground-glass opacities and consolidation sparing the nondependent portions of the lungs. On physical inspection, a round, well-defined, painless black lesion surrounded by erythema was noticed in the right axilla (Figure 2). The rest of the examination findings were unchanged.

The discovery of eschar in the axilla provides a “pivot point” in determining the cause of the patient’s illness. This finding appears to point, with high specificity, toward rickettsia as the explanation of the patient’s disease, and this is most likely to be scrub typhus. The report of a positive dengue IgM may represent concurrent infection or may simply reflect a recent infection in an area that is highly endemic for dengue. Although most of the patient’s clinical presentation could be attributed to dengue, multiple features including the leukocytosis, myocarditis, and elevated bilirubin are more likely to be seen in scrub typhus. In any event, dengue cannot satisfactorily explain the eschar.

No mention has been made to the initiation of doxycycline thus far; this agent needs to be started promptly. Polymerase chain reaction (PCR) testing for scrub typhus should be ordered if available; if not, acute and convalescent serology may be obtained.

Given the finding of axillary eschar, the patient was diagnosed with scrub typhus. Doxycycline 100 mg by nasogastric tube twice a day was initiated. The patient began to show marked symptomatic improvement. His P:F ratio improved, and he was successfully weaned off and extubated after 24 hours. Postextubation, he was kept on BiPAP for 12 hours. He was transferred out of the ICU and monitored for 72 hours. With therapy, his cytopenias, liver and renal function, and ECG normalized. Indirect immunofluorescence assay for scrub typhus returned positive at a dilution of > 1:512. PCR assay targeting the 56 kDa region of Orientia tsutsugamushi was also positive. Repeated TTE showed an LVEF of 65%. He was subsequently discharged with oral doxycycline and a plan to complete a course of 14 days on an outpatient basis. The final diagnosis was scrub typhus with myocarditis leading to acutely decompensated heart failure with reduced ejection fraction.