[Clinical analysis of scrub typhus-associated hemophagocytic syndrome]

To analyze the clinical manifestations and intervention against fulminant scrub typhus-associated hemophagocytic syndrome.

The medical records for the onset time of hemophagocytic syndrome, the clinical course, the chest radiographic findings, laboratory data, antibiotic therapy, clinical outcome and its prognosis were retrospectively reviewed.

(1) Four patients were diagnosed as scrub typhus based on clinical manifestations only, while 15 patients met the criteria of laboratory diagnosis. All 19 patients with scrub typhus had hemophagocytic syndrome. Eschar lesion was identified in 12 patients, 7 patients were described as an ulcer. A seasonal pattern (78.9% from June through September in 15 patients) was observed. Clinical misdiagnosis was common (all 19 cases). There were 9 patients with admitting diagnosis of scrub typhus, 10 patients were not diagnosed as scrub typhus after admission. In 5 cases within 3 days after admission diagnosis was corrected as scrub typhus. Until discharge from the hospital, 5 cases were not diagnosed with scrub typhus. In this study, the length of time from the illness onset (beginning of fever) to the occurrence of clinical symptoms was (9 ± 4) days. (2) All 19 patients had changed AST levels (149 ± 37) U/L, albumin levels (23 ± 4) g/L, C-reactive protein levels (103 ± 51) mg/L, and platelet count (48 ± 41) × 10⁹/L; bone marrow aspiration revealed in 16 patients marked hemophagocytosis. Weil-Felix agglutination test revealed positive results in 6 of 15 cases. Diagnostic IFA results were positive for 14 patients; 19 patients had interstitial pneumonitis and 17 patients had pleural effusion. (3) Five cases with failure to diagnose the disease had ineffective antibiotics treatment (imipenem or β-lactam-based regimens). These patients did not receive appropriate treatment with antibiotics against scrub typhus. Fourteen patients with admitting diagnosis of scrub typhus were successfully treated with appropriate antibiotics, 8 cases with chloramphenicol, 3 cases with azithromycin, and in 3 patients (2 cases of azithromycin and one case of erythromycin), therapy was then switched to chloramphenicol. Four patients were treated with methylprednisolone and 10 patients with dexamethasone. (4) During their hospitalization, the clinical course in five cases with failure to diagnose the disease rapidly developed and progressed to the life-threatening MODS, four of five cases died. However, the course in 14 patients were relieved and did not progress to MODS.

The diagnosis of scrub typhus was frequently delayed, the early course of scrub typhus could be associated with hemophagocytic syndrome. Serious complications of MODS generally occur without antibiotic treatment. Scrub typhus-associated hemophagocytic syndrome should be taken into consideration among patients with acute systemic febrile illness, significant increases in levels of CRP, hypoalbuminemia, thrombocytopenia, splenomegaly, pneumonitis with pleural effusion, especially those with suspected exposure history. It was not easily recognized without careful observation and was present for a few days in each patient.