Human Monocytic Ehrlichiosis (HME) can cause multi-organ dysfunction syndrome (MODS) and rarely secondary hemophagocytic lymphohistiocytosis (HLH). Here we present an immunosuppressed patient who developed clinical signs of meningoencephalitis and secondary HLH due to Ehrlichia chaffeensis (E. chaffeensis).

CASE: A 66-year-old man with a history of adult onset stills disease was admitted with fever, rigors, malaise, and worsening mentation for a week. He was on immunosuppression following a renal transplant two weeks before admission. He was started on empiric antibiotics for treatment of meningoencephalitis. Cerebrospinal fluid (CSF) analysis was not performed given severe thrombocytopenia. Electroencephalography revealed generalized slowing with no seizures and imaging of the brain was unremarkable. Pertinent laboratory workup revealed elevated ferritin, triglycerides, lactate dehydrogenase and a bone marrow biopsy demonstrating hemophagocytosis and positive serum E. chaffeensis on polymerase chain reaction (PCR) testing. He was subsequently diagnosed with hemophagocytic lymphohistiocytosis (HLH) secondary to E. chaffeensis in the setting of underlying immunosuppression. He was started on high dose steroids, however he deteriorated clinically requiring mechanical ventilation and pressor support. He was made comfort care per family and eventually passed away on the third week since admission.

Secondary HLH is often triggered by infection, malignancy or autoimmune disease. HME caused by E. chaffeensis is an uncommon endemic tick-borne infection in certain parts of the United States. It typically causes a mild-moderate illness but can also lead to MODS and rarely secondary HLH. Specific laboratory tests for HME include DNA PCR, acute and convalescent antibody assays. Positive CSF testing is reported in less than 50% of the cases. Doxycycline is the drug of choice for HME. High clinical suspicion and treatment of the infection can be life-saving with an otherwise dismal prognosis of secondary HLH.