Secondary haemophagocytic lymphohistiocytosis associated with scrub typhus: A case report with a brief review of literature

Scrub typhus is a very important cause of acute undifferentiated febrile illness in the Asia-Pacific region. Haemophagocytic lymphohistiocytosis (HLH) is a rare and life-threatening condition characterised by widespread immune system activation, resulting in tissue damage throughout multiple organ systems. HLH is categorised into primary HLH, arising from intrinsic defects in lymphocytes and macrophages, and secondary HLH, primarily triggered by infections or connective tissue disorders. HLH is one of the rarest complications of scrub typhus. We present the case of a previously healthy young man who presented to our facility with a history of acute febrile illness. Clinical examination revealed an eschar and subsequent laboratory investigations confirmed the diagnosis of scrub typhus. The patient's haematological parameters showed pancytopenia, raising suspicion of this rare association. Confirmatory tests established the diagnosis of HLH, and the patient achieved an uneventful recovery following treatment for the underlying illness and supportive care.