de Silva NL, et al. - Researchers investigated the blood smear changes as a potential tool to aid in the diagnosis of leptospirosis. In this work, haematologists blinded to the diagnosis reported on blood smears prepared from patients with leptospirosis, dengue and sepsis within the first 5 days of illness. They recognized the combination of reactive lymphocytes with toxic neutrophils or neutrophil leucocytosis as highly suggestive of leptospirosis. Findings thereby suggest that peripheral blood smear findings could assist in differentiating leptospirosis from other common acute febrile illnesses.