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Int Arch Med. 2014 Jun 21;7:31. doi: 10.1186/1755-7682-7-31. eCollection 2014.

Changes in full blood count parameters in leptospirosis: a prospective study.

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Tropical Medicine Research Unit, Faculty of Medicine, University of Colombo, 25 Kynsey Road, Colombo 08, Sri Lanka.
Institute of Biochemistry, Molecular Biology and Biotechnology, University of Colombo, Colombo, Sri Lanka.
Medical Research Institute, Colombo, Sri Lanka.
Faculty of Medicine, University of Kelaniya, Kelaniya, Sri Lanka.
Faculty of Science, University of Colombo, Colombo, Sri Lanka.



Leptospirosis presents diagnostic challenges to clinicians, in settings where other acute febrile illness are prevalent. The patterns of serial changes in haematological parameters in leptospirosis has not been evaluated previously.


Clinical and laboratory data were collected prospectively from patients with leptospirosis in two hospitals in Sri Lanka. Leptospirosis was diagnosed based on WHO clinical criteria with confirmation using Microscopic Agglutination Test titre > 400 or 4 fold rise between acute and convalescent samples. Full blood count parameters were analysed up to the 14(th) day of illness.


Data from 201 patients with leptospirosis were available. Leukocyte counts and absolute neutrophil counts showed a decline over the first 5 days of illness, then rose until the end of the second week. On day 3 of fever, the majority (75%) had normal leukocyte counts, and by day 5, leukocytosis was seen only in 38.1%; leucopenia was an uncommon finding. Lymphopenia was seen in over half on day 5, declining to just under a quarter of patients by day 10. Platelets declined over the first 6 days and then gradually rose. Thrombocytopenia was seen in nearly three-fourths of patients by day 5. Haemoglobin and haematocrit levels declined over the course of illness. Total white cell and neutrophil counts were higher, and haemoglobin and haematorcrit were significantly lower, in patients with severe disease.


Neither leukocytosis nor lymphopenia were prominent features, while thrombocytopenia was seen during the 3(rd) to 5(th) day of illness, with dropping haemoglobin levels. Neutrophilia and low haemoglobin levels appear to predict severe disease. These findings may be of use to clinicians in differentiating leptospirosis from other acute infections like dengue, and could help in predicting severe leptospirosis.


Leptospirosis; Lymphocytes; Neutrophils; Platelets

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