Parasite and the Circulating Pool- Characterisation of Leukocyte Number and Morphology in Malaria

Haematological changes are the most common complications encountered in malaria. There is significant correlation between several of the haematological parameters and the clinical profile, prognosis and mortality in malaria. White cell counts and differentials are among the most basic and primary investigations done in a patient presenting with fever of short duration.

This study analyzes the numerical and morphological changes in White Blood Cells (WBCs) in peripheral blood in patients with acute malaria in endemic region in an effort to get a picture of specific changes that could be identified by basic investigations.

This study was conducted in tertiary care hospital in a region endemic for malaria. EDTA anticoagulated venous blood samples from 600 patients diagnosed with vivax and falciparum malaria was analysed in Coulter counter LH 500 for the white cell count and differentials. Morphological changes were looked for in Leishman stained peripheral blood smear. Comparison with age matched healthy controls was done by ANOVA with Bonferroni test wherever applicable.

Patients with malaria showed significant leucopenia, neutrophilia, lymphocytopenia, monocytosis and eosinopenia. Lymphocytopenia was more severe in the falciparum group as compared to the vivax group. A higher White Cell Count (WCC) was seen in patients with higher haemoglobin levels in vivax group. The total leukocyte count showed a negative correlation with neutrophil count in falciparum malaria and a strong positive correlation with neutrophil count in vivax malaria. Band neutrophils were seen in 10% of the patients with falciparum and 1.1% of patients with vivax malaria. Atypical plasmacytoid lymphocytes were the only notable morphological finding.

Changes in leukocyte number and morphology in the peripheral blood are common. A combination of monocytosis and eosinopenia in a patient presenting with fever should alert the observer to the presence of malaria and should prompt a repeat blood smear examination in case of initial negative results for the parasite.