RESUMO
Background: Malaria diagnosis presents a challenge to all laboratories. In malaria-endemic areas, there is a need for rapid, sensitive and cost-effective method to effectively screen all samples, especially when the workload is very high. Various hematology analyzers have been investigated for detection of malaria in the past. Here, we present our experience of malaria detection in a cancer hospital where a large number of complete blood count requests are received either before or during chemotherapy. Fever, being a very common symptom in cancer patients, causes a suspicion of malaria. Aim: This study was conducted to assess the usefulness of hematology cell counter, viz. WBC-DIFF and WBC/BASO scatter plots and the flaggings generated in malaria-positive cases. The occurrence of pseudoeosinophilia as reported by previous studies was also assessed. The parasitic index was determined and its correlation with the abnormalities found on the Hematology analyzer was also studied. Materials and Methods: Blood samples were collected from 80 out-patient department and inpatients with various solid as well as hematological malignancies, who presented with acute febrile illness during September 2010 and January 2012, and for whom complete blood cell analysis and peripheral smear for malaria parasite had been requested. Results: Of the 80 patients who presented with fever and suspicion of malaria, 29 patients were positive for malaria and 10 cases were diagnosed incidentally by the findings on the cell counter and were confirmed by Giemsa-stained blood smears. The sensitivity and specificity of the abnormalities detected in the WBC-Diff channel in detecting malaria is 82% and 100% respectively. Using WBC-BASO channel abnormality for initial diagnosis the sensitivity and specificity is 50% and 92.5% respectively. The sensitivity and specificity with respect to pseudoeosinophilia is 18% and 100% respectively. The most common WBC and PLT flags were leukopenia, atypical lymphocytes, lymphopenia, WBC abnormal scattergram, platelet clumps, thrombocytopenia, platelet abnormal distribution flag. Conclusion: The instrument provides significantly valuable diagnostic parameters in detecting acute Plasmodium vivax malaria; however, it is not very useful for acute falciparum malaria infection. It is suggested that the laboratories using the hematology analyzers should be aware of such specific parameters, even in the absence of a clinical request.
RESUMO
In Korea, the incidence of malaria has been increasing in the civilian population and in the areas previously considered as noninfected. Malaria can be suspected based on the patient's symptoms and the physical findings at examination. However, for a definitive diagnosis to be made, the malaria parasites or their components must be demonstrated by laboratory tests, which will take time and require expertise. Since general screening tests, such as a complete blood cell count, are always done for patients with a fever, it can be expected that the attention of laboratory hematologists drawn to any abnormalities found in automated hematology analyzers can help reduce delays in the diagnosis of malaria even if such a diagnosis was not initially considered. We report three cases of malaria that had thrombocytopenia and pseudoeosinophilia shown in the Sysmex XE-2100 (TOA Medical Electronics, Kobe, Japan) automated hematology analyzer. It is feasible that the pseudoeosinophilia presented as a result of hemozoin-containing white blood cells may contribute to the diagnosis of malaria, especially for patients unsuspected of the disease.