Comparison of conventional methods for diagnosis of visceral leishmaniasis in children of the Center-West Region of Brazil

In Brazil, sophisticated techniques currently employed for diagnosis of visceral leishmaniasis, such as polymerase chain reaction-based assays, are only available in major research centers, whereas conventional methods are still used in many areas where the disease occurs. In the state of Mato Grosso do Sul, in the country's Center-West Region, visceral leishmaniasis has recently emerged in many cities, and duration of the disease, from the onset of symptoms to diagnosis, has been short. Considering that results of diagnostic tests may depend on the phase of the disease, we compared direct examination of bone marrow aspirates (BMAs), BMA culture, and serology by Indirect Immunofluorescence Antibody Test (IFAT) for diagnosis in children, according to time of evolution (< 30 days or >30 days) and to spleen size (< 5 cm or > 5 cm) at admission. Duration of the illness did not interfere with test positivity: direct smear examination and IFAT were positive in more than 80 percent of patients, as was culture in around 60 percent. Results of positive microscopy, however, where predominant in patients with larger spleens. Thanks to the association of traditional techniques, only a few patients had to begin a treatment trial without confirming the diagnosis. Conventional methods for diagnosis of visceral leishmaniasis are still indispensable in our region, and training professionals in basic techniques should be incremented. The highest sensitivity in laboratory diagnosis among the cases investigated was that obtained with a combination of BMA direct examination and IFAT, nearing 100 percent.

Hematopoietic features and apoptosis in the bone marrow of severe Plasmodium falciparum-infected patients: preliminary study.

The mechanism of anemia in severe falciparum malaria is still not completely understood. The purpose of this study was to determine whether apoptosis in the erythroid lineage causes anemia in falciparum malaria. Bone marrow aspirated from 8 severe falciparum malaria patients, 3 normal volunteers and 5 retrospective normal bone marrow smears were investigated. By light microscopic study, 5 of 8 hyperparasitemic patients had hypocellular bone marrows and erythroid hypoplasia, whereas the other 3 patients had normal cellularity. The mean myeloid : erythroid ratio of these 5 patients was significantly (p < or = 0.05) higher than normal. Apoptosis of bone marrow nucleated cells (BMNC) could be determined from the exposure of phosphatidylserine (PS) on the cell membrane but not DNA fragmentation (180-250 bp) or ultrastructural morphology. The percentages of apoptotic BMNC and apoptotic erythroid cells in bone marrow from each patient and controls varied from low to high, and were not associated with parasitemia. This study suggests that destruction of erythroid lineage, particularly through apoptosis regulation, cannot solely account for anemia in falciparum malaria.