Detection of Leishmania in human blood and tissue exudate ingested by Tunga penetrans

Abstract

Communities in Uganda are experiencing a multiparasitism, blood microscopy often reveals Leishmania and microfilaria in patients with anaemia, haemorrhage and splenomegaly. Many are likely asymptomatic and probably exposed to insect vectors. We examined the blood and tissue exudate ingested by Tunga penetrans, from relatively healthy eastern Ugandans who had been afflicted by sand fleas in 2010. Comparison was thereafter made with Giemsa-stained blood and bone marrow aspirate smears from patients admitted to Mulago National Referral Hospital. In histology preparations of formalin-preserved paraffin-embedded enucleate stained with haematoxylin and eosin, were cross sections with columnar lining containing a pink substance. Within the substance were numerous lobular and circular organelles, representing nuclei of polymorphonuclear and mononuclear white blood cells. Clustered about the nuclei were translucent spheres containing two spots; one large and dark, the other small and red. No microfilaria were seen. In patients’ blood smears, where microfilaria were also demonstrable, the spheres clustered inside monocytes and in bone marrow aspirate smears they were Leishman-Donovan bodies. The findings, besides indicating an inflammatory reaction of the host, implied a cutaneous and/or systemic leishmanial infection. Persons with Leishmania in their body fluids can infect female sand flies or develop visceral, cutaneous or mucocutaneous disease.