Survival period, infectivity and morphological composition of Trypanosoma brucei maintained at varying intervals in refrigerator and ambient temperature

Abstract

Infected blood was collected from a ram experimentally infected with Trypanosome brucei at a parasitaemia of three parasites per filed on Giemsa stained blood film and two millilitre was dispensed each into 16 sample bottles containing ethylene diamine tetra acetic acid (EDTA). Blood was also collected from the animal into sample bottles without anticoagulant centrifuged and 2mls of serum obtained dispensed each into 16 clean sample bottles. The bottles were labelled and maintained for intervals of 6, 12, 18, 24, 30, 48, 60, 72, 96, hours on the laboratory bench and in refrigerator (4°C). At the end of each maintenance period (hours), three clean albino mice were intraperitoneally infected with 0.2ml of the sample. Five mice served as uninfected controls. Parasitaemia was monitored daily by wet mount technique using the tail blood. Giemsa stained blood films were also prepared and examined. Blood sample maintained on the laboratory bench and in refrigerator for up to 30 and 48 hours respectively and serum sample on the bench and refrigerator for up to 30 and 48 hours respectively and serum sample on the bench and refrigerator for up to 12 and 24 hours respectively were infective for the mice inoculation test. Parasites in refrigerated blood sample were still alive after 6 days but were unable to initiate infection in mice. Samples kept on the bench showed shorter prepatent period (21.0days) higher peak parasitaemia (15-20 parasites per field) and higher population of slender forms. Refrigerated blood and serum samples showed longer prepatent periods (41.0 days) lower peak parasitaemia (4-5 parasites/field) and more of the intermediate forms.

Nigerian Journal of Parasitology Vol. 25, 2004: 39-44