Low Malaria Parasite Density is Associated with Severe Malaria in Children in Eastern Uganda: a cross sectional study

Abstract

Background: In high malaria transmission settings, there is paucity of data on the relationship between parasite density and severe malaria forms. In patients with severe malaria, we characterised parasite density for the different clinical spectra and assessed its association with mortality. Methods: This was a cross sectional study conducted as part of the Malaria Epidemiological, Pathophysiological and Intervention studies in Highly Endemic Eastern Uganda code named TMA 2016SF-1514-MEPIE Study, at Mbale Regional Referral Hospital in Eastern Uganda. Children aged 2 months to 12 years with positive P. falciparum malaria on microscopy and who fulfilled the WHO 2014 clinical surveillance criteria for severe malaria were enrolled into the study. Parasite density was determined by multiplying the parasite count acquired from microscopy by the patients WBC count (parasite count*WBC count/200) and classified as hyperparasitaemia when parasite density was 10% or > 250,000 parasites/μl. Data were analysed using Stata 15 and P-value of 0.05 at 95% confidence intervals were used to show significant associations. Results: We screened 897 children, of which 377 were eligible for recruitment with severe malaria forms according to the WHO definition. Of these, 76.9 % (290/377) presented with prostration, 55.4% (209/377) with jaundice, 48.5% (183/377) with severe anaemia, and 46.7% (176/377) with haemoglobinuria (dark or black urine). Cerebral malaria constituted 7.4% (28/377) with 64.3% of the cases among under 5 year olds, 23.1% (87/377) had impaired consciousness, 8.2% (31/377) had respiratory distress, 15.4% (58/377) had acidosis, and 13.8 % (52/377) had renal impairment. Mean parasite density was 136,000 parasites/µl (range 36- 2,791,400 parasites/ µl). The Highest parasite density was 386,000 parasites/ µl in hypovolemic shock and the lowest parasite density was 54,917 parasites/ µl in spontaneous bleeding. Over-all mortality was 3.4 % CI (1.3-5.5). Conclusions: There were low parasite densities in the patients with severe malaria in this area. The meanparasite density was 136,000 parasites/ µl. Highest parasite density was 386,000 parasites/µl in hypovolemic shock and the lowest was 54,917 parasites/µl in spontaneous bleeding. No association with mortality was found.