Could the Level in Parasitaemia of <i>Plasmodium</i> Determine Sensitivity to Various Diagnostic Tests?

Abstract

The discovery of Plasmodium parasites and its incrimination as the principal cause of malaria in humans has continued to excite researchers towards inventing possible easier methods of diagnosing and identifying these pathological agents in order to mitigate, control and eliminate its continuous scourge to humanity. Currently, three diagnostic methods have been proposed, but agreements as to whether the level of parasitaemia in an individual could connote likely confirmations in the three methods i.e. gold standard, RDTs' and PCR/NESTED PCR, have continued to be a subject of debate. To lay to rest the debate as reported in many studies, we collected blood samples from 100 symptomatic patients who reported to the Jos-Nigeria hospital and using the gold standard methods, we were able to confirm that 30 (30%) samples out of the 100 blood samples collected were positive to P. falciparum, chiefly recorded among duffy-negative Africans. Excited with our findings, we prepared the thick blood films for each sample and used it to estimate the levels of parasitaemia (parasites density) per μl of blood (i.e. 1+; 2+; 3+ and 4+) per 100 high power fields (|HPF). We then subjected the individually confirmed parasite density samples to the other two methods i.e. Rapid Diagnostic Test (one-step RTD and optimal-IT® RDT) and to molecular assay (PCR and the nested PCR). Interestingly, of the 30 positive samples, 18 (60%) were confirmed positive to the one-step and optimal-IT® RDTS, while 3 (30%) out of the 10 (100%) samples of various parasite density subjected to molecular as-How to cite this paper: Goselle, O.N.,

Prevalence of malaria and comparative diagnostic performance of malaria rapid diagnostic test against microscopy in Nasarawa-west senatorial District, Nasarawa, Nigeria

“…The "plus system" was used to record the levels of parasitaemia (parasite density) as follows: 1+ = 1 -10 parasites per 100 oil-immersion thick smear field; 2+ = 11 -100 parasites per 100 oilimmersion thick smear field; 3+ = 1 -10 parasites per thick smear field; 4+ = >10 parasites per thick smear field. The level of parasitaemia was graded as low (< 1000 parasites/µl of blood), moderate (1000-9999 parasites/µl of blood) and severe (≥ 10,000 parasites/µl of blood) [15,16,17,7,18] .…”