Performance of ParaHit and OptiMAL tests in the diagnosis of Malaria in Mwanza, Southwest Tanzania.
Background: Rapid malaria diagnostic tests (RDTs) are non microscopic tests that provide a rapid detection of malaria parasites in infected individuals; they are simple and less technical demanding. However they have low detection thresholds particularly in low parasitaemia.
Objectives: To compare and evaluate the performance of ParaHit and OptiMAL tests for detection of malaria infections with routine microscopy.
Materials and Methods: Blood samples from study participants were obtained after their informed consent and tested for malaria parasite infection for the two RDTs according to instructions from the manufacturers, blood films were made and stained with Giemsa for microscopy.
A total of 243 individuals participated in the study with a median age of 22.0 yrs (range 0 -75yrs). Microscopy had a higher detection rate of 19.7% (48/243) as compared to ParaHit 4.5% and OptiMAL 3.7%. Low sensitivity of 21.2% and 17%, but high specificity of 99.4% with both ParaHit and OptiMAL tests were respectively obtained. Of all positive blood slides for P. falciparum malaria, 78.7% of these smears had low parasite density ranged between 80 -720 parasite/µl of blood. These slides were negative for malaria parasite based on both RDTs. Over 80% of study participants who reported fever had negative blood slides for malaria parasites by microscopy, but 44.7% among those who reported no fever had positive blood slides for P. falciparum Malaria. Study participants who reported to have fever and high parasite density above 720 parasite/µl were likely to be positive by both RDTs (OR= 6.8), P= 0.031529.
The overall performance of both RDTs in detecting asexual P. falciparum was low as compared to microscopy and their performance were highly affected with parasite density calling for further evaluation studies before its wide use in peripheral health facilities in order to minimize potential severe consequences.