Efficacy of Histochemical Staining Techniques in the Detection of Plasmodium falciparum Histidine-Rich Proteins in Blood of Children with Malaria

Abstract

Objective: Falciparum malaria predominates in sub-Saharan Africa and children below
 five years are the most vulnerable. Giemsa-stained microscopy is the gold
 standard in malaria diagnosis. Diagnosis with rapid diagnostic test (RDT) kit
 is also common and over 80% of available malaria RDT kits is Plasmodium falciparum histidine-rich
 protein 2-based (Pfhrp2). However, these histidine-rich protein 2-based kits
 have been observed to give false positive and negative results due to
 persistent antigenemia and low parasitaemia respectively. Thus, the methods of
 Pauly, Perls, and Means & Feeney were adopted to explore the advantage of
 using microscopy for specific detection of these histidine-rich proteins and
 their usefulness in detecting low parasitemia in children. 
 
 Methods: Children
 aged 0-5 years (n=200) visiting three hospitals and private laboratories in
 Calabar were recruited. Whole blood samples were tested with CareStart Malaria
 HRP2-based kit, and blood films were made and stained with Giemsa, Pauly, Perls
 and Means & Feeney for microscopy.
 
 Results: The
 sensitivity and specificity were Giemsa (56.4%, 79.8%), Means & Feeney
 (52.5%, 77.8%), Perls (47.5%, 85.9), Pauly (45.5%, 86.9%), and RDT (23.8%, 96%).
 Pauly method had the highest area under the curve of 0.830 while RDT method had
 the lowest of 0.661. Among the positive cases low parasitemia detected by the
 histochemical methods was Perls 36 (75%), Pauly 32 (69.6%), and Means &
 Feeney 34 (64.2%), and for Giemsa method 40 (70.2%).
 
 Conclusion: Pauly method was the most accurate. All three methods
 were sensitive in detecting low parasitemia. These diagnostic methods are
 useful in malaria diagnosis in this endemic population. J Microbiol Infect Dis 2018; 8(2):55-60