Utility of nested polymerase chain reaction over the microscopy and immuno-chromatographic test in the detection of Plasmodium species and their clinical spectrum

Abstract

Though demonstration of Plasmodium parasite in peripheral blood on microscopy remains gold standard, it may miss some patients resulting in delay in instituting life-saving therapy. Studies on polymerase chain reaction (PCR), a highly sensitive and specific technique that also discriminates among different species of malaria parasite, are scanty. Hence, we aimed to evaluate the role of PCR in diagnosis and species identification of Plasmodium. Of 2186 febrile patients with clinical suspicion of malaria screened between July 2013 to February 2015, 561 patients fulfilled inclusion criteria. Microscopy, rapid diagnostic test (RDT) and PCR were performed to identify the parasite. Plasmodium was detected in 64/561 (11.40 %), 92/561 (16.40 %) and 78/561 (13.90 %) cases using microscopy, RDT and PCR, respectively. Of 78 positive cases by PCR, 47 (60.25 %) were confirmed as Plasmodium falciparum (P. falciparum), 28 (35.89 %) were Plasmodium vivax (P. vivax) and 3 (3.84 %) had mixed infections. Sensitivity and specificity of microscopy and RDT were 82.10 %, 100 % and 98.70 %, 96.90 %, respectively (p = 0.139). Of total 93 patients, 67 (72.04 %) were classified as complicated and 26 (27.96 %) were as uncomplicated. Creatinine (p = <0.001), conjugated bilirubin (p = 0.003) and total bilirubin (p = <0.001) level was elevated in complicated malaria along with renal (65 %) and liver dysfunction (25 %). In the present study, P. falciparum was responsible for 40/67 (59.70 %) cases of complicated malaria; P. vivax was also found in 17/67 (25.37 %) complicated cases using PCR. The findings highlight the alarming number of complicated vivax malaria in addition to falciparum. Moreover, PCR proved to be highly sensitive and specific test for detecting Plasmodium species.

Keywords: Complicated malaria; Parasitemia; Renal failure; Survival.