Challenges in Laboratory Diagnosis of Malaria in a Low-Resource Country at Tertiary Care in Eastern Nepal: A Comparative Study of Conventional vs. Molecular Methodologies

Abstract

For ongoing malaria elimination programmes, available methods such as microscopy and rapid diagnostic tests (RDTs) cannot detect all malaria cases in acute febrile illness. These methods are entirely dependent on the course of infection, parasite load, and skilled technical resources. Our study objectives were to estimate the performance of light microscopy and a RDT as well as real-time PCR for the detection of the Plasmodium parasite. Altogether, 52 blood samples collected from patients with acute febrile illness were tested by microscopy, RDT, and real-time PCR. The results were compared in terms of sensitivity and specificity. Microscopy detected the malaria parasite in 5.8% of the blood samples whereas 13.5% were detected by the RDT and 27% by real-time PCR. Considering real-time PCR as the gold standard method, microscopy had a sensitivity of 21.4% and a specificity of 100%, and the RDT had a sensitivity of 28.6% and a specificity of 92.1%. Microscopy together with the RDT successfully detected malaria positive cases in blood samples of Ct value below 20, but both were unable to detect malaria cases between 26–40 Ct value ranges amplified by real-time PCR. Despite various diagnostic tools being available, microscopy still remains the method of choice for diagnosis, while the RDT is user-friendly when applied at the point of care. However, our preliminary results emphasize the need to implement the test with higher sensitivity and specificity in the context of a malaria elimination programme. Such programmes can be a crucial opportunity to understand the species prevalent in a low-endemic region. However, these results should be further verified with a large cohort study to document the submicroscopic infection.

Evaluation of performance for malaria diagnosis in health facilities by five provincial reference laboratories of China

“…The inconsistency between microscopy and nPCR confirmation at provincial reference laboratories was mainly in determining malaria positivity or negativity. Explanations for this included low parasite density affecting the ability to detect malaria by microscopy ( 32 ), some patients with illness history self-medicated after their return from overseas resulting in low detectability of viable parasites in the bloodstream by microscopy, or non-optimal sampling time of blood smears and samples for diagnosis ( 33 ). In addition, some differences in reference laboratory confirmatory diagnosis showed inconsistencies between mixed and single infections, as well as between P. ovale and P. vivax .…”

A systematic review and meta-analysis on sub-microscopic Plasmodium infections in India: Different perspectives and global challenges

“…Microscopy revealed significantly less Plasmodium infected individuals than detected by PCR in these reports. 47 , 48 , 49 , 50 SMIs appear to be a serious impediment to malaria elimination operations in such malaria-endemic countries like Myanmar, Bangladesh, and Nepal. These results demonstrated the importance of molecular diagnostic methods in epidemiological surveys, as microscopy's sensitivity did not even detect half of the infected individuals.…”

Fast and accurate automated intestinal parasites egg detection and classification from images based on YOLOv5 deep convolutional neural network

“…More than 100 species of intestinal parasites replicated daily after hatching at a rate of 200,000 eggs per day. Manual light microscopy is the gold standard for the diagnosing of the parasite diseases 2,3 . However, microscopybased parasite species recognition and quanti cation is complicated, labour-intensive, and timeconsuming, requiring a microscope and experts 4,5 and is also challenging for human experts to examine microscopic images because of the variation and uncertainties in morphological features like shape, staining color and density of parasite species.…”