Repeated sampling improved the sensitivity of malaria microscopy in children under six years

Abstract

Objective Microscopy remains the gold standard for identification of malaria parasites. However, the sensitivity of malaria microscopy is low. This study evaluated the impact of repeated sampling up to 12 h in 177 children < 6 years with suspected malaria. Results The median age was 3 years (interquartile range, 2.0–4.0 years). Eighty-nine percent (158/177) presented with hyperthermia together with one or more of the following symptoms: chills, headache, sweating, fatigue, nausea, abdominal pain, vomiting, diarrhea and cough. Baseline microscopy confirmed malaria in 29.9% (53/177) of the suspects. Repeated testing at 6 and 12 h increased the positive detection rates to 35.0% (62/177) and 41.8% (74/177), respectively. Microscopy underestimated malaria diagnosis by 11.9% on single testing. Children showing classical signs of malaria but with initial negative parasitological reports should be retested between 6 to 12 h to confirm or rule out a diagnosis of malaria.

Malaria and typhoid fever coinfection among patients presenting with febrile illnesses in Ga West Municipality, Ghana

“…Malaria POC-RDT lacks sensitivity at low parasitemia levels below 50 parasite/ul of blood [12]. Only in severe clinical febrile illness are patients requested to do a Widal test.…”

Utilization of 18s ribosomal RNA LAMP for detecting Plasmodium falciparum in microscopy and rapid diagnostic test negative patients

“…When repeated testing was done at 6 hours and 12 hours after baseline testing, the positivity rates were 35% and 42%, respectively. This was because parasitemia at hour 6 was submicroscopic but at the 12 th hour, continuous and unchecked multiplication of the parasites yielded enough parasitemia to be detected microscopically [ 14 ]. During the same period, the positivity rate of mRDT increased from 42.9% at baseline testing to 47.5% 12 hours after baseline testing [ 14 ].…”

“…This was because parasitemia at hour 6 was submicroscopic but at the 12 th hour, continuous and unchecked multiplication of the parasites yielded enough parasitemia to be detected microscopically [ 14 ]. During the same period, the positivity rate of mRDT increased from 42.9% at baseline testing to 47.5% 12 hours after baseline testing [ 14 ]. It is obvious that a significant proportion of patients presenting with clinical signs of malaria may test positive for malaria either with microscopy or mRDT within 12 hours or more.…”

“…That nothswithstanding, PfHRP2 based kits are being rendered useless due to the increasing frequency of Plasmodium falciparum with mutations that make them incapable to produce the HRP 2 protein, the main marker the majority brands of mRDTs are manufactured to detect [ 6 , 9 , 10 ]. In Ghana [ 11 – 13 ] and elsewhere [ 11 , 14 , 15 ], various frequencies of P . falciparum with HRP2 gene deletions have been recorded, which result in false negative mRDT testing based on HRP2.…”

“…falciparum was detected in patients that were declared negative for malaria microscopy and mRDT, using Plasmodium 18s rRNA LAMP. This study is essential because a previous study detected malaria parasites in about 12% of patients that were initially tested negative for malaria with repeated sampling [ 14 ]. Therefore, early detection of the Plasmodium parasite in patients presenting with classical signs of malaria at baseline is essential for prompt management.…”