Comparative assessment of urine-based RDT in malaria diagnosis during febrile and non-febrile conditions

Abstract

Malaria due to Plasmodium falciparum is a life-threatening disease that requires prompt diagnosis for its management. As a result, Rapid Diagnostic Test (RDT) was provided because it is simple to use and provides quick result without the need for good microscopy equipment and operators. Although blood is the specimen most frequently used for RDT, urine has been suggested as an alternative specimen. The study compares the performance of Urine-based RDT (uRDT) with Microscopy and Blood-based RDT (bRDT) in malaria diagnosis. This study was conducted using blood and urine specimens collected from 350 humans that attended Primary Health Centres at Amansea and Igbariam in Awka North and Anambra East LGAs of Anambra State respectively. Care-start^® and Fyodor^® test kits were used for malaria rapid diagnosis while Giemsa stained thick and thin blood films were used as standard. Malaria parasite prevalence in the study was 57.1% by microscopy, 22.0% by bRDT and 11.1% by uRDT (p<0.05). Under febrile condition, prevalence records were 83.2% by microscopy, 34.9% by bRDT and 16.8% by uRDT (p<0.05). Compared to the non-febrile group, the Odd Ratio of malaria in febrile group is 8.16, 3.77 and 2.69 for microscopy, bRDT and uRDT respectively. In both (febrile; non-febrile) conditions, the sensitivity of blood based RDT (39.5%; 28.9%) is higher than that of uRDT (18.5%; 17.1%). However, the specificity of the uRDT (92.0%; 99.2%) is higher than that of the bRDT (88.0%; 97.6%). At malaria parasite count of ≤ 120 parasites/μl of blood, (>120 to < 430) parasites/μl and ≥ 430 parasites/μl of blood, bRDT recorded increasing higher prevalence values than the uRDT that followed the same pattern. There was significant weak positive correlation between malaria parasite density of microscopy and the RDTs. Among the febrile and non-febrile subjects who tested positive for malaria using uRDT, 92.0% and 71.4% respectively had thick line shown (p>0.05). Using the Receiver-Operator Characteristic (ROC) curves, the uRDT can be used to diagnose malaria infection even when the parasitaemia level is as low as 260 parasites/μl of blood at 76.9% sensitivity and 82.5% specificity. bRDT can detect malaria parasites at the same level but with sensitivity level of 85.9% and specificity level of 77.5% for febrile and non-febrile conditions. In conclusion, the uRDT followed similar pattern of malaria parasite diagnosis with microscopy and bRDT though with lower performance.

Keywords: Malaria diagnosis; urine-based RDT; blood based RDT; microscopy; febrile; non-febrile