Evaluating the potential of using urine and saliva specimens for malaria diagnosis in suspected patients in Ghana

BACKGROUND: This study aimed at detecting PfHRP2 and pLDH malaria antigens in urine and salivary specimens of suspected malaria patients using RDT kits, and identifying factors influencing the detection of these antigens. METHODS: Malaria rapid test kit (SD Bioline RDT kit) was used to detect malaria antigens, PfHRP2 and pLDH, in blood, urine and saliva samples received from patients suspected of malaria. Subsequently, malaria parasitaemia was determined. From the same patients, body temperature readings and haemoglobin concentrations were recorded. Also, micro-haematuria and saliva occult blood were determined. Relative to blood, the sensitivities and the performance of urine and saliva as alternative samples were evaluated. RESULTS: A total of 706 suspected malaria patients provided all three specimens. Prevalence of malaria by microscopy and RDT was 44.2% and 53.9%, respectively. Compared to blood, the sensitivities of urine and saliva were 35.2% and 57.0% respectively. Haemoglobin concentration < 9.9 g/dL, body temperature > 38.7 °C and occult blood influenced the detection of malaria antigens in both urine and saliva. Furthermore, the antigens were not detected in urine and saliva when parasitaemia was < 60,000 parasites/µL and < 40,000 parasites/µL, respectively. CONCLUSION: Saliva, with or without blood contamination, was found to be more efficient that urine samples. Therefore these non-blood specimens have the potential to be used as non-invasive samples for malaria diagnosis. However, this approach is useful in severe to moderate anaemia, hyperthermia, parasitaemia > 60,000 parasites/µL and samples contaminated with blood.