Evaluation of Wondfo Rapid Diagnostic Kit for detecting Plasmodium ovale and analysis of influencing factors

OBJECTIVE: To evaluate the Wondfo Rapid Diagnostic Kit (Pf-LDH/Pan -pLDH) for detecting Plasmodium ovale and analyze the influence of parasitaemia, concentration and polymorphism of pLDH on the performances. METHODS: A total of 100 blood samples from P. ovale patients confirmed by PCR were detected with the Wondfo Rapid Diagnostic Kit according to the manufacturers'instructions. The parasitaemia was determined by the microscopic examination. The concentration of pLDH was measured by ELISA tests. The LDH gene of P. ovale was amplified by PCR and sequenced. The influence of these three factors on the positive rate was analyzed. RESULTS: The overall positive rate of Wondfo Rapid Diagnostic Kit was 70.0% (70/100). The positive rate was 27.3% for the samples with parasitaemia ≤ 500 parasites/μl and reached 75.0%-75.4% when parasitaemia > 500 parasites/μl. The positive rate was 6.7% for samples with a low pLDH concentration (A values ≤ 0.100) and reached 95.1%-100% at a high pLDH concentration (A values > 0.100). The results of sequence analysis indicated that all the samples could be divided into 2 types, P. o. curtisi and P. o. wallikeri. The gene homology of LDH between 2 types was 97%. There were 24 single nucleotide polymorphism (s) (SNPs) between 2 types, while only 3 SNPs were non-synonymous mutations. The homology of LDH amino acid sequences between 2 types was 99%; only 3 amino acids were different. The positive rates for P. o. curtisi and P. o. wallikeri were 73.1% (38/52) and 66.7% (32/48) respectively; there was no statistically significant difference (P > 0.05). CONCLUSIONS: The Wondfo Rapid Diagnostic Kit (Pf-LDH/Pan-pLDH) performs better than most of the similar products for the detection of P. ovale, and the positive rates are closely related to the parasitaemia and concentration of pLDH, while no related to the polymorphism of pLDH gene.