Background: The microfilarial nematodes, found mainly in blood circulation, form a special group of human and veterinary
parasitic diseases. Recently, the rapid nucleic acid based biosensors (NABs) have been established in our laboratory for the employment of a point-of-care diagnostic test. Herein, NABs involved in the exploitation of lateral flow dipstick (LFD), gold
nanoparticle (AuNP) and turbidity in combination with PCR and LAMP amplification for detection of filarial nematodes. The
validation of each NABs was investigated in comparison to that of standard detection methods using the same unknown blood
specimens.
Objective: To compare the sensitivity, specificity and accuracy of NABs with standard detection methods.
Material and Method: In this study, the microfilariae of Dirofilaria immitis was used as the representative model for filarial nematode. The PCR and LAMP primers were designed and synthesized according to the specific nucleotide regions of a small subunit gene of the parasite as well as the DNA probes. The fifty unknown blood samples were sent as a gift from Prasu
Arthorn Animal Hospital, Faculty of Veterinary Science, Mahidol University. The samples were tested by using PCR, PCRLFD,
PCR-AuNP, LAMP, LAMP-LFD, LAMP-AuNP, LAMP-turbidity and film blood smear. The efficacy of NABs was compared to a standard film blood smear in terms of sensitivity, specificity and accuracy.
Results: Upon detection of fifty unknown blood samples, LAMP-LFD assay presented 100% of sensitivity, specificity and accuracy. The data revealed that sensitivity, specificity and accuracy of NABs varied from 66.67-100.00% when compared to a film blood smear stained with Giemsa dye. The data clearly indicated that LAMP-LFD was a preferred choice for the use as a point-of-care NABs.
Conclusion: NABs were highly sensitive performing as a selective diagnostic tool that could be applied particularly as the
rapid screening tests for filarial nematodes hence as a recommended epidemiological survey.

Keywords: Filaria, Nucleic acid based biosensor, Lateral flow dipstick, Gold nanoparticle, Turbidity assay