Simultaneous Detection of Ascaris lumbricoides, Trichuris trichiura and Strongyloides stercoralis using Modified Stool DNA Extraction Method

Background and Objective: Soil Transmitted Helminth (STH) infection is diagnosed by using a conventional method like microscopy, egg numeration assay, serology based assay and egg culture. Polymerase Chain Reaction (PCR) has advantages over the traditional microscopy method as they are highly sensitive and specific. However, disruption of the hard eggs shell covering the STHs eggs may hamper the DNA extraction process. This study was carried out to compare the sensitivity of microscopy and conventional PCR techniques to detect A. lumbricoides, T. trichiura and S. stercoralis using modified DNA extraction technique in stool samples. Material and Methods: Prior to DNA extraction, the isolated eggs were subjected to floatation and sedimentation techniques were briefly boiled followed by freeze-thaw cycles. Around eight (n = 8) stool samples positive for STH were chosen randomly by microscopy were proceeded by PCR technique for identification of A. lumbricoides, T. trichiura eggs and S. stercoralis larvae. Results: The presence of A. lumbricoides and T. trichiura eggs were detected in all eight stool samples (100%) by microscopy examination while only six samples showed positive PCR amplification (sensitivity: 75%) for A. lumbricoides and two samples show positive PCR amplification (sensitivity:20%) for T. trichiura. On the other hand, there are no S. stercoralis were detected in all stool samples. Conclusion: Microscopy was proven to be rapid and inexpensive compare to PCR however, the additional study needs to standardize DNA extraction and conventional PCR protocol in order to increase diagnosis.