Automation of DNA sample preparation for PCR-based surveillance for onchocerca volvulus transmission

Detection of Onchocerca volvulus larvae in vector populations is of prime importance for the assessment of the effectiveness of onchocerciasis control programs. The genome of Onchocerca species has a unique 150 bp repeat that can be amplified by PCR. The O.volvulus DNA probes can detect these by enzyme-linked immunosorbent assay (O-150 PCR-ELISA). This study optimizes DNA extraction method based on paramagnetic particles (Promega Maxwell16®) and compares it with the phenol-chloroform (P-C) method to estimate transmission parameters in a Mexican endemic community for onchocerciasis. One infected body and head were detected by PCR-ELISA in a pool of 49 and 149 uninfected bodies and heads, respectively using the paramagnetic method. At community level, three head pools were positive (ps=50; p=1.054; 95% confidence intervals CI=0.149-2.163) when using the P-C method and five head pools were positive (ps=100; p=1.698; 95% CI=0.456-3.135) when using the paramagnetic method. Similarly, twelve body pools were positive (ps=50; p=3.784; 95% CI=1.891-6.075) when using the P-C method and seven body pools were positive (ps=100; p=2.354; 95% CI=0.834-4.064) with paramagnetic method. Both methods produced statistically similar estimates of the infection and infective rates. Although the P-C method is less expensive than paramagnetic method, the latter is error-free, saves time, and less-toxic. Paramagnetic method could supplement the more tedious P-C method to study large populations of flies in short time with high accuracy.