Filter paper for preserving insects, bacteria, and host reservoir DNA.

Sir, the recent report on “Utility of filter paper for preserving insects, bacteria, and host reservoir DNA for molecular testing” is very interesting (Karimian et al. 2011). Karimian et al. (2011) reported that “The filter paper method is a simple and economical way to store, to preserve, and to distribute DNA samples for PCR analysis.” Many facts should be discussed. First, this work is only a simple retrospective observational study. There is no economic analysis. No data on the cost, hence, it might not be possible to conclude that the technique is an economical way. Second, Karimian et al. (2011) concluded on preservation. This might be an extrapolating summary. There must be the proposed mechanism how the simple filter paper can preserve the sample. What the active gradient in the filter paper that helps preserve must be clarified. It seems that the filter paper is only a good alternative sample collection method.