Differentiation of Coronavirus disease-19 (COVID-19) from methanol poisoning during the COVID-19 pandemic

Aims: Suspected blood stains are among common forms of trace evidence found at crime scenes. Therefore, discriminating between human and animal origin for blood stains is one of the fundamental analyses in forensic laboratories. Currently, tests for determining the origin of bloodstains, such as serology and presumptive tests, are timeconsuming and destructive to the sample. However, different polymerase chain reaction (PCR) methods can be used as highly sensitive and specific techniques for determining a bloodstain rsquo;s origin.Materials Methods: This experimental study was performed to evaluate conventional, nested, and multiplex PCR for discriminating between human and animal bloodstains, and using them in criminal investigations. These methods were designed based on the PCR amplification of cytochrome b and 16S ribosomal mitochondrial DNA fragment.Findings: The presence of a single band 157 and 170 base pair (bp) in nested and conventional PCR, respectively, as well as two bands 157 and 359 in multiplex PCR, indicates a human blood sample. However, the presence of a single band 359 bp in multiplex PCR and multiple bands in conventional PCR points to the sample rsquo;s nonhuman origin.Conclusion: This study demonstrated that a multiplex PCR assay designed based on the identification of mitochondrial ribosomal 16S gene has high accuracy in differentiating between human and nonhuman bloodstains, in addition to being affordable in terms of time and cost. This assay can be useful for forensic purposes because the 16S ribosomal mitochondrial fragment is a small humanspecific fragment that is easily amplifiable, even in degraded DNA samples from biological materials.