While natural vectors respect species barriers, the barrage of artificial vectors made by genetic engineers are designed to cross species barriers, thus greatly enhancing the potential for creating new viral and bacterial pathogens, and spreading drug and antibiotic resistance. Totally unrelated pathogens are now showing up with identical virulence and antibiotic resistance genes.
Recent statistics are frightening.
Multi-drug resistant tuberculosis is now estimated to affect 10 million each year with 3 million deaths. At least 50 new viruses attacking humans emerged between 1988 and 1996. The first genetic engineers called for a moratorium in the Asilomar Declaration of 1975, precisely because they were afraid of inadvertently creating new viral and bacterial pathogens. The worst case scenario they envisaged may be taking shape. Commercial pressures led to regulatory guidelines based largely on untested assumptions, all of which have been invalidated by recent scientific findings.