Have extraterrestrials brought or engineered deadly pathogens to use against humanity? What are examples? Did this include the plague or malaria?

This is quite true. So the diseases that are conveyed by the tick and the mosquito are typically ones introduced by the extraterrestrials to take advantage of those vectors they themselves introduced, to worsen the consequences, and to be a major problem for humanity. It is how they think. If they can find a new way to torture humans, they will do it with relish. This is as good an illustration as any of their depravity. So the blood-borne diseases such as malaria in particular, are transferred here to be a part of the human biosphere. And if you think about the complicated lifecycle involved with malaria transmission, you can see that it only can come about with the entire system available, including the vector, to inject it into the bloodstream of a host. This entire system was a creation, but it was a creation done as a parallel and consequence to the degraded status of the Reptilian. And so it belongs to their world and is in keeping with the kinds of energies it has, but does not belong on earth, the land of divine human. That is an incursion and a degradation courtesy of the extraterrestrial interlopers themselves.