First, mosquitoes feed on living. They must have a blood meal for reproduction, so a dead body in which the blood has coagulated is not what they feed on.
There will be mosquito-born infectuous agents, West Nile being the most likely, but others also.
I don't bring these things up to address anything other that my concern that Nagan is either not getting good information from infectuous diseases experts, or he is getting the information confused. Nagan is not an entomologist nor a physician, but he should be more careful promulgating these types of ideas to the general public. It will exaccerbate the anxiety in the populus.
He's babbling, like he has done since he realized that only a complete coverup/diversion will save his ass. He can't lead, he won't follow, and he doesn't know when to shut up.
FWIW, I think by now most of the affected populus sees Nagin as a jester, not as an authority.