Critical Reasoning

"Epidemiologist: Malaria passes into the human population when a mosquito carrying the malaria protozoa bites a human who has no immunity. The malaria parasite can remain for up to forty days in the blood of an infected person. The disease cannot be passed from person to person, unless a non-infected person is exposed to the blood of an infected person. Theoretically, malaria could be eradicated in any given area, if all the mosquitoes carrying malaria in that area are exterminated. If such a course of action is carried out at a worldwide level, then the global eradication of malaria is possible."

Source: Magoosh

Question/comment: Please look at the bold part. Isn't this weird? Isn't weakening of argument present in the argument itself? If transfer through blood is possible then of course existence and spread of malaria is to happen whether or not we kill all the mosquitoes.