Thats not how nature works. Diseases typically become less deadly over time since introduction to a new host; strains that terminate their host are less viable

Thats not how nature works. Diseases typically become less deadly over time since introduction to a new host; strains that terminate their host are less viable than ones that keep a long lived infectious one. A mosquito that out competes other mosquitos while living a short hyperactive life is a better way to eliminate malaria by not giving it a necessary gestation period. Areas where a mosquito's life is short do not have malaria.