Diseases very often modify the behavior of the host to help them spread. They don't do it "intelligently" they do it on accident by hitting on a modification of the host which results in better transmission of the disease.

Covid makes you cough to spread little droplets filled with virii, rabies makes mammals violent so they'll bite to spread infection through saliva. It isn't through intense manipulation, it's by pulling a few levers. One species taking advantage of another species through biochemistry is extremely common. Every psychoactive drug, poison, etc. are all manipulations through chemistry.