There is not one "most harmful disease". In fact, there are lists of "harmful" diseases that can kill anyone at any time (example: kidney disease, Heart disease), or can take years to kill.
Ignorance
the most harmful disease in the world is cancer (it kills the most people).
they carry disease that can be harmful
Most of the bacterial species are NOT harmful. Few are harmful. If they happen to be harmful then they will harm you with out regard to shape. Whether oval, long or spiral.
It kills you...
A contagion is either a disease spread by contact, the spread of such a disease, or the spread of anything harmful, as if it were a disease.
There has been no harmful disease noted about this.
Starvation, disease, death.
Both.
it is harmful because the Plasmodium is carrying a malaria disease then it can get to a mosquito to humanss
Assuming your partner is disease free, then no.
harmful mutation