At a first consideration, one might argue that it depends on the disease and on the circumstances and there seems to be no single answer. However, if one looks further between the lines then an answer for the worst pathogen seems to appear.
Viruses, bacteria, and parasites can kill, mame and disfigure. Yes.
But now consider WHERE most of the deaths and misery occur and WHY the misery occurs and why the people can't get access to cures.
Could the worst pathogen of all be the greedy human? For example, humans that channel aid into money for arms or personal posessions. Humans that charge extortionate rents and cause misery for tennants and their families through poverty. Some might argue for the inclusion of internet gambling companies and loan sharks into this list. Greed that forces the poor into prostitution. Humans that oppose health care for the poor because "I'm all right jake". The human that will own several jets and yachts whilst the sweat shop workers starve or have to rake in rubbish dumps to find some scrappings of half rotted chicken left overs for their kids.
So perhaps it's not MRSA, AIDS or FLU or even rabies, but human greed, that is the worst pathogen of all.
Perhaps it kills more than all the diseases combined ?
(Scientist)
It is a non-specific Immune response as it does not change based on interaction with a pathogen and will activate regardless whether the pathogen in question has been encountered previously. Commonly referred to as being part of the "Second Line of Defence".
Bacteria
Ebola virus is a pathogen that causes diseases of the circulatory system. This can cause failure of most organs and serious bleeding or hemorrhaging.
Sometimes bacteria is the pathogen involved.
Tetanus is caused by a bacterium, Clostridium tetani, so the pathogen type is bacterial.
It's known as "Hydro Prethecitics" most common in the female body.
pathogen
virus
A pathogen causes infectious disease. For instance, influenza virus is the pathogen that causes flu.
A Virus IS a type of Pathogen.
Viruses
Memory cells are a type of immune cell that "remember" an encounter with a specific pathogen. When the same pathogen is encountered again, memory cells mount a faster and more robust immune response, helping to quickly eliminate the pathogen before it can cause a full-blown illness. This quicker and more effective response is what helps prevent a person from getting sick upon subsequent encounters with the same pathogen.