Miasma is an evil plague dragon that only desires to spread his infection throughout the land. When infected you will begin to cough violently, eventually coughing blood as your lungs begin to fail. You will feel weak and tired. Eventually you will begin to hear Miasma as he speaks to you through the plague. Your body will undergo a change and you will turn into a Plague Wretch.
Also if you noticed YES he DOES have genitallia but HE is not erect so. yeah. not this picture but maybe a different one.