The Nipah Virus causes severe illness. A person with this infection will get a respiratory disease, a term that includes extreme conditions affecting the organs and tissues that make gaseous exchange possible in organisms, and includes conditions of the upper respiratory tract, trachea, bronchi, alveoli, pleura and the nerves and muscles of breathing. (Source c)
Respiratory diseases would range from mild infections to very self-limiting infections. (Source g) Examples would be the common cold, to life-threatening entities like bacterial pneumonia, severe asthma and lung cancer.
Another cause would be encephalitis which is inflammation of the brain, caused by infection or an allergic reaction. If the case is very bad