What Causes Water Or Infection In The Brain?

My cousin 45 years old was diagnosed to have typhoid fever,after 2 weeks of having sypmtoms of headaches,vomitting,itc.she just had a brain surgery to drain the water or infection from the brain,and it just got worsed,now she has a respiratory oxygen to prolong her breathing..doctors said she only have 10% survival rate..in short she's dying now..why too fast?did the brain surgery just got it worst?is it really needed?