I would think there would be 2 factors: 1/ condition of the immune system & support and 2/ type of organism.
Given that the immune system is supported through nutritionals, it can sustain the infection. The body uses lots of resources when fighting these infections. There are a number of spices/herbs that can at least control the infection.
Controlling the stress created by these infections is important. This means understanding what you can and cannot do will help, managing the social/family constraints etc. Stress accelerates degradation of the immune system.