Answer: Brain
Explanation:
There are many sexually transmitted disease which is caused due to bacteria. Even if it is curable it may causes serious in various parts of the body.
The bacteria might travel to the brain and cause severe problems. The bacteria is so infectious that it can even damage the other parts of the body such as nervous system and other parts.
In more severe conditions the STIs can lead to the death of the person but this happens in severe cases where the diseases is not treated with medicines.
