A strange and unusual condition, telepathitis is transmitted by mental contact with an infected creature, or more rarely through physical contact with brain tissue. Such contact requires a DC 13 Constitution save if physical contact is made, or a DC 11 Wisdom save if mental contact is made. Failure results in infection.

A creature so infected can begin to read thoughts, but does so erratically, gleaning surface thoughts from any nearby creatures. Through mental strain, an infected creature can hone the ability and listen to specific thoughts, as per the spell detect thoughts. They can only use this ability once and regain the ability to do so after each long rest.

However, this and other mental stressors cause the disease to worsen, and they begin to deteriorate. An infected victim gains an exhaustion level each time they strain to use their ability to detect thoughts and gain an additional exhaustion level if they read the thoughts of a creature with an intelligence score of 18 or higher.

The infected creature also gains a level of exhaustion if they are around a crowd of 10 or more for more than a minute. With each level of exhaustion gained, the infected suffers from a headache of increasing intensity.

When the infected creature reaches 6 levels of exhaustion, their head explodes and they die. This can only be prevented by prolonged sensory deprivation and rest. The infected creature cannot have any levels of exhaustion nor be exposed to any thoughts for a minimum of 3 days. If such conditions are met, they are no longer infected.

Curiously, creatures that resemble brains are susceptible to this disease, which displays more as a wasting cancerous condition. Intellect devourers, grell, and brain consuming creatures are likely vectors for this disease, which sometimes mercifully thins their populations.