TEHRAN, July 3 -- Mohammad Mehdipour had been coughing for three months before a doctor at Evin Prison told him the diagnosis: tuberculosis. He is a political prisoner. He was not told how many other inmates had been exposed.

The case was reported July 2 by Radio Farda, the Persian-language service of Radio Free Europe/Radio Liberty, citing a source with direct knowledge of conditions inside the facility. The number of inmates who may have been in contact with Mehdipour, or how long the infection went undetected, has not been disclosed by Iranian prison authorities.

A prison is a closed system. Disease that enters it has nowhere to go. What has happened at Evin over the past thirteen months - a clinic destroyed by an airstrike, doors we...