Chlamydia can cause irreversible damage. In women, infection can progress to pelvic inflammatory disease, or PID. This condition can cause permanent damage to the fallopian tubes and lead to infertility. PID also increases the chance that a woman will develop an ectopic pregnancy, whereby a fertilized egg is implanted, not in the womb, but in a fallopian tube. This can cause the tube to rupture, potentially resulting in death. An infected woman can also pass the bacterium on to her baby. This can lead to potentially fatal Chlamydial pneumonia or to potentially blinding neonatal conjunctivitis. Women who have Chlamydia are also 5 times more likely to contract HIV, the virus that causes AIDS, if exposed to it. Men do not usually experience any effects of Chlamydia. However, the disease CAN spread to the testicles, possibly resulting in infertility. On rare occasions, untreated Chlamydia can cause reactive arthritis, a disease that may lead to permanent disability.