I. What diseases affect fertility? There are many diseases that may affect the occurrence and quality of spermatozoa, thus causing infertility, and in severe cases may lead to irreversible changes. 1. Fever A fever of more than 38.5°C may inhibit spermatogenesis for up to 6 months (World Health Organization, 1987). Recent data show that fever can also cause damage to sperm DNA. 2. Oncological treatment Young people may suffer from testicular cancer, lymphoma and leukemia, and these diseases and their associated treatments (chemotherapy and radiotherapy) may seriously affect fertility. For these cases, semen freezing should be performed prior to treatment. Any surgery, especially surgery with general anesthesia, may temporarily inhibit fertility for up to 3-6 months; testicular biopsy may lead to short-term suppression of spermatogenesis; urethral valve surgery in early childhood, prostatectomy, bladder neck surgery for urinary obstruction may lead to retrograde ejaculation; inguinal hernia surgery may damage the vas deferens; vasectomy may lead to obstructive azoospermia and the production of anti sperm antibodies. 4, genitourinary tract infections and STDs Some serious lower urinary tract infections, prostatitis, vesiculitis may cause a decrease in sperm quality and semen volume; gonorrhea, non-gonococcal urethritis and mycoplasma, chlamydia infection or other microbial infections that are not completely cured become chronic or recurrent may cause urethral stricture, inflammation of the vas deferens or epididymis, and lead to blockage of the vas deferens tract, causing azoospermia. Second, how much does prostatitis affect fertility? The prostate fluid is a component of semen, and the prostate fluid contains liquefaction factors that can liquefy semen. The actual amount of impact cannot be precisely determined, therefore, patients with definite prostatitis need to be treated, while infertile patients without obvious prostatitis symptoms have no clear effect by treating prostatitis to improve sperm quality.