Table 1 Major viruses infecting men and their consequences on male fertility

Hepatitis B virus

• Seminal fluid and spermatozoa [7,8,9]

• Testis [10, 11]

• Testicular pain [12]

• Testicular vasculitis and thrombosis [12]

• Scrotal swelling and pain [13, 14]

• Epididymitis [13, 14]

• Lower sperm quality [15,16,17,18,19,20]

Herpes Simplex virus

• Penis [21, 22]

• Urethra [21, 23]

• Testis [24]

• Expressed prostatic secretions [25]

• Prostate tumour tissue [26]

• Seminal vesicles and semen [4, 24, 27,28,29]

• Spermatozoa [30]

• Urethritis and urethral discharge [21, 23, 31]

• Epididymo-orchitis [32]

• Penile vesicles and lesions [21,22,23]

• Local pain and itching [23]

• Dysuria [21, 23]

• Chronic prostatitis [25]

• Controversial association with prostate cancer [26, 33, 34]

• Controversial effects on sperm parameters [4, 27,28,29,30] however:

• Possible impaired prostatic and epididymal functions [4]

Human Immunodeficiency Virus

• Penis [35,36,37]

• Urethra [36, 37]

• Prostate [38, 39]

• Seminal vesicles and semen [40, 41]

• Testis [38, 39, 42]

• Epididymis [39]

• Erosion of seminiferous tubule epithelium [39]

• Necrosis of seminiferous tubule walls [39]

• Testicular interstitial fibrosis [43]

• Thickening of seminiferous tubule basement membranes [43]

• Epididymal obstruction [39, 43]

• Testicular cancer [44]

• Impaired spermatogenesis [39, 43]

• Azoospermia [39]

• Lower sperm counts and ejaculate volumes [45, 46]

• Fewer progressively motile sperm [45,46,47]

• Alteration of sperm morphology [46]

Human Papillomavirus

• Penis [48]

• Urethra [48, 49]

• Testis [50]

• Epididymis [51]

• Vas deferens [52]

• Prostate [53, 54]

• Semen [48, 52, 55,56,57]

• Penile cancer [49]

• Prostate cancer, controversial [58, 59]

• Prostate disturbances [55]

• Lower chances of pregnancies [60,61,62]

• Higher risks of miscarriage [55, 60, 61]

• Low sperm morphology score [60, 61]

• Increased sperm DNA fragmentation index [61]

• Decreased sperm progressive motility, controversial [55,56,57, 60, 61]

Mumps virus

• Testis [63]

• Semen [64]

• Scrotal swelling and pain [65, 66]

• Hydrocele [65]

• Epididymo-orchitis [65]

• Orchitis [63, 64, 66,67,68]

• Testicular atrophy [66,67,68]

• Decreased serum testosterone level [66, 67]

• Impotency [67]

• Decreased sperm count and motility [64, 69]

• Altered sperm morphology [64, 69]

• Oligozoospermia and azoospermia [64, 66, 68, 69]

• Hypofertility or infertility?

SARS-CoV-2

• Testis [70, 71]

• Semen [72,73,74,75,76]

• Decreased testis volume [77]

• Orchitis [71, 78]

• Degeneration/loss of germ cells and spermatocytes [71, 78, 79]

• Sertoli cells alteration [78]

• Thickening of seminiferous tubule basement membranes [78, 80]

• Increased apoptotic testicular cells [71, 79]

• Testicular microthrombosis [78]

• Epididymitis [81, 82]

• Scrotal and testicular pain [82]

• Possible prostatic infarction and acute urinary retention [83]

• Not directly reported however:

• Impaired spermatogenesis and oligozoospermia [71, 78, 79]

• Decreased total testosterone level [77, 84,85,86]

• Decreased seminal volume, sperm count, sperm concentration and total sperm motility [77, 79, 86]