Re-evaluating the unknown causes of male infertility: Amebiasis as an emerging etiology.

Infertility remains a multifactorial medical challenge, particularly when its etiology is obscure. This study investigated whether Entamoeba histolytica (E. histolytica), the causative agent of amebiasis known for its invasive and cytolytic potential, could be associated with male infertility through potential targeting of reproductive tissues. Twenty-four adult male rats were equally divided into control and infected groups. Following infection, mating trials were conducted to assess fertility outcomes. Testicular and epididymal tissues were collected for PCR-based parasite detection, histological examination, sperm analysis (count, motility, morphology), and serum hormonal assessment, including testosterone (T), follicle-stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL), and estradiol (E2). PCR detected E. histolytica DNA in the testes and epididymis of infected males, suggesting possible tissue invasion. Histopathological examination revealed extensive degeneration of seminiferous tubules and depletion of spermatogenic cells. Correspondingly, infected males showed severe spermatogenic failure, with drastically reduced sperm count (1.46 ± 0.13 vs. 46.90 ± 1.00 × 106/mL, P < 0.05), elevated immotile sperm (98.08 ± 0.51 % vs. 25.08 ± 0.51 %), and increased morphological abnormalities (76.33 ± 1.01 % vs. 13.00 ± 0.68 %). Endocrine disruption was also evident, with decreased T (0.250 ± 0.029 vs. 0.727 ± 0.039 ng/mL) and FSH (0.456 ± 0.009 vs. 0.724 ± 0.024 mIU/mL), alongside elevated PRL (0.442 ± 0.007 vs. 0.219 ± 0.013 ng/mL) and E2 (621.0 ± 32.04 vs. 405.5 ± 12.48 pg/mL) (P < 0.05); LH levels remained unchanged (P = 0.260). Importantly, infected males exhibited complete fertility failure (0 % pregnancy rate). Collectively, these findings suggest a potential link between E. histolytica infection and impaired male reproductive function. The consistent pattern of pathological, spermatogenic, and endocrine alterations provides preliminary evidence for further investigation into this association, though additional studies are needed to confirm causality and clinical relevance.