Infertility poses a significant challenge for approximately one-sixth of couples worldwide, with male infertility rates steadily rising. Yet, the precise implications of viral infections on fertility have remained poorly understood. This comprehensive review synthesizes findings from numerous studies, cataloging 40 viruses detected in human semen. It outlines their characteristics, modes of transmission, and effects on both the reproductive and endocrine systems. The review also delves into potential pathogenic mechanisms and treatment avenues for viruses strongly associated with male infertility. This analysis aims to deepen our understanding of how viral infections influence male reproductive health, providing critical insights for future research and the diagnosis and treatment of infectious infertility.
The World Health Organization defines infertility as the inability to achieve pregnancy after at least 12 months of regular unprotected intercourse. Globally, an estimated 17% of couples are affected by infertility, with male factors contributing to half of all cases. Recent data indicate a notable increase in male infertility cases worldwide, with prevalence reaching approximately 56 million in 2019, marking a significant rise since 1990.
Various factors contribute to male infertility, including congenital, acquired, or idiopathic conditions that affect sperm production. Reproductive tract infections, in particular, play a pivotal role, with studies showing a high prevalence of genitourinary tract infections among infertile men. Notably, a substantial proportion of primary infertile men exhibit asymptomatic semen infections, which can lead to abnormalities in sperm concentration.
Research has identified 40 viruses present in the male reproductive tract and semen, many of which display a strong affinity for the testes. Concerns have also surfaced during the COVID-19 pandemic, suggesting that SARS-CoV-2 may adversely impact male fertility. Viruses within semen can infect sperm or precursor cells, potentially leading to reproductive system pathologies, semen parameter abnormalities, and decreased sperm quality. Furthermore, such infections may pose risks of virus-induced mutations transmitted to future generations.
Despite advancements, establishing a definitive correlation between viral infections and fertility remains challenging. This review aims to consolidate key findings on viruses in human semen, highlighting their diversity, identifying viral species linked to male infertility, and discussing avenues for further clinical research with implications for fertility management.
A systematic search across PubMed, Embase, and Web of Science identified 40 viruses present in human semen, each with varying degrees of evidence regarding sexual transmission. Chronic or latent infections, such as herpes viruses and HIV, coexist with viruses causing acute infections like Zika virus, Ebola virus, and chikungunya virus. Of these, only Zika virus and Ebola virus have been extensively studied beyond isolated case reports. Table 1 summarizes the main characteristics and clinical implications of these viruses for male fertility.
In summary, this review underscores the complex interplay between viral infections and male fertility, emphasizing the need for further research to elucidate their impact and potential therapeutic strategies.
Related Links:
