Published in The FEBS Journal, the research demonstrated that this parasite is capable of infecting and multiplying within the testes and the epididymis—a coiled tube attached to each testis that stores and transports sperm—causing cellular damage, inflammation, and structural alterations in these tissues.
For decades, toxoplasmosis has been known to pose particular risks for women during pregnancy, as it can lead to miscarriage or congenital malformations. This is why prenatal checkups often include a blood test to detect the parasite. However, until now, very little was known about its potential impact on male fertility.
The recent study—led by María Eugenia Francia and Leandro Tana from the institute’s Apicomplexa Laboratory—found that once T. gondii infects the body, it interacts directly with human sperm cells, causing morphological alterations such as loss of the head, twisted tails (which impair motility), and damage to the cell membrane.
The researchers also confirmed that the parasite disrupts mitochondrial function in sperm—structures essential for energy production—which could compromise their viability. In addition, the presence of the parasite in the testes and epididymis suggests that it may interfere with key stages of sperm development (spermiogenesis), not only damaging already mature cells.
Because toxoplasmosis is a very common infection in humans, these findings suggest it may be an underdiagnosed factor in certain cases of male infertility. The authors stress the need for further research to assess its clinical impact and to consider parasitic infections in the fields of andrology and reproductive medicine.
The study also raises questions about a possible sexual transmission route for the parasite, which remains largely unexplored, as T. gondii has been detected in human semen and in the sexual organs of infected animals. This opens a new line of research into male reproductive health and reinforces the importance of including parasitic infection screening in fertility assessments.
