Male fertility has been declining over the past half century. A 1992 analysis noted that there has been a steady decline in sperm count and quality since the 1940s. A recent study found that from 1990 to 2019, the male infertility rate was nearly 80%. What drives this trend remains a mystery, but often cited culprits include obesity, poor diet and environmental toxins.
Infectious diseases such as gonorrhea or chlamydia are usually factors that affect male fertility. Accumulated evidence suggests a common single-cell parasite called Toxoplasma gondii Toxoplasma gondii Perhaps a contributor: An April 2025 study showed that when in direct contact with the parasite, “human sperm loses its head.”
I am a microbiologist, my lab study Toxoplasma gonzo. The new study enhances emerging findings and emphasizes the importance of preventing this parasitic infection.
There are many ways you can get toxoplasmosis
Infected cat defecation Toxoplasma gonzo Eggs enter bins, gardens, or elsewhere else and can be picked up by humans or other animals. Water, shellfish, unwashed fruits and vegetables can also hide infectious parasite eggs. In addition to eggs, toxoplasmosis can also be transmitted if tissue cysts in poisonous animal meat are not destroyed by cooking to the appropriate temperature.
Although most parasite hosts can control initial infection, there are few symptoms, Toxoplasma gonzo As dormant cysts in the brain, heart, and muscle tissue, remain in the body. These cysts can reactivate and cause attacks of other serious diseases, thus destroying critical organ systems. Between 30 and 50% of the world’s population is permanently infected Toxoplasma gonzo Due to the many ways parasites can spread.
Toxoplasma gonzo Can target male genital organs
After infection, Toxoplasma gonzo Spread to almost every organ and skeletal muscle. evidence Toxoplasma gonzo It can also target the male reproductive organs that first emerged during the AIDS pandemic in the 1980s, when some patients developed parasitic infections in their testicles.
While immunocompromised patients are most likely to develop toxoplasmosis testicularly, it can also occur in other healthy individuals. Imaging studies of infected mice confirm Toxoplasma gonzo The parasite quickly travels to the testicles and eyes within a few days after infection.
DPDX Image Library/CDC
In 2017, my colleagues and I discovered Toxoplasma gonzo Cysts can also be formed in the mouse prostate. The researchers also observed that these parasites, including human semen, in ejaculation in many animals, increased the possibility of sexual transmission.
Know this Toxoplasma gonzo It can reside in male reproductive organs, which has prompted an analysis of the fertility of infected men. A small 2021 study of 163 men infected with Prague Toxoplasma gonzo More than 86% of people were found to suffer from semen abnormalities.
A 2002 study in China found that infertile couples are more likely to have Toxoplasma gonzo Infection with couples with fertile infections was 34.83% compared to 12.11%. A 2005 study in China also found that sterile men are more likely to test positive Toxoplasma gonzo A man who is more fertile. However, not all studies have created a link between toxoplasmosis and sperm mass.
Toxoplasma gonzo It will directly harm human sperm
Toxoplasmosis in animals reflects infections in humans, which allows researchers to solve problems that are not easy for people to check. Testicular function and sperm production have decreased significantly Toxoplasma gonzo– Infected mice, rats and rams. The sperm count in infected mice was significantly reduced, and the proportion of sperm with abnormal shape was higher.
In the April 2025 study, researchers from Germany, Uruguay and Chile observed Toxoplasma gonzo The testicles and epididymis can reach the tubes where sperm matures and stores two days after the mouse is infected. The discovery prompted the team to test what happens when the parasite comes into contact with human sperm in a test tube.
Five minutes after exposure to the parasite, 22.4% of sperm cells were beheaded. The longer it interacts with the parasite, the number of decapitated sperm increases. The sperm that keeps the head is often twisted and deformed. Some sperm cells have pores on the head, indicating that the parasite is trying to invade them because it penetrates into any other type of cells in the organ. In addition to contacting directly, Toxoplasma gonzo Since infection promotes chronic inflammation, it may damage sperm. Inflammatory conditions in the male reproductive tract are harmful to the production and function of sperm.
Researchers speculate on harmful effects Toxoplasma gonzo Over the past few decades, it could lead to a significant global decline in male fertility.
Rojas-Barón et al./FEBS Journal, CC BY-SA
Prevent toxoplasmosis
evidence Toxoplasma gonzo Whether male reproductive organs in animals can be convincing, but whether this can lead to health problems is unclear. Toxoplasmosis of the testicles suggests that parasites can invade human testicles, but symptomatic diseases are very rare. To date, studies showing sperm defects in infected men are too small to conclude at present.
Furthermore, some reports show that the incidence of toxoplasmosis in high-income countries has not increased over the past few decades, while male infertility has been rising, so it is likely to be just part of the puzzle.
Regardless of the potential impact of this parasite on fertility Toxoplasma gonzo. If someone gets an infection for the first time during pregnancy, it can lead to miscarriage or birth defects, which can be life-threatening for people with low immune function. Toxoplasma gonzo It is also the main cause of foodborne death in the United States.
Take care of proper cats, clean the bin immediately and in Toxoplasma gonzo. You can also protect yourself from this parasite by washing fruits and vegetables, cooking meat at the right temperature before consuming and avoiding raw shellfish, raw water and raw milk.
Bill Sullivan, professor of microbiology and immunology at Indiana University. This article is republished from the conversation under the Creative Sharing License. Read the original article.
