Researchers from different institutions in Europe have mapped 22 viruses capable of persisting in semen after acute infection, potentially contributing to the transmission of the disease or even the emergence of an outbreak, as some of them have pandemic potential. The findings were published in an article in The Lancet Microbe.
“There are cases in which, after a virus, such as Zika, it was found that the form of transmission was sexual”, reports infectious disease specialist Emy Akiyama Gouveia, from Einstein Hospital Israelita. “However, it is important to differentiate the viruses evaluated from sexually transmitted infectious diseases themselves, such as HIV and syphilis.” In addition to these, the presence of viruses in semen in cases of chronic infections is well established for hepatitis B and C, cytomegalovirus, among others.
For the study, the authors reviewed another 373 scientific works. They assessed both the presence of the virus in male fluid and the number of days that the pathogens remained viable after the onset of the disease.
Of the 22 viruses mapped, only nine already had any evidence of . Some examples are Ebola, hepatitis E, mpox, dengue, zika and marburg virus. In the case of mpox, for example, the sexual route was a key factor in the global spread of the disease in the 2022 and 2024 outbreaks. Other agents, such as Sars-Cov-2 (which causes Covid-19), yellow fever, adenovirus and chikungunya, have not yet been associated with this route of transmission.
Ebola was the longest-lasting virus in semen, detected 988 days after the patient was discharged from hospital. The others stayed for much less time: the dengue one stayed for about a month; o, two months; and Covid-19, almost three months (81 days). The virus with the shortest duration after the start of infection, just eight days, was the one that caused Kyasanur forest disease, an endemic infection in southeastern India that can lead to hemorrhages.
According to the authors, the mere presence or ability to replicate in cell culture does not mean that these pathogens are sexually transmitted, as this depends on other factors, such as viral load, immune system and the ability of the virus to infect cells in the reproductive tract. Furthermore, the great persistence of the virus could be due to the impairment of the individual’s immune system.
But knowing which microorganisms can resist in semen allows doctors and public health authorities to implement strategies and guidelines to stop possible transmission, including education and recommending the use of condoms, for example.
“After these infections, the patient would have to be instructed to use condoms for a variable period of time, depending on the disease. But sometimes this potential for transmission is unknown and, therefore, people end up forgetting to provide such care”, observes the infectious disease specialist.
However, the authors recognize that the study has limitations, such as the heterogeneity of the types of research evaluated and the great variability of results.
