A concerning new study has revealed that the Andes strain of hantavirus—responsible for a severe, often fatal respiratory illness—can persist in human semen for up to six years after infection, raising potential concerns about sexual transmission. The research, conducted by Switzerland’s Spiez Laboratory (a government institute specializing in biological, chemical, and nuclear threat response), was published in the peer-reviewed journal Viruses.
A 55-Year-Old Swiss Man’s Case
Scientists tracked the case of a 55-year-old Swiss man who contracted the Andes hantavirus during travel to South America. Though standard tests later showed no detectable virus in his blood, urine, or respiratory tract, researchers identified viral genetic material in his semen as late as 71 months—nearly six years—after initial infection.
Testes as a Viral ‘Sanctuary’
The study highlights how the testes can act as an immunologically privileged site—a so-called ‘viral reservoir’—where pathogens may evade immune detection. This phenomenon is not unique to hantavirus; similar long-term persistence has been observed with other dangerous viruses, including Ebola and Zika.
Sexual Transmission Remains Theoretical—but Plausible
While no confirmed cases of sexual transmission have been documented to date, the authors state plainly: “Overall, our results indicate that the Andes virus has the potential for sexual transmission.” They explain that sperm cells are naturally shielded from immune surveillance—an evolutionary safeguard for reproduction—which inadvertently creates a protective niche where viruses may linger for extended periods.
Public Health Implications
The findings have prompted renewed attention, especially following recent outbreaks—including eight confirmed hantavirus cases aboard the cruise ship MV Hondius, and around 20 asymptomatic individuals placed in isolation in the UK. In response, Airfinity, a global public health risk monitoring firm, recommends that male hantavirus survivors receive detailed guidance on safe sexual practices well beyond the standard 42-day quarantine period. Their suggested approach mirrors WHO protocols for Ebola survivors, which include repeated semen testing and abstinence or condom use for up to several months—or longer—based on test results.