Hantavirus may remain in human semen for up to six years and could potentially be transmitted sexually, according to a peer-reviewed study that examined a long-term patient case.
Scientists from Switzerland’s Spiez Laboratory, an institution focused on biological threats, followed a 55-year-old man who contracted hantavirus in South America. While the virus was no longer present in his blood, urine, or respiratory tract as he recovered, researchers detected viral genetic material in his semen 71 months (five years and 11 months) after infection. This finding is detailed in a 2023 paper.
These results suggest that the virus might be passed on years after the initial infection. “Taken together, our results show [the virus] has the potential for sexual transmission,” the research team stated.
Hantavirus typically spreads to humans through contact with rodents. In rare cases, it can lead to hantavirus cardiopulmonary syndrome, a severe illness with a fatality rate of 25–40 per cent. According to the World Health Organisation (WHO), this makes it a disease of major public health concern.
Symptoms can progress quickly from fever and nausea to life-threatening complications involving the lungs and heart. Since the discovery of the disease on the MV Hondius cruise ship, a total of 11 cases have been reported, including three deaths.
The outbreak occurred during a cruise from Argentina to the Antarctic and then to several isolated islands in the South Atlantic Ocean. The 2023 study suggests that the male reproductive tract may act as a “reservoir” where the virus can avoid the immune system—a pattern also observed in viruses like Ebola and Zika.
This research has already led some experts to recommend that the WHO revise its guidelines. Currently, the organisation advises that “as a precautionary principle, WHO recommends active monitoring and home or facility quarantine of high-risk contacts for 42 days following last exposure.”
Airfinity, a company that tracks global health risks, has suggested that male patients should receive “extensive safe-sex guidance beyond the [42-day] quarantine.” The guidance should be “analogous to the World Health Organisation’s Ebola survivor semen-monitoring protocols,” a spokesperson told The Telegraph. They added that until tests confirm they are clear of the virus, individuals should “use condoms” and wash themselves “thoroughly” after any contact with semen.
The WHO protocols state that the semen of male survivors of Ebola should be tested every three months and not be considered clear before two consecutive negative test results.
Researchers found only minimal genetic changes in the virus over the six-year period, indicating very slow or limited replication. The study does not confirm how frequently sexual transmission occurs, but the evidence shows it is biologically plausible and warrants further investigation.
A spokesperson for the UK Health Security Agency (UKHSA), which is monitoring British passengers from the MV Hondius, told The Independent: “There are currently no confirmed cases of Hantavirus in England. UKHSA keeps all guidance under constant review and monitors emerging evidence, including international research, as it becomes available. Any individuals in England who are confirmed as cases or identified as contacts will be provided with all necessary public health advice, including on reducing the risk of onward transmission.”
They added: “We continue to work closely with international partners, including monitoring guidance issued by other national health agencies, to ensure our advice reflects the best available evidence.”
