Hantavirus may persist in human semen for up to six years and has the potential to be sexually transmitted, according to a peer‑reviewed study of a long‑term patient case.
Scientists at Switzerland’s Spiez Laboratory, a government institute specialising in biological threats, tracked a 55‑year‑old man who became infected with hantavirus in South America.
Although the virus disappeared from his blood, urine and respiratory tract as he recovered, researchers found detectable viral genetic material in his semen 71 months (five years and 11 months) after infection, according to the 2023 paper.
This suggests the virus could potentially be passed on years after somebody was initially infected.
“Taken together, our results show [the virus] has the potential for sexual transmission,” the research team said.
Hantavirus normally spreads to humans through rodent exposure, and in rare cases can cause hantavirus cardiopulmonary syndrome, a severe illness with a fatality rate of 25 – 40 per cent, which according to the World Health Organisation (WHO) makes “a disease of major public health concern”.
Symptoms can escalate rapidly from fever and nausea to life‑threatening lung and heart complications. A total of 11 cases, including three deaths, have been reported since the discovery of the disease on the MV Hondius cruise ship.
The ship was on a cruise from Argentina to the Antarctic and then to several isolated islands in the South Atlantic Ocean when the outbreak was identified.
The 2023 study suggests the male reproductive tract may act as a “reservoir” where the virus can evade the immune system – a pattern also seen in viruses including Ebola and Zika.
The research has already prompted some experts to suggest the World Health Organisation should revise its guidance.
In its current advice, the organisation has stated 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 which tracks global health risks, 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, adding that until tests show them to be clear of the virus, they should “use condoms” and wash themselves “thoroughly” after any contact with semen.
The WHO protocols say 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 often sexual transmission occurs, but researchers say 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.”