A new study has documented what researchers say is the first confirmed evidence that Marburg virus can be sexually transmitted after a patient has recovered from the disease, prompting calls for changes to survivor follow-up and public health guidelines.
Published in Nature Health, the study investigated two women who developed Marburg virus disease during Rwanda’s 2024 outbreak despite having no known exposure to infected patients or treatment centres.
The only link investigators could identify was that both women had recently had unprotected sex with men who had recovered from Marburg virus disease and had already been discharged from hospital after testing negative for the virus in their blood.
Researchers later detected Marburg virus RNA in the men’s semen, even though the virus was no longer detectable in their blood.
“The reported sexual contact between the cases, supported by the detection of Marburg RNA in semen and consistent epidemiological evidence, strongly suggests sexual transmission as the most likely route of infection,” the researchers wrote.
Until now, scientists had suspected that sexual transmission of Marburg might be possible because the closely related Ebola virus can persist in semen after recovery. However, the authors note that “confirmed sexual transmission of Marburg virus has not been previously reported.”
The study describes two separate case pairs.
In the first, a 25-year-old man recovered from Marburg after spending 13 days in hospital and was discharged after two consecutive negative blood tests. Nine days later, he had unprotected sex with his 21-year-old partner, who developed symptoms five days later and subsequently tested positive for Marburg virus disease.
In the second case, a 29-year-old male survivor was discharged after two negative blood tests. Four days after having unprotected sex with his partner, she became ill and was later diagnosed with Marburg.
Investigators carried out detailed contact tracing but found no other likely source of infection for either woman.
According to the study, “Post-discharge testing revealed persistent viral detection in semen, while all other specimens were negative, making alternative routes of transmission highly unlikely.”
The findings suggest that although patients may no longer have detectable virus in their blood and appear clinically recovered, viral genetic material can remain in semen for some time after discharge.
The researchers caution that the study does not suggest sexual transmission is a common route of Marburg spread. The virus continues to spread primarily through direct contact with the blood or other body fluids of infected people during acute illness.
However, they say the findings have important implications for survivor care.
Following the outbreak, Rwanda introduced mandatory semen testing after discharge, structured education programmes for survivors and their families, and long-term follow-up of recovered patients to monitor viral persistence.
The researchers say these measures could help reduce the risk of future transmission while improving understanding of how long the virus can persist in survivors.
“These findings underscore the need to revisit and potentially revise the current guidelines and indications for recovery programmes,” the authors wrote.
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