Ebola Resource Center

Ebola Resource Center

May 16, 2016
2 min read

Persistence of Ebola virus in semen raises concerns over resurgence

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Despite evidence of long-term viral clearance, Ebola virus RNA may persist in the semen of some male survivors for as long as 9 months, according to recently published findings.

As these data do not describe long-term semen infectivity, health officials should continue to promote safe sex practices among Ebola survivors to reduce the risk for flare-ups, according to Mamadou S. Sow, MD, of the infectious diseases department at Donka University National Hospital, Guinea, and colleagues wrote.

Viral RNA detected 276 days after illness onset

In March 2015, Sow and colleagues began enrolling Guinean Ebola survivors into a follow-up cohort intended to monitor the patients for up to 1 year after discharge. Along with regular clinical, psychological and social assessments, the researchers collected semen specimens for Ebola virus RNA detection by reverse transcription PCR.

As of Oct. 29, 2015, the researchers had collected and analyzed 98 semen specimens from 68 Ebola survivors. They reported positive PCR results in 10 samples collected from eight men up to approximately 9 months after onset of the disease. More specifically, four positive specimens were obtained 1 to 3 months after onset, three were obtained after 4 to 6 months, two after 7 to 9 months, and one after 276 days.

The proportion of tested positive specimens and the viral RNA load decreased over time, the researchers wrote — evidence of long-term viral clearance. These findings corroborate other reports of persistent seminal genetic material seen in recent survivors in Sierra Leone and Liberia, as well as early reports of seminal fluid specimens containing viral RNA following a 1995 outbreak in the Democratic Republic of the Congo. However, viral isolation and sequencing are still needed to determine the semen’s infectivity, Sow and colleagues wrote.

“Our report adds further evidence of long-term persistence of viral RNA for up to 9 months among survivors, with the same decreasing trend over time,” they wrote. “In the absence of evidence on noninfectivity, these preliminary results from Guinea, as well as findings from the Liberian case and the Sierra Leone report, should reinforce the importance of safe sex practices among Ebola survivors, as recommended by the WHO.”

Evidence of persistence raises clinical, epidemiologic questions

While Sow and colleagues’ findings provide additional evidence of long-term persistence of Ebola in semen, they also raise more questions on the epidemiology of the virus, Ian Crozier, MD, of the infectious diseases institute at Kampala, Uganda, wrote in a related editorial.

Along with the issue of infectivity — which Crozier notes has been complicated by a molecularly confirmed sexual transmission in Liberia — more data are needed to determine the true prevalence of persistent viral RNA in the full population of each country’s survivors, he wrote. Further, it is still unknown whether viral RNA persistence in semen has a clinical impact on the patient, or how host-pathogen interactions may influence immunopathogenesis or clinical predictors of persistence.

Additional study is required to determine what, if any, risk there is for outbreak resurgence due to sexual transmission, he wrote.

“While we stay tuned, an informed and respectful attention to safe sex practices in [Ebola virus disease] survivors remains one of their many urgent and important care needs,” Crozier wrote. “As well, a vigilant and nimble capacity in all three countries to rapidly detect and effectively respond to further flare-ups of [Ebola virus disease] related to sexual transmission from a survivor remains critical.” – by Dave Muoio

Disclosure: The researchers report no relevant financial disclosures.