Ebola Resource Center

Ebola Resource Center

June 22, 2018
3 min read

Ebola flare-ups in West Africa linked to ‘persistently’ infected survivors

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Researchers linked eight flare-ups of Ebola virus disease that occurred in West Africa after the peak of the region’s 2-year epidemic to survivors who became “persistently and subclinicially infected” following an acute Ebola virus disease episode.

“Because scientific evidence of persistent infection and its possible consequences is now available, counseling should be prioritized, because often survivors of the West African outbreak were unaware of the risk they represented to their relatives,” Ibrahima-Soce Fall, DrMed, MPH, PhD, MSc, FFPH, regional emergencies director at WHO’s Regional Office for Africa, and colleagues wrote in The Journal of Infectious Diseases.

More than 29,000 people were infected in the Ebola virus epidemic in West Africa from 2014 to 2016 and 11,310 died. The epidemic left behind 17,000 survivors — the largest cohort of Ebola survivors in history, according to the researchers.

Previous studies have shown that some Ebola survivors have antibodies 40 years after recovery, and that many Ebola infections may go unrecognized. The virus can be detected in semen up to 18 months after recovery, according to Fall and colleagues. It can persist in other bodily fluids, including breast milk and the eye’s aqueous humor.

To better understand the risk for Ebola resurgence, Fall and colleagues reviewed data on eight flare-ups in West Africa that were documented since January 2015, when the number of new cases in the region started to decline. The flare-ups occurred up to 11 months after the first Ebola-free status declaration was made by WHO in May 2015.

According to the researchers:

  • The first flare-up was linked to male-to-female sexual transmission that occurred in Liberia 5 months after the male Ebola survivor was discharged from an Ebola treatment unit.
  • The first identified case of the second flare-up was a 17-year-old boy in Liberia who died more than 1 month after the country was declared free of Ebola. Investigations revealed that he was one of five confirmed cases who recently consumed meat of a slaughtered dog. However, a sample of the dog carcass was negative for EBOV. Two additional cases were reported during this resurgence, which Fall and colleagues said may have been caused by an unidentified survivor.
  • The third flare-up occurred after EBOV was identified in a 9-month-old baby who died in Guinea. The strain was similar to a strain isolated from the breast milk of the baby’s mother. Molecular sequencing revealed both the mother and father were undiagnosed survivors.
  • The fourth flare-up was identified after officials discovered an EBOV-positive postmortem swab 50 days after the last confirmed cases were detected in Sierra Leone. The case was linked to male-to-female sexual transmission. The daughter of the deceased woman also contracted Ebola, possibly when caring for her mother. Six additional cases were identified during this resurgence.
  • Similarly, sexual transmission may have been the source of the fifth flare-up. The wife of an Ebola survivor in Guinea developed an infection that initially went unrecognized. Her brother, who also became infected, may have been exposed to EBOV while caring for her.
  • The sixth flare-up occurred in Liberia 3 months after the second declaration of Ebola-free status in the country. Although there was limited evidence, the three confirmed cases were linked to a persistently infected individual.
  • Likewise, the seventh flare-up occurred 2 months after Sierra Leone was declared free of Ebola for the first time, but investigators could not definitively locate the source of the infection.
  • The final flare-up was detected after three deaths in the same community were classified as probable Ebola cases. Soon after, EBOV was found in blood samples of contacts who attended funerals of the initial three cases. The source of the resurgence was linked to a survivor whose semen tested positive for EBOV nearly 17 months after recovery. Overall, 13 probable and confirmed cases were identified during this resurgence.

In addition to these flare-ups, Fall and colleagues warned that other events “surely happened” but went unnoticed. After reviewing these cases, the researchers said they recommend that survivors’ body fluids be monitored for at least 18 months after recovery or until their fluids test negative at least twice. They also called for counseling and sexual health education for survivors, as well as the implementation of other preventive measures, such as vaccination of contacts and screening blood and semen donations.

“Working groups led by Ebola experts and coordinated by WHO are ongoing to update recommendations on how to best structure and implement such follow-up programs,” they concluded. – by Stephanie Viguers

Disclosures: The authors report no relevant financial disclosures.