A woman who survived Ebola in July 2014 may have infected her husband and two sons more than a year later,with the one son dying, report researchers at the US Centres for Disease Control and Prevention, Atlanta, highlighting the need for “continued surveillance”.
According to the research, the seeming virus “flare-up” killed one of the boys, a 15-year-old.
The boy tested positive for Ebola in Monrovia, Liberia, on 19 November, 2015, and died four days later, it said. His father and 8-year-old brother also tested positive for Ebola RNA – molecules that convey DNA instructions – and experienced symptoms such as tiredness, headache and fever. Both recovered.
The mother was also tested but had no traces of Ebola RNA, said the research team. However, she carried Ebola antibodies, indicating she had previously been infected and that her body had launched an immune response to fight off the virus. Further tests “suggested that she survived an acute Ebola virus infection in July 2014”, the researchers are quoted in the report as saying.
The virus appears to have “re-emerged” after the woman gave birth to a fourth son, “making the infection flare up in October 2015, then transmitting the virus to her family”, it added. Liberia was declared free of human-to-human Ebola virus transmission in May 2015.
The report says the virus carried by the father and two sons appears to have been a “continuation” of the 2014 outbreak, when the mother was infected while taking care of her brother who died of Ebola. The couple’s baby boy also had Ebola antibodies, which he likely got through his mother’s milk, the researchers said.
This was the first known case of transmission from a “persistently infected” Ebola survivor.
The report says it was already known that the virus, which caused a major outbreak in Sierra Leone, Liberia and Guinea in 2013-15 in which more than 11,300 people died, can persist for many months in semen, in the eye, and in breast milk of women infected while pregnant.
But, the World Health Organisation has said that transmission by people who beat infection is “rare”. “Exactly how the virus was passed from family member to family member remains unclear, but the authors suggest it could be close physical contact or contact with body fluids,” said the study.
The report says Ebola was first identified in what was then Zaire – now the Democratic Republic of Congo – in 1976. Since then, there have been several outbreaks, of which the west African outbreak was the deadliest by far.
Often contracted from eating infected bushmeat, the virus can be transmitted from person to person via the blood, certain body fluids, or organs of an infected or recently deceased person. Transfer can happen by touching a sick or dead person, and likely also sexual intercourse, research has shown.
On average, the virus kills about half of the people it infects.
Background: Outbreak response efforts for the 2014–15 Ebola virus disease epidemic in west Africa brought widespread transmission to an end. However, subsequent clusters of infection have occurred in the region. An Ebola virus disease cluster in Liberia in November, 2015, that was identified after a 15-year-old boy tested positive for Ebola virus infection in Monrovia, raised the possibility of transmission from a persistently infected individual.
Methods: Case investigations were done to ascertain previous contact with cases of Ebola virus disease or infection with Ebola virus. Molecular investigations on blood samples explored a potential linkage between Ebola virus isolated from cases in this November, 2015, cluster and epidemiologically linked cases from the 2014–15 west African outbreak, according to the national case database.
Findings: The cluster investigated was the family of the index case (mother, father, three siblings). Ebola virus genomes assembled from two cases in the November, 2015, cluster, and an epidemiologically linked Ebola virus disease case in July, 2014, were phylogenetically related within the LB5 sublineage that circulated in Liberia starting around August, 2014. Partial genomes from two additional individuals, one from each cluster, were also consistent with placement in the LB5 sublineage. Sequencing data indicate infection with a lineage of the virus from a former transmission chain in the country. Based on serology and epidemiological and genomic data, the most plausible scenario is that a female case in the November, 2015, cluster survived Ebola virus disease in 2014, had viral persistence or recurrent disease, and transmitted the virus to three family members a year later.
Interpretation: Investigation of the source of infection for the November, 2015, cluster provides evidence of Ebola virus persistence and highlights the risk for outbreaks after interruption of active transmission. These findings underscore the need for focused prevention efforts among survivors and sustained capacity to rapidly detect and respond to new Ebola virus disease cases to prevent recurrence of a widespread outbreak.
Emily Kainne Dokubo, Annika Wendland, Suzanne E Mate, Jason T Ladner, Esther L Hamblion, Philomena Raftery, David J Blackley, A Scott Laney, Nuha Mahmoud, Gloria Wayne-Davies, Lisa Hensley, Eric Stavale, Lawrence Fakoli, Christopher Gregory, Tai-Ho Chen, Augustine Koryon, Denise Roth Allen, Jennifer Mann, Andrew Hickey, John Saindon