A man’s Ebola relapse resulted in 91 new cases across the Democratic Republic of Congo during the 2018-2020 outbreak.
Between 2018-2020, the Democratic Republic of Congo (DRC) suffered the biggest Ebola outbreak of its history. Moreover, it was the world’s second-deadliest Ebola outbreak; it affected more than 3,000 people and claimed 2,000 lives. Now, a report published in the New England Journal of Medicine shines new light on the transmission of cases during the outbreak in DRC. According to the report, a 25-year-old’s Ebola relapse may be to blame for a transmission chain that caused 91 new cases across DRC during the 2018-2020 outbreak.
In December 2018, the 25-year-old motorcycle taxi driver received an Ebola vaccine after coming in contact with an infected person. 6 months later, he presented to a treatment unit in DRC with fever, nausea, chest pain, muscle pain, and weakness. Doctors conducted a PCR test and diagnosed him with Ebola virus disease (EBV). He received a treatment of monoclonal antibodies, and soon recovered. After two consecutive negative Ebola tests, he was discharged. He was further advised to return a month later for a semen test as the virus can remain in semen for over a year. The man’s semen tested negative, and he did not return for any additional follow-up testing.
However, in November 2019, 149 days after his discharge from the treatment unit, he again developed Ebola-like symptoms. He sought help from a traditional healer, but when his symptoms worsened community members shifted him to a specialized Ebola treatment unit. At the unit he was tested for HIV, malaria, and Ebola; out of which he tested positive only for Ebola. Two days later, he died.
Relapse vs Infection
Doctors conducted a genomic investigation to identify whether the man suffered an Ebola response or reinfection. Genomic sequencing revealed that the virus from his new illness was almost the same as his previous infection. The samples differed by only two mutations. Thus, confirming it to be a relapse.
Moreover, tests revealed that the man as asymptomatic for 8 days during his second infection. This resulted in him spreading the virus to 29 others who then spread it to 62 additional people.
The researchers did not find any evidence of immune deficiencies in the patient. Therefore, they hypothesize that the relapse may have occurred due to a vaccine failure. Moreover, researchers propose another alternate hypothesis which suggests that the antibody treatment did not evoke a strong immune response.
The report further adds to the evidence that the Ebola virus can remain in the body long after recovery. Thus, the World Health Organization (WHO) recommends monitoring survivors for at least 2 years.
Mbala-Kingebeni, Placide, et al. “Ebola Virus Transmission Initiated by Relapse of Systemic Ebola Virus Disease.” New England Journal of Medicine, vol. 384, no. 13, 2021, pp. 1240–1247., doi:10.1056/nejmoa2024670.