Rwanda identifies index case for current Marburg virus outbreak

In Rwanda, efforts to control an ongoing outbreak of Marburg virus disease, a deadly Ebola-like filovirus, continue. The country declared the outbreak on Sept. 27 and had recorded 63 cases and 15 deaths as of Oct. 23.

In a press briefing on Oct. 24, Rwanda’s health minister, Sabin Nsanzimana, confirmed that the virus that started the outbreak originated in an animal.

In an earlier meeting, on Oct. 20, Nsanzimana had revealed that it's very likely the first human Marburg virus disease case in the current outbreak was in a 27-year-old man who had been exposed to fruit bats in a cave where mining occurs. The individual had sought treatment at Kigali’s King Faisal Hospital, where he was first diagnosed with and treated for malaria, and Marburg was detected only later. By then, the infection had spread to his close contacts and several health-care staff.

Researchers have known Egyptian fruit bats to be the primary reservoirs of Marburg virus (PLOS Pathog. 2012, DOI: 10.1371/journal.ppat.1002877). Nsanzimana said that mining activities at the site linked to this index case have been stopped and that public health officials are following up with people who worked in the mine. “That is the current focus for us,” he said at the Oct. 24 meeting, “to ensure that these fruit bats living in caves are not interacting with humans.”

On the social media platform X, Yvan Butera, Rwanda’s minister of state in the Ministry of Health, shared genome-sequencing results of the Marburg virus isolated from outbreak patients. The analysis revealed that these virus sequences were closely related, including four that were identical, indicating that the virus had spread rapidly in a short period, he wrote. In the same X thread, Butera also mentioned that all the analyzed sequences share a single zoonotic origin, suggesting a single jump from bats to humans.

Another find was that the currently circulating virus shares a common ancestor with a Marburg virus strain that was circulating in 2014. The strain causing the ongoing outbreak in Rwanda “shows a limited mutation rate,” Butera wrote, “which is a good sign.”

So far, more than 1,200 people in the country—health-care workers and close contacts of infected individuals—have received an experimental Marburg virus vaccine. Public health officials are also using therapeutics, including the antiviral remdesivir and an experimental monoclonal antibody called MBP091, to treat infected individuals. As of Oct. 23, 46 people have recovered and two infected individuals are currently isolated and receiving treatment.