A new analysis pushed back the earliest known point of Congo’s Ebola outbreak to at least January, weeks before health officials on the continent officially declared the outbreak in mid-May.
The findings are from a study that included interviews with 97 people and point to the earliest cases on the edges of Mongbwalu, a mining town that has now become the epicenter of the world’s second-largest Ebola outbreak on record.
After the first chain of infection
Between mid-January and May 15, when Africa’s top public health agency proclaimed Congo’s 17th Ebola outbreak, researchers discovered more than 500 suspected cases. But that delay of about four months means the virus had been propagating and killing people long before anyone outside the affected regions knew there was an outbreak underway.
The article details a reconstruction of a very early known chain of transmission. It started on 25 January with a 50-year-old lady known only as A who vomited blood and died. Six days later her mother died. Her husband got sick but he got better.
That pattern — one case spreading through a family before spreading further — is consistent with what experts have told Reuters in the past: infections in Congo’s Ebola outbreaks tend to circulate for weeks or months before health authorities catch up and issue a formal proclamation.
Constructing a concealed outbreak
The researchers looked beyond hospital records to trace the early spread of the pandemic. They talked to nurses and doctors who had treated patients, community leaders, survivors and bereaved family members. They also interviewed coffin-makers and cemetery caretakers, people whose occupation brought them into direct touch with the dead at a time when Ebola had yet to be recognized as the cause.
In addition to interviews, the team included images, WhatsApp messages and physicians’ notes. In some cases they looked at funeral biographies, the short life stories commonly given out at burial rites in the area, and discovered that a few of them described symptoms consistent with Ebola infection. The facts, extracted from grief, not surveillance, gave researchers a mechanism to track the virus’s progress across families and communities before any formal reaction had begun.
A record-breaking scale
The outbreak has developed into the second biggest Ebola outbreak ever documented since then. The number of confirmed and suspected cases in Congo has risen to 3,532. The only other bigger outbreak was in west Africa in 2014-16 when the virus ripped through Guinea, Liberia and Sierra Leone and left 28,616 people infected before it was brought under control.
Unlike the Zaire strain responsible for most previous outbreaks in the country including the West Africa pandemic, the current outbreak in Congo is caused by a rarer strain of the Ebola virus called the Bundibugyo strain. There is no licensed vaccination or treatment, so responders have fewer weapons to combat the Bundibugyo strain than they would have against other common forms of the virus.
The Importance of the Delay
The four-month span from the first known death to the official declaration of the outbreak underscores a problem common in outbreak response: by the time health authorities confirm an epidemic and mobilize resources, the virus has often already established multiple chains of transmission in a larger area than initially understood.
Mongbwalu is situated in a mining zone and the constant flow of workers into and out of the mining sites could expedite the spread of a virus such as Ebola, which spreads by contact with bodily fluids of sick persons or contaminated surfaces. Before symptoms are severe enough to seek medical attention, or before the disease is specifically associated with Ebola, a sick worker in one region can transfer the virus to another.
The report’s focus on interviews with coffin-makers, cemetery workers and bereaved relatives also points to a broader trend observed in outbreak investigations: some of the most valuable evidence that can help reconstruct the true timeline of an epidemic is not found in clinics or laboratories, but in the people who deal with its aftermath. Funeral rites, burial logs and even the offhand life stories told at funerals were data pieces that helped researchers fill in the blanks left by a health care system that had yet to figure out what it was dealing with.
Next up
Now that the number of cases is above 3,500 and there is no vaccine for the Bundibugyo strain, the course of the outbreak will depend very much on how quickly the responders can identify remaining channels of transmission and isolate new cases. The report is retroactive, based on interviews and personal documents rather than real-time surveillance, and is intended as a reminder of how much of the early spread of the pandemic went unrecognized as it occurred.
Now public health experts reacting to the outbreak have to play catch-up with a virus that has a four-month head start. Each new case linked to that early era in Mongbwalu builds a picture of how far the outbreak had already spread before it had an official name, and how much of its full scale may still go uncounted in locations the investigation has not yet reached.
