Why health officials do not have a good handle on the current Ebola outbreak

The key to ending any infectious disease outbreak, especially one for which there's no approved vaccine, like the ongoing Ebola outbreak in the Democratic Republic of Congo, is getting slightly ahead of the virus.

To do that, health officials need to quickly identify the possible routes a virus might spread, a practice known as contact tracing, says Armand Sprecher, an infectious diseases physician with Doctors Without Borders.

"We find a sick person and say, 'Who was in contact with that sick person? Who took care of them? Who did their laundry, who touched them? Or who went to a burial where somebody had died of this?'" he says.

Spread by bodily fluids, the virus can only travel to these contacts. Identifying them all quickly, informing them of their exposure and keeping tabs on them can help prevent them from spreading the virus to others and get care faster if they develop symptoms. "It's labor-intensive, but if you can do it well, you've got a really good handle on the outbreak," says Sprecher.

Health officials do not have a good handle on the current outbreak.

Just over two months in, over 1,000 people have died, and more than 2,400 people have been sickened by the virus. Daily case counts show no signs of slowing down. Perhaps most concerningly, more than 80% of new cases are popping up outside of known contacts.

"That is an alarm bell for me," says Nahid Bhadelia, an infectious disease physician at Boston University who has worked on previous Ebola responses. "It means that a lot more people have this disease than we think, and contact tracing is not keeping up."

That high percentage could stem from the inability to trace all contacts of cases, giving them only a partial view of known transmission chains.

The outbreak is centered in a region with a lot of transient workers and ongoing conflict, which can make it difficult to track down everyone who comes into contact with a known case. More contact tracers would help, and the World Health Organization (WHO) announced that 21,000 community workers are being trained right now.

But it's also likely that entire chains of transmission are occurring outside the view of health officials before a very sick — or dead — person gets on their radar. "There's probably a lot more cases that we're missing," says Bhadelia. "This means people are presenting much later to care, which means their survival rates could be lower."

Many people aren't coming to clinics at all. Roughly two-thirds of deaths occur outside of the health system, according to WHO.

"There are still lots of people with symptoms that could be consistent with a concern for an Ebola diagnosis that are going 'underground,'" says Boghuma Titanji, an infectious disease physician at Emory University. Instead, she says they may be seeking care with traditional healers, staying home with family or unable to access — or even purposefully avoiding — treatment centers.

"It's important to remember that there's a lot of stigma associated with Ebola," she says. And where this outbreak is unfolding, there's "lots of mistrust toward the medical science and the people who are investigating the outbreak."

The fact that so much sickness and death is happening in the dark, outside the view of health officials and clinicians, has made responding harder, says Titanji. "I view it as just seeing the tip of the iceberg, but not being able to see just how big that iceberg is because we just don't have the lens that allows us to see that."

Improving that view, in part, will require building trust with affected communities. That's hard work, says Bhadelia, but some recent good news in the response could help — the start of clinical trials for treatments and a drug that could protect exposed people from getting sick.

"I think that you can build trust by providing better care," says Bhadelia, "and that better care can, of course, be access to potentially promising treatments."

Access to these therapies is still quite limited, since they're only available through clinical trials. But Bhadelia hopes that over time, the prospect of receiving better care or a drug that could prevent disease after an exposure could attract more people to seek help through clinics or contact tracers. Ultimately, she says that's what's needed to reduce the toll of this outbreak and get it under control.