No one knows exactly how bad West Africa's Ebola epidemic is

According to official estimates, there are more than 8,000 people in West Africa who have Ebola. But the real number is likely much, much higher.

"Under-reporting" has been a constant feature of the world's worst Ebola outbreak. Cases have gone missing, deaths are uncounted, and "there is widespread under-reporting of new cases," warns the World Health Organization.

The WHO has continually said that even its current dire numbers don't reflect the full reality. The estimated 8,000 Ebola cases in West Africa could just be the tip of the iceberg. Here's a breakdown of why so many cases go under-reported.

Why so many Ebola cases go under-reported

Health workers sterilize the house and prepare a body for burial in Lango village, Kenema, Sierra Leone. (Photo courtesy of Andalou Agency)

To understand how an Ebola case could be missed, you need to understand what it takes to actually find and count a case, a sequence of events that need to unfold perfectly to add a disease or death to national and international tallies.

Lina Moses, a Tulane University epidemiologist who has been working with Sierra Leone's Ministry of Health on the surveillance effort, describes the process as "complicated" and "challenging."

In the country, potential cases are communicated through dedicated hot-lines, which citizens can call in to report on themselves or their neighbors. Health workers or doctors can call in cases, too. These reports are forwarded to surveillance response teams in the country's relevant districts, like US states.

But all these cases need to be followed up on and verified to be counted. To do that, a team of two to four investigators is dispatched to hunt for the suspected Ebola victim.

A soldier inspects a woman with an infrared thermometer for signs of fever at a check point in Nikabo, a village in Kenema, Sierra Leone. (Photo courtesy of Andalou Agency)

Tracking down Ebola cases is difficult in places where the roads and communication infrastructure are poor.

Actually tracking these people down isn't straightforward, especially in areas where the roads and communication infrastructure are poor. "It's a wild goose chase," says Moses. "You go to a neighborhood, and start asking around, ‘Have you heard of the person who is sick?' The investigators can spend all day chasing one rumor."

These health teams work under constant stress and uncertainty. During this outbreak, they've faced violence, angry crowds, and blockaded roads. They can't wear protective gear because they'll frighten locals. They do their jobs while maintaining a distance from the people they're trying to get information from and staying outside of potentially contaminated houses.

When they finally locate an Ebola victim, he or she may not always be lucid enough to talk or even still alive. So the investigators need to interview friends, family or community members to determine whether it's Ebola that struck.

If this chase appears to have led to an Ebola patient, the health team notifies a dispatcher to have that person transported by ambulance to a nearby clinic or Ebola treatment center for testing and isolation.

If the person is already dead, they notify a burial team, which arrives in full personal protective gear. They put the body in a body bag, decontaminate the house, swab the corpse for Ebola testing, and transport the body to the morgue.

A group of volunteers wash their hands ahead of sterilizing the bodies of people who died from Ebola in Kenema, Sierra Leone. (Photo courtesy of Andalou Agency)

But confirming the cause of death doesn't always happen. There have been reports that mass graves hold uncounted Ebola cases. "[Counting] deaths depend on the Ebola treatment center being able to link up to lab and surveillance teams to accurately report the death to the ministry," says Moses. With limited resources, this is not a priority. "Saving people is their priority."

Reported cases are then communicated to the ministry of health in the country. These reports are combined with counts from NGOs and other aid organizations working in the region. The numbers come in three forms: lab-test confirmed cases, suspected cases, and probable cases. The WHO classifies a suspected case as an illness in any person, dead or alive, who had Ebola-like symptoms. A probable case is any person who had symptoms and contact with a confirmed or probable case.

The ministry of health compiles and crunches this information and sends it to the WHO country office. They then report that to the WHO's regional Africa office in Brazzaville, Congo and that message is passed along to Geneva, home to WHO's headquarters.

"At each step along the way the case can fall out of the pool of 'counteds.'"

To get to this point, Dr. David Fisman, an infectious disease modeler working on Ebola, summed up: "A person needs to have recognized symptoms, seek care, be correctly diagnosed, get lab testing — if they're going to be a confirmed case — have the clerical and bureaucratic apparatus actually transmit that information to the people doing surveillance. At each step along the way the case can fall out of the pool of 'counteds.'"

Many Ebola cases are still in hiding

The cultural and socioeconomic setting have an impact on case counts. So do basic emotions. The chain of events for reporting cases has been interrupted by the fact that some Ebola victims go underground for fear of being taken away from their families.

"Communities are so afraid, so distrustful about what's going on."Imagine being the mother of a son who you think might have Ebola. You know your child might die, and you know that if you call authorities, he will most certainly die alone, far away from you, in an isolation ward where you can't console him. Do you call that hot-line? "Communities are so afraid, so distrustful about what's going on," says Moses. "It's hell. It's devastating to the social fabric in communities, in towns and villages."

This is compounded by denial about the disease. Though denial is less prevalent now, more than six months into the epidemic, for a period at the beginning — when Ebola emerged for the first time ever in West Africa — people just didn't believe it was real.

"People thought the government was making it up, that it's an excuse for the government to get money for all these different agencies," says Moses, "or it's a political plot to try to murder people in the east because people in the east belong to the opposition party."

Poverty makes tracking Ebola much more challenging

A Liberian health worker interviews family members of a woman suspected of dying of the Ebola virus  in Monrovia, Liberia. (John Moore/Getty Images)

Poverty in West Africa makes every step of the reporting process more challenging. If sick people in rural and remote areas of the Ebola-affected countries don't have the resources or wherewithal to make it to the hospital, or the phones to call Ebola hot-lines, their cases will never be counted.

Beyond individual barriers, there are poverty-related systemic barriers. To say these countries are under-resourced is putting it mildly, and their health systems have been overwhelmed by the disease. WHO spokesperson Dan Epstein says, "There's not enough health workers in the three affected countries to be able to compile the reports, forward the reports, investigate the reports."

On average, Sierra Leone spends $96 per person on health care per year. Guinea spends just $32 and Liberia spends $65.West Africa is home to some of the poorest countries on the planet. On average, Sierra Leone spends $96 per person on health care per year. (Guinea spends just $32 and Liberia spends $65.) Canada, meanwhile, invests $5,741 and the United States, $8,895.

In Sierra Leone, each district only has two surveillance officers. "Imagine entire states in the US only having two people whose job it is to followup on diseases," says Moses. "I haven't met a surveillance officer who isn't outstanding. But there are two of them, and when Ebola exploded in Sierra Leone, how can two people handle a disease they have never seen before?"

Even in the resource-rich US, finding Ebola has proved to be challenging. Consider the recent case of Thomas Eric Duncan, a Liberian national who flew to Dallas, days after helping care for a dying Ebola patient. When he showed up in a Dallas hospital — with a fever and a travel history that should have raised red flags — he was turned away on his first visit, sent back into the community already contagious and potentially spreading the disease to others.

In some ways, his case is an odd parallel to that of the dying Ebola patient he brought to a Liberian hospital days before his journey to America. She, too, was turned away from the hospital. Like Duncan, she went back into the community, already infectious and shedding the virus, potentially passing it to Duncan and others.

There are 8,000 Ebola cases. The real number is higher

We can only hope that America's botched attempt to identify its first Ebola case puts other surveillance systems and hospitals in the US — and all over the world — on alert for the disease. But the reality is that identifying and counting cases will be difficult everywhere, especially with the onset of flu season.

For now, experts say we have only hit the tip of the iceberg in West Africa. There's no way to know how vastly under-reported this epidemic is, but there are estimates being floated around. Comparing surveillance figures with actual hospital beds dedicated to Ebola care in West Africa, the Centers for Disease Control and Prevention suggested that under-reporting could be happening at a rate of 2.5. This means that every one case reported equals 2.5 on the ground.

If true, today's 8,000 Ebola cases could actually be 20,000. Not knowing where Ebola is lurking, and to what extent, has knock-on effects. Because of the lack of reporting in Sierra Leone, the disease caught surveillance teams and epidemiologists like Moses off-guard. "Ebola just exploded rapidly." By the end of May, there were nearly 60 cases in Sierra Leone. By the end of June, there were nearly 100. By the time she returned to the US, in September, there were more than 2,000 cases there.

"We were not prepared for the scale, the speed, the complete devastation that this disease caused.  No one was." The country has resorted to unprecedented measures like controversial nation-wide, multi-day, lock-downs to stop the spread of the disease and find hidden cases. "If we were prepared, we wouldn't have these numbers we have now," added Moses. "It wouldn't be out of control."

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