How did this Ebola outbreak emerge and what have we learned?
At the launch of the 2014 American Society of Tropical Medicine and Hygiene Conference in New Orleans, Bill Gates said the meeting was talking place at a critical moment in the history of global health — in the midst of an Ebola epidemic in a part of the world that had already been hit hard by other diseases as well as poverty and civil strife.
“I think it’s worth noting that this particular Ebola outbreak was a unique event in many ways. The disease had formerly presented itself in Central Africa; now it was in West Africa. It had limited itself to relatively under-populated areas; now it was in cities. It had tended to burn itself out after intense but relatively brief outbreaks; now it was becoming a sustained epidemic,” he said.
Over the course of the meeting, a number of other experts in tropical diseases provided further insight into how the Ebola virus had reached West Africa, why the epidemic had spun out of control, and what have we learned from it.
Where did the Ebola come from?
“When the species identification came back as Ebola Zaire virus everyone, including me, was very surprised. Our first question was how did this virus get all the way from Central to West Africa,” said Dr. Daniel Bausch of Tulane’s School of Public Health and Tropical Medicine in New Orleans.
“One of the possibilities is that the virus has always been there,” he said adding that unlike descriptions in the popular media, people do not necessarily present ‘with eyeballs melting’ or with other more pronounced symptoms of hemorrhagic fever.
“It turns out to be a difficult diagnosis to make in the early stages, and so it is not impossible that you can have some virus that circulates, and if you are lucky enough not to have nosocomial amplification and a large outbreak, it may go unnoticed,” he said.
There are some data to support this. Since Lassa fever is endemic to the region, specimens are routinely screened for Lassa, which is generally responsible for 30-40% of the acute febrile illnesses. To determine the causes of the other illnesses, researchers in Sierra Leone screened specimens collected between October 2006-October 2008 for antibody reactions to insect-borne and hemorrhagic fever virus antigens — and 8% tested positive for Ebola Zaire.
Most data suggest that bats are the reservoir for the virus, and there is a good chance that bats in the region harbor the virus — meaning that the potential for future outbreaks is significant. The virus may pass from animal to humans on a number of occasions but goes undiagnosed and dies out before it spreads far.
Late recognition in a weak healthcare infrastructure
“What usually happens is Ebola infection sort of bounces around from village to village for awhile. What converts this from a small outbreak, that no one ever knows about, is when someone gets into a hospital that isn’t really prepared for it,” said Dr Baush.
Most of the health facilities in the region were very poorly resourced, in terms of contact precautions, running water, soap, gloves and clean needles — so if someone comes into one of those facilities who is sick with Ebola, it could easily be spread to healthcare workers and other patients before the illness has been recognized.
“Meanwhile, unbeknownst to us, people were crossing between Guinea, Sierra Leone and Liberia. Many people in this part of the world identify more with their ethnic identities than their national ones. The border is an imaginary thing, and people cross back and forth,” said Dr. Bausch.
What do we usually do?
Once Ebola is recognized (and this can take months, since diagnostic capacity is limited in such settings), it is usually followed by an intense but relatively short (2-3 months) effort led by international teams.
This involves classical epidemiology:
• Case finding and isolation in Ebola Treatment Units (ETUs);
• Aggressive contact tracing and, if the contacts fall ill, move them into isolation in the ETU;
• Education and social mobilization efforts to promote healthy behavior and cooperation with community.
Why won’t the usual approach work now?
But in this setting — the poorest countries on earth with fledgling governments and under-developed health infrastructure — the epidemic quickly outstripped the local resources and international resources.
“To use a military analogy, each time you have a new case, it is a new front that opens, so you need a treatment center, but you also need the surveillance in the field, you need a laboratory to do diagnostics, and you need training for all the people who are working, and you need logistics and transport, and you need security — so each time it happens you think you can do this, but when so many new fronts open, how many fronts can you really operate on at once? You can make a plan for the situation now, but in two weeks, the situation may be completely different,” said Dr Bausch.
What are we doing or do we need to do now?
Funding is now coming from the US government, the Gates Foundation, the EU and others, but responding effectively to the Ebola outbreak will take a massive coordinated endeavor to scale up each element of the response effort.
“One of our big challenges is the logistics and the impediments to operationalizing what we want to do are not trivial,” he said. “Implementation takes time. And we don’t have a incredibly deep capacity for this anywhere in the world. MSF and the US CDC does this — we have lots of people with expertise, but we don’t have hundreds or thousands of people,” said Dr Bausch.
Leadership and communications must be streamlined. In some areas, the old paradigm of case finding and contract tracing is no longer possible — not when there are thousands of cases, so their surveillance must be decentralized or ‘ring surveillance’ implemented with isolation of villages.
As Bill Gates also said when he opened the conference, there must be more investment in research and an accelerated development of experimental therapies and vaccines, but there much also be an improvement in the basic standard of supportive medical care available in West Africa, to a level similar to what is available in the United States and Western Europe.
“The data are very promising if you can get people just basic medical care, where they can get a standard of care with good fluid repletion with electrolyte management, that they do very well with the disease,” said Dr Bausch.
Improving the standard of supportive care will decrease mortality and could increase health-seeking behavior in the community.
But where this is not available, all that can be provided are Ebola care units, with isolation to prevent transmission, and perhaps some oral hydration and food and ultimately palliative care. In some settings even this is not possible, and the only choice has been to support home care with the distribution of hygiene kits and some personal protective equipment to reduce transmission within the families.
Who is to blame?
Dr. Bausch said that there had been a lot of finger pointing about who was to blame for allowing this epidemic to spin out of control, but said the blame goes further back, and cited comments Bill Gates made at the opening of the conference.
“Some lessons are already out there and we need to act on them now: First, we need to strengthen health systems in developing countries so that they can respond to periodic crisis. This means building the capacity and resilience of national health systems so that they can identify outbreaks of any infectious disease at the out set and take steps to protect them,” said Gates.
Dr. Bausch stressed out that, with the exception of programs such as PEPFAR, the US government’s appropriations for global health have remained static since around 2003, and have actually not kept up with inflation — leaving the poorest countries in the world to fend for themselves. Now, the hardest-hit nations — Liberia, Sierra Leone and Guinea — clearly needed much more support to strengthen their own primary care systems as swiftly as possible.
Global Health Strategies generously supported Theo Smart’s attendance at the 63rd Annual American Society of Tropical Medicine and Hygiene Conference in New Orleans.