Ground zero in Guinea: the Ebola outbreak smoulders – undetected – for more than 3 months

A retrospective on the first cases of the outbreak

On 26 December 2013, a 2-year-old boy in the remote Guinean village of Meliandou fell ill with a mysterious illness characterized by fever, black stools, and vomiting. He died 2 days later. Retrospective case-finding by WHO would later identify that child as West Africa’s first case of Ebola virus disease. The circumstances surrounding his illness were ominous.

The forest background

During the country’s long years of civil unrest, natural resources were exploited by mining and timber companies. The ecology in the densely-forested area changed. Fruit bats, which are thought by most scientists to be the natural reservoir of the virus, moved closer to human settlements.

Hunters, who depend on bushmeat for their food security and survival, almost certainly slaughtered infected wild animals – most likely monkeys, forest antelope, or squirrels. (WHO investigations into the origins of previous Ebola outbreaks have often found dead primates and other wild animals in jungles and forests). The wives of the hunters prepared the meat for family meals.

Though no one knew it at the time, the Ebola virus had found a new home in a highly vulnerable population.

Meliandou is located in what is today designated as the outbreak’s “hot zone”: a triangle-shaped forested area where the borders of Guinea, Liberia and Sierra Leone converge. All three countries were deeply impoverished, and their health infrastructures severely damaged, during years of civil unrest.

Poverty is pervasive. Large numbers of people do not have steady, salaried employment. Their quest to find work contributes to fluid population movements across extremely porous borders – a dream situation for a highly contagious virus.

Following the young boy’s death, the mysterious disease continued to smoulder undetected, causing several chains of deadly transmission.

Unclear beginnings

Later – in May this year – after the causative agent had been identified, a retrospective WHO investigation of that earliest event, headed by the Organization’s senior Ebola expert, Dr Pierre Formenty, traced the first 14 cases in great detail.

As Dr Formenty observed, these first cases yielded no strong or convincing hints, either from clinical features of the illness or the pattern of its transmission, of just what the causative agent might be, especially in a country with so much background noise from multiple other killer diseases.

But it was deadly, for sure: all 14 patients died, most within days after symptom onset. High-risk exposures were apparent (caring for a sick relative, preparing a body for burial, or delivering a baby) but again yielded no decisive clues. Alarm bells might have gone off had any doctor or health official in the country ever seen a case of Ebola. No one had. No alarm bells rang for the government or, for that matter, for the international public health community either.

As Dr Formenty noted, no one unfamiliar with the Ebola virus could have guessed so early on that this might be the cause. The WHO investigation also revealed a feature that would become a major driving force as the outbreaks in Guinea and elsewhere evolved: the very rapid movement of people from villages to Guinea’s capital and across the border into Sierra Leone. In an ominous hint of what would come, one of these first cases died in Sierra Leone.

The villagers were frightened and baffled. Their doctors were, too. The area is notorious for outbreaks of cholera and many other infectious diseases. Though cases of malaria have dropped in recent years, that disease remains the country’s most persistent and prevalent killer. Health authorities were on high alert but the causative agent still eluded them, camouflaged by early symptoms that mimic those of many other endemic diseases. Meanwhile the outbreak continued to spread, its causative agent still hidden.

Ebola virus on the move

Further retrospective investigations by WHO revealed how the earliest Meliandou cluster of cases ignited spread of the virus to other places. Chains of transmission that began with the illness and death of two midwives put more villages in crisis mode.

Ebola cases began to appear at a hospital in Gueckedou – a city in the same hot zone. At that hospital, the initial suspicions of the attending physicians focused on cholera. Of the nine patient samples tested for cholera, seven came back positive. It didn’t look exactly like cholera, but the tests used were sensitive and specific, and – once again – Ebola eluded detection.

As the investigation continued, links began to emerge between mysterious deaths in different locations. The dots of hotspots were becoming connected. Some single pathogen was likely at work, but which one?

Fortunately, staff from Médecins Sans Frontières (MSF) were already in the country, responding to a serious malaria outbreak. Later, MSF doctors would quickly shift gears to manage clinical care for the swelling number of Ebola patients.

By early March, Guinea’s health officials, MSF staff and WHO knew something strange and very worrisome was going on, but no one knew exactly what. More than three months after that end-December death, Ebola was nowhere on the radar screen of suspects for mysterious deaths in West Africa.

Deeply worried, MSF sent a report in mid-March to one of its most experienced and intuitive disease detectives at its office in Geneva. That expert immediately suspected a haemorrhagic fever, possibly caused by the Marburg virus (the largest-ever outbreak occurred in Angola in 2004–2005), or even Ebola – an unheard event for this part of the world.

Diagnosis

The Ministry of Health sent samples to the Institut Pasteur in Paris. The first news was shocking: the causative agent was indeed the Ebola virus. Who could ever have guessed that such a notorious disease, previously confined to Central Africa and Gabon, would crop up in another distant part of the continent? The news from subsequent virological analyses was even worse: this was Ebola Zaire, the most lethal in the family of five distinct Ebola species.

WHO published the official notification of Ebola on its website on 23 March. By that time, WHO had already shipped supplies of personal protective equipment to Conakry and activated its state-of-the-art centre for real-time outbreak tracking and response. The first medical teams, under the WHO Global Outbreak Alert and Response Network (GOARN) umbrella, were on the ground by 25 March.

Relentless spread of the Ebola virus

In the meantime, the virus had continued its relentless spread. The bad news got even worse as the virus successfully marched into Conakry and the first cases – which multiplied quickly – were confirmed there on 27 March. In Conakry and elsewhere, new cases hit like sparks from a fire landing on dry grass.

The brushfire had begun. By that time, flare-ups, as new transmission chains were ignited, could no longer be stamped out, even as foreign medical teams from the WHO GOARN umbrella and other partners continued to pour in.

The pattern that followed was heart-breaking as the all-out national and international response escalated and pressure to stop the virus became increasingly intense. On at least three occasions, prospects for nationwide control looked good and the countdown for a case-free 21-day incubation period began.

Breaths were held as Guinea looked ready to enter the second 21-day Ebola-free period required before WHO can declare the end of an Ebola outbreak. On each occasion, vigilance eased and the sense of emergency lapsed as local health officials assumed the outbreak was over.

The country never made it. As the deadline approached, cases suddenly flared up again in previously controlled villages and cities. In other instances, the virus marched on to infect previously untouched areas.

A regional challenge

Some observers have speculated that these tragic up-and-down cycles of apparent control followed by flare-ups demonstrate just how strong this Ebola Zaire virus has become. More likely, these events represent re-introductions of the virus into Guinea – with its notoriously porous borders – from the large outbreaks in neighbouring Liberia and Sierra Leone.

This more realistic explanation strongly suggests that control in Guinea will not be feasible until the Ebola caseload in its neighbours goes down. On current trends, the prospects that this will happen anytime in the near future are distinctly not good at all.

The fear factor

Today, one of the biggest barriers to control is violence from an impoverished, terrified and shattered population that does not understand what hit it and fights back the only way it can.

Last week, health workers in several parts of the country were viciously attacked by angry mobs, forcing some medical teams to flee for their lives. One team hid in the bush for more than a day. Others saw their vehicles vandalized and their medicines and equipment collected and publicly burned, as though such acts might work as a “cleansing” ritual.