Pandemic

V8 engine, pulled the shift lever into ‘drive’ and raced off down the street.

Traffic was heavy at the intersection, so Hardin reached down and flicked a couple of switches on the dashboard. Two red lights fitted behind the radiator grille began alternately flashing, and a two-tone siren started its discordant wailing. Traffic parted, Hardin hauled the steering wheel around to the right and floored the gas pedal.

Eighteen minutes later he walked into the CDC and three minutes after that he opened the door to Walter Cross’s office. Cross was Hardin’s immediate superior and head of the Special Pathogens Branch, but the two men had worked together for so long that they were firm friends.

They had to some extent been thrown together by their qualifications. Although the Centers for Disease Control is a major organization, employing around seven thousand people and with an annual budget in excess of two billion dollars, there are exactly eight employees who are qualified to work in the Bio-Safety Level 4 laboratory. One was Walter Cross, the Head of Special Pathogens – a highly specialized department within the Division of Viral and Rickettsial Diseases – and another was Tyler Hardin.

The CDC BSL4 laboratory is one of two maximum-safety biological research laboratories in America, and one of only six in the entire world. Entry is by ID card and a personal identification code punched into a keypad by a scientist wearing a totally sealed biological spacesuit, who even then has to enter through a negative-pressure airlock, to ensure that air can only bleed into the laboratory and never out of it, and a powerful decontamination shower.

Only inside one of these secure laboratories is it safe to examine any of the handful of microscopic and utterly lethal species-killer viruses.

Viruses are usually named after the places where they were discovered, and the first of what became known as the species-killers emerged in 1967 in Marburg in Northern Germany. The Marburg virus arrived at the Behring Works factory inside an infected African green monkey, the kidney cells of these animals being used by Behring to produce vaccines. Somehow, the Marburg virus jumped from the monkey into the immediate human population working at the factory. By the time the outbreak was over, thirty-one people had been infected and seven were dead. Marburg proved it had about a twenty-five per cent lethality.

Marburg is a type of organism known as a filovirus, one of a small and highly lethal family of haemorrhagic fever viruses, which closely resemble one another but which bear little resemblance to other known viruses. Under the impartial gaze of an electron microscope, the reason for the appellation filovirus (from the Latin filo, meaning ‘thread’ or ‘threadlike’) becomes immediately obvious, the shape of the virus being just that.

Marburg was the first, but unfortunately it wasn’t the last.

The Ebola River is a tributary of the Congo or Zaire River and, just under ten years after Marburg began its rampage in Germany, a new and even more deadly filovirus emerged from the rainforest. Named Ebola Zaire after the river and the country, it appeared almost simultaneously in over fifty native villages scattered near the headwaters of the Ebola River, and killed nine out of every ten people who became infected.

Ebola Zaire was and is the most lethal fast-acting virus the world has ever seen, killing its victims in a matter of days, spreading easily and swiftly through any close-knit population through body-fluid exchange. A drop of infected blood on a cut finger is quite enough to start the infection.

It is popularly believed that Ebola attacks every organ in the body apart from skeletal muscle and bone, multiplying at a terrifying rate and converting body tissues into active virus particles. It is reported to liquefy the internal organs, resulting in uncontrollable bleeding from every orifice.

In fact, it does nothing of the sort. Almost all these ‘facts’ – repeated in countless books, magazines, television programmes and films – are either simply fiction or misconceptions promulgated by writers who haven’t bothered to do their research. True, Ebola does multiply at a terrifying rate, and uncontrollable bleeding from every orifice does frequently occur during the terminal stages of the disease.

But Ebola actually attacks only the circulatory system, and merely two components of that. It targets the platelets responsible for blood clotting, and the endothelial cells that line the inside of veins and arteries and essentially keep the blood contained inside. It launches, in effect, a two-pronged attack: the circulatory system begins to leak as the endothelial cells fail to function, and the blood that then leaks out doesn’t clot.

The effects are usually first apparent in those organs where the membranes are the thinnest and most vulnerable: typically the lungs, eyes, mouth and nose. Tissues and organs become soggy as they fill with blood; the lungs stop functioning properly; blood enters the digestive system; the throat becomes bloody and infected, making swallowing impossible; blood leaks from the eyes and other orifices; in the latter stages brain functions become erratic and then cease almost entirely, as the skull fills with blood.

Again contrary to popular belief, a notable peculiarity of Ebola and the other viral haemorrhagic fevers is that the organs themselves are not destroyed. Despite the huge amounts of blood present in them, the actual tissues of the organs remain perfectly healthy – in effect, they have ceased to function because they have drowned in blood. And if a patient does manage to survive an attack by Ebola, he or she will normally suffer no lasting ill- effects: once the virus has been eliminated from the body, the organs will begin working normally once again.

In short, an attack by Ebola is essentially functional – the virus attacking the whole body through the circulatory system – rather than biochemical, in that there is no destruction of cells or organs. The attack is always very fast but the recovery, if the patient is lucky enough to survive, is also both fast and complete.

But one other popular ‘fact’ is true: in the latter stages of the infection, one drop – a single millilitre – of a victim’s blood can contain as many as one hundred million virus particles.

The Ebola virus is an extremely simple yet very mysterious organism. Like the other filoviruses, it is a microscopic thread visible only at magnifications in excess of one hundred thousand, and is characteristically very twisted and convoluted at one end – a feature that some virologists call the ‘shepherd’s crook’ or the ‘eyebolt’.

Structurally, it consists of a single strand of ribo-nucleic acid, containing the virus’s genetic code, encased in a sheath of structural proteins of seven different types. Three of these proteins are partially understood, but virtually nothing is known about the other four. The structure and function of these four proteins is a mystery, but the combination in Ebola is lethal – the virus appears specifically adapted to attack the circulatory system, and the human immune system seems completely incapable of fighting back.

It is also, using the tense terminology of the virologists, a badly adapted parasite. A well adapted parasite lives in some kind of harmony with its host: the relationship becomes almost symbiotic, and both host and parasite will survive. Ebola can kill its human host within days, and will itself die unless it can migrate rapidly to another human being.

This fact suggests that Ebola has another host somewhere, some animal or bird living in the tropical rainforest in Zaire which carries the virus but is essentially unaffected by it, yet nobody has any idea what that host might be. It also implies that either Ebola has mutated naturally, or it has been manufactured, to become capable of attacking the human immune system.

In its effects, if not in its appearance, it does resemble some other viruses. It appears to be distantly related to those which cause mumps, measles and rabies, for example, and also pneumonia and influenza. But these are all benign compared to Ebola and, unlike them, there is no known cure or even treatment for attack by a filovirus.

Marburg, Ebola Zaire and its slightly less lethal cousin Ebola Sudan, which has only about a fifty per cent lethality, are all classed as Level Four Hot Agents – L4HA – hence Hardin’s speed of reaction once he had read the message on his pager.

‘What have you got?’ Hardin demanded immediately, as he shouldered open the door.

‘It sounds quite like Ebola,’ Walter Cross explained, ‘but if the agent is a filovirus, it’s a hell of a long way from home.’

‘Where is it, then?’

‘Crete,’ Cross replied shortly.

‘That’s Crete as in Crete in the Mediterranean?’ Hardin’s surprise was obvious in his voice.

‘Yup. We – or to be accurate you – are going to have to go in to confirm it, but the message from the reporting doctor makes it sound pretty much like a filovirus infection of some sort. Maybe even some kind of totally new strain.’