by Wilson da Silva
ANXIOUS SCIENTISTS in space helmets and bubble suits. Troops blockading cities, while panicked citizens try to break through quarantine lines. A doomsday virus spreading rapidly, its victims bleeding through the eyes while their organs turn to mush. No cure, no antidote, no vaccine. And no idea from where this mystery killer came from.
If only this was science fiction. But these scenes have already flashed across television screens this year, during the outbreak of Ebola virus in Zaire, where the deadly pathogen slaughtered hundreds. And it will kill again. Only next time, the world may not be so lucky: the spread may not be contained.
Speak to scientists, and they will tell you that we may have to become more accustomed to such scenes in the decades ahead. Because Ebola, like a host of ‘emerging viruses’, has the capacity and the voraciousness to spread. And conditions have never been better for such emerging diseases.
“The conditions of the modern world are uniquely favourable to the rapid global spread of infectious diseases,” says Professor Jonathan Mann of Harvard University in Boston, a former head of the World Health Organisation’s AIDS program.
“A person harbouring a life-threatening microbe can easily board a jet plane and be on another continent when the symptoms of illness strike. Few habitats on the globe remain truly isolated or untouched, as tourists and other travellers penetrate into the most remote and previously inaccessible areas in their search for new vistas, business or recreation.
“AIDS has demonstrated how swiftly remote or seemingly obscure health events elsewhere can become tomorrow’s health crisis.”
A leading authority on infectious diseases, Mann and a number of other leading medical researchers have been agitating governments to set up a global disease monitoring system, capable of reacting to emerging microbial crises. He says that the world’s next pandemic may well be circulating now, spreading and growing – as AIDS did – without our knowledge. Take the spread of AIDS – a review of the history of HIV’s appearance suggests that the pandemic could easily have escaped detection for another five years or more, he says.
More and more scientists, fearful of the rise of new infectious diseases, are urging a determined and sustained global response. They have good reason for being worried. The world at the end of the 20th century is a paradise for infectious diseases. Microbes thrive on large numbers of people living close together, and there’s never been more of that than in the 1990s.
Less than a century ago, only 15 per cent of the world’s population lived in cities. Two decades from now, more than half of humanity will live in urban centres, most of them the ‘megacities’ of the Third World. By then, some 24 metropolises are expected to have populations exceeding 10 million, mostly in countries that can ill afford the civil and health infrastructures that reduce health risks. They could be the ideal factories for the incubation and eventual propagation of deadly outbreaks.
Then there’s international air travel. More than one billion passengers fly on airlines every year, and more than 300 million of these take trips across national borders. Air travel continues to rise, having grown 17-fold since the 1950s. Couple this with urban expansion into ecological niches rarely visited by humans, such as rainforests, the burgeoning but untraceable trade in sex tourism, and the widespread use of unsterilised needles – both in the under-equipped hospitals of poor nations and among drug users in the industrialised – and you have the perfect setting for an apocalypse.
It is a bomb waiting to explode. The only question is when. And which of the emerging diseases is going to be first. As Nobel laureate Dr Joshua Lederberg has said: “The microbe that felled one child in a distant continent yesterday can reach yours today, and seed a global pandemic tomorrow.”
AT FIRST, it triggers nausea and discomfort. Within hours, this is followed by high fever, then bleeding gums and a vomiting of blood. Lots of blood. Inside the body, the tissue walls of organs begin to break down, haemorrhaging profusely. Victims bleed from every orifice, and continue to vomit blood and tissue even while unconscious. There is an occasional sound of tearing as organs rupture and intestinal linings are coughed up. Between three and five agonizing days later, the victim is dead, their insides liquefied, their organs disintegrated.
This is Ebola, the most frightening of the new diseases to appear this century. If there was ever a doomsday plague, Ebola certainly qualifies. It is known to have caused major outbreaks in humans only twice since it was first identified in 1976. Was it to spread widely, it could slaughter hundreds of millions around the world, researchers ask. But there are other deadly new pathogens, as well as the re-emergence of diseases once thought vanquished and which, in the 1980s and 1990s, have shown a remarkable resistance to the pharmaceutical arsenal of the medical world.
Last year, Australian scientists came across the world’s newest emerging virus: Equine morbillivirus, a previously unknown organism that appeared without warning, killed 14 horses in north-eastern Australia within days and hospitalised two men, one of whom died a wheezing, ghastly death.
“No one can work out where the viruses go between outbreaks, and no one’s found the reservoir,” says senior scientist Margery Kennett of Fairfield Hospital in Melbourne, which houses one of Australia’s high security ‘hot labs’ for highly infectious diseases.
“It appears and disappears, and no one knows exactly how it’s transmitted. One ‘index’ case suddenly appears, and he’s bleeding like mad and all of a sudden, there’s another 10 and it grows exponentially after that,” she says.
Of the emerging viruses identified so far, Ebola is the most feared, classed as a ‘Biohazard Level 4’ – the highest level of risk. “The only thing you can do is try contain it,” says Professor Frank Fenner, an internationally renowned virologist at Canberra’s Australian National University. “There’s no vaccine, no drug that has the slightest effect on it.”
At its previous known epidemic appearances, in 1976 and 1979, Ebola killed hundreds in Zaire and then Sudan before it was contained. It then disappeared. Another outbreak took place at an American research facility in Reston, Virginia, in 1989, when an infected monkey imported for experimentation transferred the virus to others, and scores of the creatures died. A number of lab workers also became ill. Luckily, this strain of the virus, although it looked exactly the same under the microscope, was not lethal to humans.
Ebola is a filovirus, or ‘thread-shaped’ virus, of a type which has only been seen by scientists once before. The first sighting of a filovirus was in 1967 when laboratory staff in Marburg, Germany, fell violently ill after handling a shipment of African green monkeys from Uganda. Dubbed the ‘Marburg virus’, this first recorded outbreak hospitalized 31 people, of which seven died. Only three cases since have been definitively blamed on Marburg virus.
Another pathogen on the nasty list are Arenaviruses, of which Lassa and Hantaviruses are of most concern. The first recorded outbreak of Hanta has been traced back to the Korean War, when more than 2,000 United Nations troops contracted the disease, and many died. The virus, which is now known to reside in field mice inhabiting an ecological niche near the Demilitarised Zone, was later carried aboard ships to the United States where, in 1993, it caused an outbreak that infected 72 people Navajo Indians in the U.S. southwest. All developed extreme breathing difficulties and kidney failure, and more than half died.
The virus then went underground. Since being identified by modern genetic sequencing techniques, virulent outbreaks have been recognised in Greece and the Balkans. A milder form has been found in Scandinavia, large areas of the former Soviet Union, and in sporadic parts of Europe. In South Korea, 13 percent of rats tested in Seoul carried antibodies to the virus, and a global study has since discovered antibodies in rats in North and South America, Australia, other parts of Asia and Europe. A related cousin of the virus has been found in 80 per cent of adult rats tested in Baltimore. Although there have been no known Hanta outbreaks in the east coast of the U.S., some scientists speculate that the virus may be partly responsible for the high level of kidney disease among inner-city residents of Baltimore. One percent of kidney dialysis patients at one Baltimore hospital have also tested positive for Hantavirus antibodies.
Like Ebola and Marburg, no one knows where the Equine morbillivirus discovered in Australia last year came from. But scientists agree that they were extremely lucky that it was not easily transmissible – at least, not in this outbreak. “Once it’s in your body, it’s extremely virulent. Really virulent,” says Dr Allan Gould, a molecular biologist at the Australian Animal Health Laboratory near Melbourne whose genetic sequencing pinned down the viral culprit. “The thing that stopped this from being a major catastrophe is the fact that it’s not very contagious.”
But Gould, along with other scientists interviewed, warns that such viruses are extremely unpredictable. Ebola, Marburg, Hanta, Lassa and Equine morbillivirus are all RNA viruses – viruses that mutate rapidly, because they lack a ‘proofreading’ ability during replication. Each outbreak can represent a different strain, perhaps more deadly or more contagious than its predecessor. A virulent Ebola-like virus, if transmissible over the air such as the Reston strain, but (unlike the Reston strain) is also lethal to humans, could rapidly grow into a global epidemic. HIV, also classed as an emerging virus, was one genie that could not be put back in the bottle once it escaped.
Already, antibodies to variants of Ebola have been detected in monkeys arriving in Western laboratories from Indonesia and the Philippines, and tests in the Philippines have found antibodies in monkey handlers working for researchers in Luzon island, and in the bloodstream of villagers and macaques on Mindanao.
Shortly after the resumption in 1990 of monkey shipments to the Reston laboratory – site of the only recorded U.S. outbreak of Ebola in 1989 – more than 80 per cent of the animals developed Ebola within months of arrival. The infection became so widespread, reaching other unconnected rooms, that all of the laboratory’s animals had to be sacrificed.
Scientists to this day do not know the link between the Ebola variants in Asian monkeys and the prevalence of Ebola in Africa, and still have no idea where the virus resides between outbreaks. While the Reston outbreak suggests the Asian variants may not fatal to humans, no one knows for certain.
“Despite historical projections to the contrary, we remain vulnerable to a wide array of new and resurgent infectious diseases,” Dr David Satcher, director of the Centres for Disease Control and Prevention in Atlanta, said in a 1994 report to the Clinton Administration. “Our anti-microbial drugs have become less effective against many infectious agents. At the same time, our ability to detect, contain and prevent emerging infectious diseases is in jeopardy.”
Increasingly, scientists are talking about the 1990s as the ‘post-antibiotic era.’ Doctors are coming across newly virulent and resistant strains of old diseases, such as tuberculosis, cholera, yellow fever, malaria, dengue fever, diphtheria, pneumonia, gonorrhoea, meningitis and Rift Valley fever. Strains of HIV resistant to existing anti-viral drugs have also arisen recently. And these have not only been found in the developing world: an epidemic of the mosquito-transmitted Dengue fever has broken out in Britain this year, and at least 800 people have been infected. Second-hand tyres imported from developing countries to the United States have carried mosquito larvae, which hatched and recently caused a number of cases, and infections have also been reported in northern Australia.
“Drugs that once seemed invincible are losing their effectiveness,” Satcher warns in his report. “Increased microbial resistance has resulted in prolonged hospitalisations and higher death rates from infections, has required much more expensive, and often more toxic, drugs or drug combinations – even for common infections.”
New diseases have also been appearing: Lyme disease, Legionnaire’s disease, toxic shock syndrome, Hepatitis C, and cryptosporidiosis, a recently identified microbial intestinal parasite that triggered the most widespread waterborne disease outbreak ever seen in the United States. In Milwaukee, Wisconsin, cryptosporidiosis contaminated a municipal water supply and caused 403,000 cases of severe diarrhoea, of which 4,400 required hospitalisation. In early 1993, a recently discovered strain of E. coli bacteria, known as O157:H7, contaminated the meat supplied to a hamburger chain, creating an infection that spread across state boundaries. It triggered bloody diarrhoea and serious kidney disease, and is known to have killed at least four children.
Coupled with the costs of treating HIV, the re-emergence of infectious diseases – due to population growth and concentration, deforestation and rapid geographical movements – has been estimated to cost US$120 billion a year in the United States alone, both in direct medical costs and in lost productivity. Despite the mind-boggling size of these figures, experts believe it is an underestimate.
What can we do? Scientists have been pressuring the politicians to take the problem seriously for more than a decade, since the emergence of the AIDS pandemic scuttled the smugness of a scientific community that had once thought the infectious disease battle largely won. The eradication of smallpox from the face of the planet in 1976 made it seem that humanity could eventually conquer all. The U.S. Surgeon-General even announced in 1969 that modern medicine had done away with the threat of infectious diseases forever.
That type of cocksureness is not to be found in the medical community today. It is a community hunkered down for a major battle, against the legions of new and old diseases that – even without a major global plague – are expected to keep scientists bogged down in microbial guerrilla warfare for decades.
And yet, funding for institutes such as the Centres for Disease Control have been on the wane. The World Health Organisation is meant to care for the Earth’s five billion people with a budget equal to that of a large metropolitan hospital in the United States.
Hopefully, the recent outbreak of Ebola in Zaire will help scare governments into action. There has been some improvements: the United Nations General Assembly only a few years ago held an extraordinary session to consider the AIDS pandemic, the first time the forum had discussed a health issue.
But Mann and others want more than talk, they want action: “A global health approach is needed now to detect as rapidly as possible the next inevitable infectious disease pandemic.”
We may be able to split the atom and send space probes beyond the solar system, but it seems we may never have mastery over the germ world. To quote William H. McNeill, author of the seminal work Plagues and Peoples, “Ingenuity, knowledge, and Organisation alter but cannot cancel humanity’s vulnerability to invasion by parasitic forms of life. Infectious disease, which antedated the emergence of mankind, will last as long as humanity itself, and will surely remain, as it has been hitherto, one of the fundamental parameters and determinants of human history.”