It seems humans are losing the battle against ever stronger germs. Will our new superdrugs be up to the task of fighting these superbugs?
BY GREG CALLIGARO for YOU Pulse magazine
Imagine this: public places are deserted, empty trains pull in and out of stations and the few passengers who dare brave public transport look around suspiciously from behind surgical masks.
At airports security officials scan incoming passengers with thermal imaging cameras to identify possibly infected people by the telltale infrared glow of fever.
In the suburbs those suspected of having had contact with killer germs are kept under virtual house arrest: quarantined at home under video surveillance and marked with electronic tags to monitor their movements.
A cough or a sniff by a stranger arouses panic – because death is now airborne and it’s all around.
These chilling images sound as if they’re from the latest sci-fi movie – but in fact they’re very real scenarios experienced in Asian cities such as Bangkok and Singapore during the Severe Acute Respiratory Syndrome (Sars) outbreak in 2003.
Originating in China’s Guangdong province this virus sparked worldwide panic, infecting more than 8 000 people and resulting in 774 deaths from Asia to North America.
Yet in many respects we got off lightly: the disease disappeared quietly before it could become a truly global pandemic and by taking rapid action doctors managed to contain the outbreak.
Experts say we may not be so fortunate the next time a killer bug strikes,warning that conditions are right today for the emergence and spread of such a germ.
‘‘A virus lives within a 24-hour plane ride from every city on Earth,’’ Richard Preston writes in his bestselling book The Hot Zone.
‘‘Once it hits the airline network it can go anywhere in a day – Paris, Tokyo, New York, Los Angeles – anywhere where planes fly.’’
Thanks to international jet travel people infected with a disease can carry their inadvertent ‘‘passengers’’ to distant lands – or home to their families – before the first symptoms even start to appear.
New diseases on the rise
But it’s not just the speed of modern-day international travel that has made conditions ripe for a global pandemic. Several other human activities have led to the emergence and spread of new diseases.
The destruction of rainforests and encroachment on wildlife habitats, together with the construction of new villages and housing developments in rural areas, have brought people into contact with a wide range of wild animals – and the previously unknown microbes they carry.
Changes in agriculture, such as the introduction of new crops, has attracted new crop pests and exposed farming communities to previously unknown diseases.
And the rapid growth of cities in many developing countries has resulted in large numbers of people living in crowded areas with poor sanitation. In conditions such as these contagious illnesses have a field day.
Killer germs on the loose
There’s a new spectre when it comes to global diseases: H5N1 influenza, commonly called avian influenza or bird flu. It’s a subtype of the influenza A virus that infects birds but it can also cause disease in humans.
It occurs naturally in many bird populations in Southeast Asia but is now spreading globally, killing tens of millions of birds and resulting in the culling of hundreds of millions more – including domestic poultry – to stem its spread.
So far only humans handling sick birds have become infected but if the virus mutates or reassembles into a strain that can effectively pass from one human to another we could have a global emergency on our hands.
In 2003 world-renowned virologist Robert Webster wrote in a report that ‘‘the world is teetering on the edge of a pandemic that could kill a large fraction of the human population’’. This is no alarmist overreaction: the Spanish Influenza outbreak of 1918-1919, caused by a particularly virulent strain of influenza, is estimated to have killed 25-50 million people.
Deadly Ebola outbreak
And as recently as November last year the deadliest germ known to humankind, the Ebola virus, emerged again in Uganda from its unknown reservoir in the jungles of central Africa, killing nine out of every 10 people it infected.
Death comes painfully: the virus virtually dissolves internalorgans within days, causing bleeding from every pore. There is no known cure.
Why are humans still so vulnerable to infectious disease when we have sophisticated antibiotics and keep hearing about antiviral breakthroughs?
Not long ago doctors thought they’d managed to bring infectious diseases under control for good. Smallpox had been eradicated, effective vaccines had been developed for polio and yellow fever and with the discovery of penicillin and other antibiotics treatment was available forancient illnesses such as syphilis, leprosy and even the bubonic plague of the late Middle Ages.
Diseases such as diphtheria, whooping cough and tetanus seemed to belong to history books. It was only a matter of time, scientists believed, before we’d finally leave behind the dark times when microscopic invaders from an unseen world could threaten our existence.
Louis Pasteur, one of the fathers of the science of microbiology and the inventor of the vaccine for another dreaded virus, rabies, once boasted that one day every infectious disease would be as easy to beat.
Deadly infections threatening
But no one believes that any more. Despite the arsenal of medicines modern science can call upon in its fight against disease, deadly infections are still a threat to everyone everywhere.
Scientists at the Centers for Disease Control and Prevention (CDC) in the US warn that we’ve entered an age where ‘‘the spectrum of infectious diseases is expanding and cases of many infectious diseases once thought to be controlled are increasing’’.
Hardly a week goes by without a report in the media of some kind of outbreak – plague in India, ‘‘flesheating’’ Streptococcus in Britain, drug-resistant Staphylococcus in hospitals in the US, hard-to treat wound infections in soldiers returning from Iraq.
Closer to home we hear of a diarrhoeal epidemic in Delmas in Mpumalanga and an outbreak of a resistant bacterial infection in a neonatal intensive care unit in KwaZulu-Natal.
We also have our own version of Ebola: a virus called Congo-Crimean fever, carried by ticks, which – every few years, sporadically and unpredictably – emerges to kill farm workers in rural areas.
Running out of ammunition
Even the old killer germs – the ones we thought we’d beaten – have learnt to adapt to our fancy medicines. This should come as no surprise: bacteria are after all the most successful organisms on the planet, having adapted over millions of years to every ecological niche from hot sulphuric springs to the deep ocean floor.
Only human arrogance could assume we could wipe them out with our array of chemical weapons in as little as 50 years.
Unfortunately, as Columbia University’s Dr Harold Neu observed in the journal Science, ‘‘Bacteria are cleverer than men.’’ For one thing, we’re hopelessly outnumbered – even our own bodies’ total number of cells are exceeded tenfold by the bacteria that colonise our skin and digestive tract.
The key to their ability to develop resistance to antibiotics is that they can mutate (change their genetic structure). In a person with an active infection each bacterium may replicate as often as every 20 minutes.
With each division mutations develop spontaneously in their DNA and while most of these random reshufflings merely create useless or debilitating traits every now and again they may give a bacterium a survival advantage – such as the ability to pump out drugs from inside their cells or produce enzymes to chew them up.
Streptococcus pneumoniae, the bacterium most often responsible for pneumonia and meningitis (an infection of the membranes lining the brain), is now routinely resistant to penicillin. And the dreaded methicillin-resistant Staphylococcus aureus (MRSA), one of the so-called hospital superbugs, is becoming increasingly resilient to salvage therapy.
Even more alarmingly, these resistant bacteria are breaking out to infect healthy people outside hospital wards.
Antibiotics to blame
The rampant overuse of antibiotics and the prescribing habits of overzealous doctors are largely to blame. A study in the Journal of the American Medical Association found half of patients with a common cold were given antibiotics – even though antibiotics work only against bacteria and a cold is caused by a virus.
The situation is made worse by human behaviour. Patients often don’t follow the instructions when taking antibiotics or stop taking them when their symptoms improve but before the infection has completely cleared up.
And when faced with sub-lethal concentrations of antibiotics the hardier bacteria soon outnumber their more susceptible cousins, encouraging the development of resistant strains.
Raiding the arsenal
In a recent breakthrough against influenza scientists created the antivirals Relenza and Tamiflu, the first effective treatment against the virus.
Since these medicines are also effective against bird flu countries such as the US have been stockpiling vast amounts against a potential pandemic.
Unfortunately it seems the virus is building up resistance – and when a real pandemic strikes we may not have any firing power left in our arsenal.
Antibiotics are also routinely abused by the agricultural sector: livestock farmers add them to feed to promote growth and prevent disease. Resistant bugs then find their way from animals and animal products to humans.
TB sidesteps science
Tuberculosis has also learnt to sidestep science. An unusually tough and slow growingmicrobe, TB is usually treated effectively with a combination of four drugs which are taken together for six months.
If patients are inadequately treated – either because they don’t take the prescribed treatment in the correct way or because low-quality medication is used – so-called multi-drug-resistant TB(MDR-TB) may result.
Although it’s no more contagious than ‘‘normal’’ TB this is an important health issue because treatment is longer and requires more expensive medication.
Recently South Africa has seen the emergence of extensively drug-resistant TB (XDR-TB), which is also resistant to some of the second-line medications. We’re running out of treatment options.
Of course, in South Africa TB has a sinister comrade-in-arms: the human immunodeficiency virus (HIV) which causes Aids. In this partnership an age-old bacterium and a fairly new virus have forged an unholy alliance: almost half of all patients newly diagnosed with TB are also infected with HIV.
Public enemy No 1
HIV/Aids must surely be the infective disease emergency of our generation. The World Health Organisation (WHO) estimates HIV, which was discovered in 1981, has killed more than 25 million people – the majority in sub-Saharan Africa – making it one of the most destructive pandemics in recorded history.
It’s a particularly diabolical virus because, unlike Ebola which can kill in hours, HIV leaves its victims relatively well for several years – with plenty of opportunity to pass it on to others.
So far HIV has resisted all attempts to halt its spread using the usual strategy against viral infections: immunisation. The viral DNA mutates so easily and the proteins that coat the virus are so variable that researchers are still far from developing an effective vaccine.
Immune system under attack
Experts in infectious disease are especially fascinated by HIV because it attacks the one stronghold that normally holds armies of microscopic pests at bay: our immune system.
Infecting and killing battalions of specialised white blood cells called macrophages and lymphocytes, HIV weakens infected patients’ immune systems until they become vulnerable to any attack. The result? A menagerie of opportunistic microbes that a healthy immune system would easily swat away swarm over the body’s defences and cause disease.
Ready, aim, fire!
Far from racing to the rescue the pharmaceutical industry seems to be running out of answers. Some of the biggest companies – Bristol-Myers-Squibb, Eli Lilly, Roche and most recently Bayer – have abandoned research into new antibiotic drugs in favour of more lucrative pursuits.
Just seven new antibiotics have passed clinical trials since the year 2000, compared with 30 in the previous decade.
After the bravado of the previous century we now have new respectfor germs – especially as it seems at the moment they’re winning the war.
The news is not all bad though. Antiretrovirals, although certainly not a cure, have revolutionised the treatment of patients with HIV/Aids, allowing them to strengthen their immune system andlive a virtually normal life.
Search for new therapies
The search for new therapies continues with help coming from unexpected sources. In 2006, after screening 250 000 natural extracts, scientists at Merck Pharmaceuticals published details of anew antibiotic gleaned from a soil sample taken in South Africa.
Called platensimycin it kills many kinds of bacteria – including MRSA – and if it passes clinical trials it will become only the third completely new class of antibiotic developed in the past four decades.
And in the forests of northern Europe researchers have found a small black mushroom that contains the first of what may be a powerful new class of antibiotics and antivirals called defensins (a type of protein that’s active against bacteria and enveloped viruses).
In some ways modern science has never been better equipped to deal with the threat of emerging disease, with better laboratory techniques such as gene sequencing allowing us to identify and diagnose illnesses much earlier.
But as Dr Joe Jarvis, a local infectious disease expert who’s researching a type of fungal meningitis afflicting patients with HIV, points out, ‘‘Preventing a future in which germs are once again widespread killers is going to take more than just inventing new magic bullets.’’
On a global level strategies have to include more rational use of antibiotics in healthcare and agriculture and, of course, improved techniques in developing new medicines.
Public health authorities should remain on high alert to contain outbreaks before they become epidemics. In the developing world, where epidemics of cholera and dysentery are spawned by war, poverty, overcrowding and poor sanitation, the provision of a clean water supply and access to primary healthcare remain of the utmost importance.
Your best defence
On a personal level there’s much we can do to protect ourselves from the germs that cross our path. Condom use and safer sexual practices – strategies that rely on the cooperation of individuals, not scientists or doctors – remain mainstays in the battle against HIV/Aids.
Today a simple measure such as washing your hands is just as important in preventing infections in a hospital from spreading as it was when it was first proposed in the 19th century.
Making sure your children receive all their immunisations is still one of the most effective ways of protecting them against potentially devastating viruses such as measles and polio.
There isn’t necessarily a ‘‘pill for every ill’’ and it’s worth looking at alternative strategies. You can eat spicy foods to help your body fight a cold (chillies contain a natural decongestant), eat cabbage to treat an ulcer (cabbage juice contains a substance called sulforaphane that kills the bacterium Helicobacter pylori which causes 90 per cent of ulcers) or suck zinc lozenges if you have a sore throat (studies have shown zinc boosts the body’s immune system).
Personal hygiene fights germs
Your mother was right. Much of the advice doctors give to avoid infection by household germs is just old-fashioned hygiene – wash your fruit and vegetables, scrub your cutting board after using it for raw meat and use bleach which, despite the slew of fancy cleaning products on supermarket shelves, is still an effective cleaner for just about anything.
But germs are all around us and no matter how hard we try we’ll never be able to completely avoid getting sick.
Our best strategy to combat illness is to keep our immune system in fighting readiness – stress, cigarette smoke, a poor diet and lack of sleep contribute to weaken the immune system and leave us open to infection and make it harder to recover from an illness.
It’s better to take a few precautions and keep yourself healthy than to rush to the doctor: prevention, as always, is better than cure.
How a flu epidemic could hit the world
New Page 1
If the H5N1 bird flu virus mutates and spreads easily from human to human (as is evident from events in Indonesia) and is as deadly as the 1918 flu virus it could lead to the following scenario:
||THE 1918 FLU
|Chief means of transport
Time it takes the virus to
all parts of the globe
|Protective and preventive
||Masks and antiseptic
||Bed rest, aspirin
Antivirals such as
Relenza and Tamiflu
||25 million-50 million
100 million if the new virus
potent and the antivirals
as effective as scientists
(This is an edited version of a story that originally appeared in YOU Pulse / Huisgenoot-POLS magazine, Autumn 2008. Buy the latest copy, on newsstands now, for more fascinating stories from the world of health and wellness.)