WHAT THE RAT BROUGHT IN

There is no cure for a range of bleeding viruses.

Deep Inside a freezer in a high-security laboratory a few miles outside Salisbury lies a family of the world's most deadly viruses. For those infected with any of these viruses there is no cure, no vaccine, and for many people, no hope.

As many as nine out of 10 people attacked by viruses like those stored here in frosted phials will die. Victims bleed to death, the infection attacks vital organs, including the liver, and destroys the blood-clotting mechanism. Vomiting, anorexia, fever and bleeding from gums, nose, lungs, uterus and intestines are all symptoms.

Scientists hunting for a cure for the deadly infections of this family of viral haemorrhagics at the Centre for Applied Microbiology and Research (CAMR) at Porton Down handle them only via robotic arms in air-tight cabinets. Their maximum containment laboratory is one of only six labs around the world which can comply with Grade Four security - the most stringent of WHO conditions involving triple packing and high-security systems that limit movement to within the containment lab.

For millions of people, though, in a growing list of countries, there is no such protection from the mysterious and deadly bleeding viruses which in many cases are carried symbiotically by unknown host rodents. In dozens of countries, the viruses are at large and infecting increasing numbers of people, many of whom have died.

These viral haemorrhagic fevers (VHFs) are mostly named after the area where they claimed their first victims. Ebola, one of the two most potent strains and one of the most hazardous biological agents known to man, was first identified 20 years ago in the synonymous river in Zaire.

Despite knowing the genetic make up of the virus, scientists do not fully understand the various mechanisms by which the infection causes the disease, which can affect the liver or reduce the number of platelets in the blood- clotting system. VHFs can attack blood cells directly, causing vital plasma to escape, and can trick the immune system into delaying the vital production of antibodies needed to ward off the attack.

"VHFs are severe and life-threatening diseases caused by a range of viruses, their key characteristic is that they produce this bleeding ... which causes the severity of the disease and the resultant shock," says Dr Graham Lloyd, head of diagnostics at CAMR. "These viruses ooze mystery and danger and present a major challenge to man's scientific capabilities."

The emergence of many of the VHFs is thought to be linked to environmental changes and ecological disturbances and destruction. Host rodents have been disturbed by man's intrusion into forests or savannahs, or by changing agricultural practices in what were wilderness areas. In parts of South America, for example, clearing of forests has exposed human to viruses carried by animals with which they had not previously come into contact.

An outbreak of Guanarito virus in Venezuela began when a rural community began to clear woodland. It is suspected that the felling work disturbed dust which included dried urine from a species of rat which carries the virus. The virus got directly into the lungs of its victims when they breathed in the contaminated dust.

"This virus came out of nowhere," says Dr Lloyd. "Due to deforestation, man comes into contact with rodents that carry the virus. The rodents themselves are not affected, and the virus only starts causing disease when it jumps the species."

Dr Bernard Le Guenno, director of the Centre for Haemorrhagic Disease at the Pasteur Institute in Paris agrees: "The emergence of these viruses is due to new conditions. The growing population of the world changes the balance of the ecological system. It upsets stable ecosystems and puts man into contact with animals that carry these viruses."

Other kinds of environmental change also can trigger outbreaks. Five years ago in the American Midwest, a combination of exceptionally heavy rainfall and increased groundnut production drew in the deer-mouse which carries a virus that attacks the lung in humans. In Argentina, land cultivation has attracted a huge population of vester mice which carry the Junin virus. And the expansion of reservoirs affects the spread of mosquito-borne viruses.

In a number of cases, including Ebola and the equally deadly Marburg, the host of the virus has not been tracked down despite extensive research. But in other instances where humans have contracted the disease from monkeys, the monkey seems to be just as much a victim as man.

There is no cure in sight for VHFs and concern is growing in the West for the health of tourists. The incidence of VHFs in Africa, South America and the Far East has been growing and there are increasing fears that tourism to those areas will eventually bring the viruses to Europe. Scientists at CAMR and colleagues in the Public Health Laboratory Service now operate a 24-hour hotline for doctors in the UK to check the symptoms of patients who may have the diseases.

"We thought Ebola was confined to Zaire and Sudan where it was first discovered, but in the last few years we have had a bit of a shock because it was found in primates from the Philippines," says Dr Lloyd. "That taught us not to be complacent.

"People have to be on their guard. There is always the possibility that if you have a large tourist population moving around and going to places that have not traditionally been open to tourism, someone is going to bring the virus back. We have to be vigilant about spotting it."

The ideal would be to have a vaccine and to be able at least to advise travellers on what to avoid, but there is no immunisation available and in many cases the host of the virus is unknown. As Dr Lloyd says, "In the case of Ebola and a number of other viruses we don't know what carries it. We don't know why it suddenly disappears and then comes back. If you know the answers to these sorts of things you can do something about them. The fact is, we don't know, and that's frightening." !

EMERGING & RE-EMERGING VHFs

SIN NOMBRE: First reported in 1993 when two young people died of respiratory problems in New Mexico. Cases then found in Colorado and Nevada. Virus invades blood cells in the lungs.

BRAZILIAN SABIA: Fatality rate 15 to 30 per cent. Three incidents since 1990. Death is usually the result of haemorrhaging and jaundice.

GUANARITO: In 1990, an outbreak in Venezuela affected 104 people of whom 26 died. Cotton and cane rats are likely hosts.

MACHUPO CIRUS: Three years ago nine cases were reported in Bolivia. Seven died.

JUNIN: First found in corn harvested in Argentina. The host appears to be a rodent. Major research programme underway to find vaccine.

KYANANUR FOREST DISEASE AND OMSK FEVER: Affects central nervous system, causes bleeding from vital organs over days before death.

DENGUE: Mosquito-borne. Life-threatening, particularly among young children.

CRIMEAN-CONGO FEVER: Reported fatality rate of up to 50 per cent. Host carriers: hares, birds and a species of tic. No vaccine.

EBOLA: Cause of the most severe and lethal haemorrhagic illnesses known. First documented in 1976 when 280 died in Yambuku, Zaire. Last year 190 died in an outbreak in Kitwit, Zaire. In reported outbreaks since 1976, the death rate was 82 to 90 per cent. Total death toll to date estimated at around 800. Host unknown.

HANTAVIRUS: Carried by rodents. New lethal form found in south-western USA.

MARBURG: Similar to Ebola but with 25 per cent death rate. Host unknown.

RIFT VALLEY FEVER: Mosquito-borne. Cause of the most explosive epidemics seen in Africa.

Have you tried new the Independent Digital Edition apps?
Arts and Entertainment

ebooksNow available in paperback
Arts and Entertainment

ebooks
Arts and Entertainment
Feeling all at sea: Barbara's 18-year-old son came under the influence of a Canadian libertarian preacher – and she had to fight to win him back
TV review
Arts and Entertainment
Living the high life: Anne Robinson enjoys some skip-surfed soup
TV review
Arts and Entertainment

Great British Bake Off
Arts and Entertainment
Doctor Who and Missy in the Doctor Who series 8 finale

TV
Arts and Entertainment

film
Arts and Entertainment
Chvrches lead singer Lauren Mayberry in the band's new video 'Leave a Trace'

music
Arts and Entertainment

music
Arts and Entertainment
Home on the raunch: George Bisset (Aneurin Barnard), Lady Seymour Worsley (Natalie Dormer) and Richard Worsley (Shaun Evans)

TV review
Arts and Entertainment

TV
Arts and Entertainment
Strictly Come Dancing was watched by 6.9m viewers

Strictly
Arts and Entertainment
NWA biopic Straight Outta Compton

film
Arts and Entertainment
Natalie Dormer as Margaery Tyrell and Lena Headey as Cersei Lannister in Game of Thrones

Game of Thrones
Arts and Entertainment
New book 'The Rabbit Who Wants To Fall Asleep' by Carl-Johan Forssen Ehrlin

books
Arts and Entertainment
Calvi is not afraid of exploring the deep stuff: loneliness, anxiety, identity, reinvention
music
Arts and Entertainment
Edinburgh solo performers Neil James and Jessica Sherr
comedy
Arts and Entertainment
If a deal to buy tBeats, founded by hip-hop star Dr Dre (pictured) and music producer Jimmy Iovine went through, it would be Apple’s biggest ever acquisition

album review
Arts and Entertainment
Paloma Faith is joining The Voice as a new coach

TV
Arts and Entertainment
Dowton Abbey has been pulling in 'telly tourists', who are visiting Highclere House in Berkshire

TV
Arts and Entertainment

TV
Arts and Entertainment
Patriot games: Vic Reeves featured in ‘Very British Problems’
TV review
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
SPONSORED FEATURES

ES Rentals

    Independent Dating
    and  

    By clicking 'Search' you
    are agreeing to our
    Terms of Use.

    Refugee crisis: David Cameron lowered the flag for the dead king of Saudi Arabia - will he do the same honour for little Aylan Kurdi?

    Cameron lowered the flag for the dead king of Saudi Arabia...

    But will he do the same honour for little Aylan Kurdi, asks Robert Fisk
    Our leaders lack courage in this refugee crisis. We are shamed by our European neighbours

    Our leaders lack courage in this refugee crisis. We are shamed by our European neighbours

    Humanity must be at the heart of politics, says Jeremy Corbyn
    Joe Biden's 'tease tour': Could the US Vice-President be testing the water for a presidential run?

    Joe Biden's 'tease tour'

    Could the US Vice-President be testing the water for a presidential run?
    Britain's 24-hour culture: With the 'leisured society' a distant dream we're working longer and less regular hours than ever

    Britain's 24-hour culture

    With the 'leisured society' a distant dream we're working longer and less regular hours than ever
    Diplomacy board game: Treachery is the way to win - which makes it just like the real thing

    The addictive nature of Diplomacy

    Bullying, betrayal, aggression – it may be just a board game, but the family that plays Diplomacy may never look at each other in the same way again
    Lady Chatterley's Lover: Racy underwear for fans of DH Lawrence's equally racy tome

    Fashion: Ooh, Lady Chatterley!

    Take inspiration from DH Lawrence's racy tome with equally racy underwear
    8 best children's clocks

    Tick-tock: 8 best children's clocks

    Whether you’re teaching them to tell the time or putting the finishing touches to a nursery, there’s a ticker for that
    Charlie Austin: Queens Park Rangers striker says ‘If the move is not right, I’m not going’

    Charlie Austin: ‘If the move is not right, I’m not going’

    After hitting 18 goals in the Premier League last season, the QPR striker was the great non-deal of transfer deadline day. But he says he'd preferred another shot at promotion
    Isis profits from destruction of antiquities by selling relics to dealers - and then blowing up the buildings they come from to conceal the evidence of looting

    How Isis profits from destruction of antiquities

    Robert Fisk on the terrorist group's manipulation of the market to increase the price of artefacts
    Labour leadership: Andy Burnham urges Jeremy Corbyn voters to think again in last-minute plea

    'If we lose touch we’ll end up with two decades of the Tories'

    In an exclusive interview, Andy Burnham urges Jeremy Corbyn voters to think again in last-minute plea
    Tunisia fears its Arab Spring could be reversed as the new regime becomes as intolerant of dissent as its predecessor

    The Arab Spring reversed

    Tunisian protesters fear that a new law will whitewash corrupt businessmen and officials, but they are finding that the new regime is becoming as intolerant of dissent as its predecessor
    King Arthur: Legendary figure was real and lived most of his life in Strathclyde, academic claims

    Academic claims King Arthur was real - and reveals where he lived

    Dr Andrew Breeze says the legendary figure did exist – but was a general, not a king
    Who is Oliver Bonas and how has he captured middle-class hearts?

    Who is Oliver Bonas?

    It's the first high-street store to pay its staff the living wage, and it saw out the recession in style
    Earth has 'lost more than half its trees' since humans first started cutting them down

    Axe-wielding Man fells half the world’s trees – leaving us just 422 each

    However, the number of trees may be eight times higher than previously thought
    60 years of Scalextric: Model cars are now stuffed with as much tech as real ones

    60 years of Scalextric

    Model cars are now stuffed with as much tech as real ones