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Escherichia coli | e-coli o157

The Sunday Times

Matthew and the burger bug

By this time, the investigation of the Morecambe cluster had enlisted the big guns of science. As Telford's technicians confirmed each case as an O157 infection, a sample was posted to the government's Central Public Health Laboratory in Colindale, north London, and an e-mail was fired weekly to the Communicable Disease Surveillance Centre, which is based at the same site. The central laboratory, which was founded in 1946, has an annual budget of £10m and employs some 400 staff. It is the nerve centre for tackling infectious diseases, such as Aids, tuberculosis and meningitis.

The lab's scientists have published cutting-edge research on E-colis of every description. The core of these bacteria are minute tube-like cells, which have been classified through proteins in their skin (so-called "O" antigens) into 173 different sorts. Radiating from these cells are little tails, or flagella, which in turn are classified by another antigen ("H"), of which 55 have so far been found. Going a stage further, the O157:H7 organism, involved in the recent British outbreaks, has been sorted into around 80 different types, and the most modern technologies can go even deeper and fingerprint its DNA into thousands of individual strains.

Compared with other infectious agents, O157:H7 is not that common, but it is causing anxiety among scientists because it is incomparably nastier than most. It is astonishingly resilient: able to live in the kind of conditions that would kill other bugs. On farmland, it can survive in the soil for up to six months, while in kitchens it can cling to cool, dry surfaces and shrug off many household cleaners. Unlike infections such as salmonella and campylobacter, which require millions of bacteria to cause human sickness, as few as a dozen of the new E-coli are needed. And when it strikes old people, or children of Matthew's age, it can leave them in a critical state.

Rachael's sons' samples, along with the other children's, were sent to Colindale for what is called "phage typing", which can give clues for investigating outbreaks. Using a handle-cranked contraption on a second-floor laboratory bench, technicians stamp dishes of E-coli with 16 viruses which attack bacteria. By later reading which viruses attacked what, the organism in the dish is given a rough-and-ready type. In the Lanarkshire outbreak, for example, where cross-contaminated ham had been sold by the local butcher, Scotland's equivalent lab, at Aberdeen, identified each patient's specimen as containing a type 2 E-coli bug.

But Colindale's typing of the Morecambe cluster produced a startling result. Matthew's and Tom's specimens, along with the 11-year-old boy's, came up as type 2. The six-year old girl's, however, was typed 8. The girl aged 14 months who had been abroad was apparently infected by type 34. And there was a 21 and a 32 as well. Since an outbreak should involve bugs of the same type, it seemed that, whatever the source of Rachael's sons' infection, it was not the same as all of the others, despite the links of place, time and age. It looked as if the cluster was only a bizarre coincidence.

The environmental health officers took this as good news: there was no Lanarkshire-style outbreak on their patch. Brownjohn and Mann felt that nothing further would be gained by carrying out any more inquiries. No food or other samples were taken from Rachael's home. The nearby allotment, where the children picked apples, was not investigated for infected manure. And, although both she and her boys regularly mixed with other children and parents, no contact-tracing was done to check the possibility of person-to-person spread. Even in the face of Matthew's deteriorating condition, the investigation was brought to an close.

But, far from being grounds for confidence, the hidden story of the Morecambe cluster may have been more disturbing than even the Scottish crisis. It is hardly credible that an infection judged to be so rare that doctors, laboratory staff and environmental health officers give it scant attention should strike eight children in one place and at the same time without any explanation. It is possible that either the phage typing was wrong - and insiders say it often is - or, if they were infected with different types, then that suggests there is more E-coli around than has so far been acknowledged. In short, that Morecambe was the tip of some iceberg of hidden, unreported, infections.

The clue that there may have been more to know is found in statistics compiled at Colindale by the Communicable Disease Surveillance Centre. During the week that Matthew became ill, these showed a dramatic and unexplained leap in O157 reports. In the week before the first day of his illness there were 24 notifications in England and Wales - more or less last year's weekly average. In the week beginning the Monday after, Day 8, during which he was admitted to hospital as an emergency, there were more: 52 reports. But during the seven days between - the week ending September 19 1997 - the numbers pouring in from labs such as Telford's totalled a staggering 103.

What this spike in the graph points to may have been a national outbreak which was not so connected by geographic location to come to local authorities' attention. With foodstuffs often transported hundreds of miles from central processors and packagers, Rachael's boys may have been connected to many others by exactly the kind of "low-level contamination" which the Morecambe investigators had suspected. "We felt we were seeing a local aspect to a national problem," says a member of the local team. "Intuitively, we felt that was the best bet."

A review of the evidence stacked up so far supports this intuition. Most infections in healthy adults produce no or only minor symptoms. Most hospital labs do not routinely test for E-coli, so its true incidence is unknown. No statistics are compiled on e coli-related disease. And the number of deaths cannot be calculated because certificates rarely cite the infection. With the bug's resilience and ability to trigger illness in extreme low doses, it could easily have got into a mass-market product last year, been distributed throughout the UK during September and caused apparently unconnected sickness in children from Land's End to John O'Groats.

If Matthew was the victim of such events, the central laboratory could expose the fact. But again the child was let down by a system that undervalues the E-coli threat. Although Colindale's phage typing sounds impressive and is carried out on all samples received at public health laboratory's labs, it is a cheap, quick, crude and virtually clapped-out technology, devised half a century ago to classify salmonella. More than one third of all O157 strains are lumped together in this system as type 2 - far too big a group to track through the food chain. And although the more sophisticated DNA fingerprinting technique is available at Colindale, it is not routinely used, on grounds of cost.

Once more it was question of the priority for E-coli - and whether the specialists and authorities that are charged with fighting it are doing everything that the public would expect. "Everybody has limited funds," says Tom Cheasty, a senior researcher at the central laboratory. "The way we are financed and staffed, we couldn't do all the work that would be needed to be done on everything. We wouldn't have enough hours in the day. If people spent more time looking at this bug they would have to spend less time looking at some of the others."

But the new fingerprinting technique (called "pulsed-field gel electrophoresis") could have analysed the DNA in Matthew's and Tom's samples and not only matched the precise strain of the organism present against the other Morecambe children's, but also against those involved in all of the other infections reported to north London that week. Each family affected could have been interviewed as Rachael was and common sources readily identified, wherever in Britain they might be.

To fingerprint all of that week's 103 samples might take a technician three months and cost £6000, but such DNA testing combined with new methods of detecting the organism in foodstuffs and bar-code tracing of products through the food chain, could transform the response to E-coli. Not only could rogue producers or packagers be nailed, but also bad practices at abattoirs, dangerous activities such as spraying animal remains and cattle faeces on farmland, and the continued sale of high-risk milk, could all be swiftly tackled. Some scientists believe there would be the long-term chance of eliminating the bug altogether.

Although Colindale cites the pressure of other work, the main beneficiaries of not using the new technologies may not be other research priorities, but the giant food and farming enterprises whose lapses may remain undetected. If tests linked disparate cases of illness such as the Morecambe victims' with batches of common products, such as, say, ham or milk, public opinion could force severe government action, as it did over BSE. And after the wholesale slaughter of cattle brought about by inquiries into two dozen human deaths from new variant CJD, business could be forced into another round of costly remedies to clean up its act.

But if the winner is business, the loser is the consumer - leaving parents such as Rachael to think that illness must be due to something in the home. On the day that Brownjohn called and interviewed her, the things that stuck in her mind most strongly were questions about her habits. Which shelf in the refrigerator do you put cooked meats on? Do you always clean knives after cutting? Could you show me, please, how you wash your hands? Let me look at the kitchen again.

Brownjohn left her thinking that she was to blame for the state of her little boy's health.


Escherichia coli | e-coli o157
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