Science Interviews

Kitchen Science - Plague Outbreak!

Ben - For this week’s kitchen science I have come along to the Royal College of Pathologists in London to join a team from the Natural History Museum to tackle an outbreak of infectious disease. Not a real one, you’ll be pleased to hear, but an opportunity to see the real-life techniques used in this sort of situation. The first we heard about the outbreak was on the news.

News Anchor - We’re here in central London at the site of what maybe the origin of a serious disease that has so far left several workmen critically ill in hospital and claimed the life of another. Building has disturbed a previously unknown medieval vault. Four days ago workmen unearthed this vault during routine excavation as part of the central London regeneration programme. Those involved are now critically ill in the London hospital of infectious diseases with one fatality already reported.

Ben - The workmen had stumbled across an ancient vault but it had a much more recent corpse inside. To find out what had happened to the corpse in the vault and give us clues as to what could be wrong with the workmen Dr Nicky Cohen took me through the results of an autopsy.

Nicky - So we have a body in front of us and looking at him we can see that he’s got some blood around his mouth and his eyes. He’s got blackened toes and fingers. That blood picture is making me thing he’s got a blood clotting disorder. On top of that he’s got some insect bites around his ankles. He’s got a swelling on the side of his neck. I don’t know what it is, I’ll take a sample of it later. Putting that together with the insect bites and the rats that we know were in the crypt I’m concerned that he’s got an infection and he’s died of an infection which would fit with the live bodies. The patients in the hospital. As to what causes this I think it’s difficult and I don’t know but I guess something like mumps is an infection that can produce swollen glands in your neck but not many people die of mumps, of course. We know there were rats involved so leptospirosis, Weil’s disease might give us something similar to that and that can cause blood clotting disorders. In terms of putting that altogether with the lumps in the neck what I’m most concerned about is Yersinia pestis which is plague and we need to do some tests to find out what it is.

Ben - by looking at the sample taken from the swelling in the neck under a microscope we were able to confirm the worst. The swelling contained Yersinia pestis bacteria, the plague. There are two stages of plague infection: bubonic and pneumonic. Bubonic plague causes the distinctive swellings on the body or buboes but is transmitted from one person to another through a vector, in this case, fleas. Most people think of plague as a medieval disease, long-since wiped out. But Martin Hall, and etymologist at the Natural History Museum explains how outbreaks of plague still happen today.

Martin - Plague is found naturally in rodents in places like South East Asia, South America, Africa. There are wild rodents that have plague naturally in them. They actually don’t really suffer. They don’t die from the disease. They’re acting as what we call, reservoir hosts. They just maintain the disease. Now and again something happens to break that cycle. There might be a big outbreak of rates and those rats become infested with the plague and these domestic rats are much more susceptible to plague and they can die. When they die the fleas that were feeding on them don’t have anything to feed on so they go looking for something else to eat. They may land on you and bite. Then the bubonic plague is transmitted to you. It seems that the corpse in the vault contracted the plague and then died in the vault. The fleas living on the rats in the vault picked up the bacteria and passed it on to the workmen when they discovered the vault. Bubonic plague is treatable with antibiotics but if this outbreak continues the plague could progress to become the pneumonic form which is spread through the air and has a 90% fatality rate. The clock is ticking for us to take control of the outbreak before this happens. This is where I need your help. What should we do to contain the outbreak and avoid a national epidemic of plague? I asked a few other amateur pathologists who had come along for the event.

“We’ll kill every rat we see”

“You need to let all of the police know in the area so they can notify those who are in charge of communicable diseases”

“We said to trap the rats and then poison them. But then you’re saying about the fleas – maybe burn the rats and that will get rid of the fleas. Then we can quarantine anyone that has symptoms.”

Ben - So what steps do you think we should take to quarantine an outbreak of plague? Can all the rats shut down the underground? Quarantine central London perhaps?

Ben - So far we’ve been faced with the very real possibility of an outbreak of plague in London and asked what would be the best things to do to try and contain it. At the Royal College of Pathologists we decided to kill as many rats as possible and use pesticides to control the fleas, quarantine the affected and call the Health Protection Agency. Dr Tim Wreggitt who is from the HPA and Addenbrooke’s hospital explained what he thought of our containment techniques starting with killing of the rats.

Tim - The idea is that you can’t control rats and you can’t get rid of fleas but the more you reduce the population the lower you make the risk. You can’t eliminate them you try everything you can to reduce the number in a particular area. Quarantine the infected area, that’s really important. You need to know where the new cases are. This is where this is a really good thing – tell health professionals. I think that’s one of the most important things you’ve got round here. This is a very rare disease, very few medical people in this country will have seen a case of plague because it doesn’t occur in this country. You’ve only got the odd case that may come in as an imported disease. Most people couldn’t recognise it if it was their neighbour and so they need to be told what the symptoms are. You need extensive health programme to educate health professionals and to alert the Health Protection unit about these cases. Then you can find, those cases, isolate them and something you haven’t mentioned is giving antibiotics because this is a disease which is controlled by antibiotics if you give it within 24hrs after people get symptoms. Finding the people really quickly with the relevant symptoms, giving them early treatment with cibrofloxacin or something like that will make the mortality go down from 60% to less than five percent. It’s really important. Also those people who have been exposed to cases, if you give them prophylactic antibiotics by which I mean as soon as they’ve been exposed to the risk you then give them antibiotics to prevent them getting the infection. That’s really important as well.

Ben - So we were right to quarantine the area, call in the experts and start trying to control the vector but because we didn’t think of prophylactic antibiotics the mortality rate would have been higher than it should be. The real question is did we do enough to contain the outbreak? To find out we have to go back to the news.

News Anchor - We return now once more to the scene where several weeks ago, we reported on the mysterious illness that had affected several workmen and tragically claimed the life of another. We’re joined by Amy Stevens from the Health Protection Agency. Amy, can you tell us a bit more about the strategy and measures you used to stop this disease in its tracks?

Amy - Following extensive analysis we were able to identify that the bacteria was Yersinia pestis, better known as the plague. Thankfully today this is a disease that is easily and effectively treated with antibiotics. Infected individuals from the area and from the worksites were quarantined and treated and were kept under constant surveillance until it was shown they were clear of infection. It is now completely absent from the site. We consider it to be successfully contained.

News Anchor - That’s great news. Thank you, Amy

Ben - So the measures we put into place were enough to contain the disease and avoid a major outbreak. If you thought of the same sorts of things well done! You’re the kind of person we need around if there’s ever an outbreak of plague.

November 2008