Catching New Viruses

14 December 2008

Interview with

Professor Robert Swanepoel, National Institute for Communicable Dieases, South Africa

Chris - Hello, Bob.

Bob - Hello, there.

Chris - Welcome to the Naked Scientists. Tell us what happened with this case. Tell us about this history.

Bob - Well this is a travel agent, a 36-year-old lady who worked in Lusaka. Unfortunately shortly after she got ill - you know the beginning of diseases is always milder than what comes later - she went from Lusaka down to a wedding in South Africa and then went back because there was some confusion as to about whether she actually picked up the infection in South Africa or Lusaka.

Chris - What were the symptoms she was complaining of?

Lassa virus, an Arena virusBob - Initially, I mean with any of these things if you're talking about Ebola or severe diseases, people start off with non-specific pain. The same way flu starts with headache and muscle pain and just not feeling well and fever and rigour. That was how she started. She was taking pills for headache and that sort of thing. She went down to the wedding in South Africa and she returned on Sunday evening. From the Monday she was feeling extremely ill and couldn't go back to work at all. She saw several doctors in town and by the Friday she was medically evacuated to South Africa and the following day she died.

Chris - What was the cause of death?

Bob - At that stage what normally happens is that people who are extremely ill, whether it be Ebola or anything else, the infection's really similar to anything with bacterial infection or so-called septicaemia. It could be meningococcal septicaemia so a very similar picture. Clinically the clinicians do the right thing. They pump them full of antibiotics to save their life but the trouble is then if you do a blood culture to diagnose the illness you're not going to find the answer because there's always antibiotics. People die of one illness like that in every city every day. They have this septicaemia and so there was nothing that was deemed to be unusual about it. She was deemed to be a bacterial septicaemia and she died and no results were obtained.

Chris - So how did you find out it was something unusual?

Bob - It was only some days later, two weeks later, when a paramedic who'd flown down in the air ambulance with her came down with the same symptoms and was also medically evacuated. People put two and two together and realised there was something unusual and that's often the case. Talking about emerging diseases earlier in this programme, quite often people can have an emerging disease and a one-off like that you don't notice. It's only with accumulated evidence. When the second person came down and that person developed the same symptoms and it happened to be at the same hospital a day later. The physician recognised this looked identical to the first one.

Chris - Can you tell us what the actual organism was that they were suffering from and where it came from?

Rattus norvegicus, the Brown Rat.Bob - Well this whole group of organisms are known to be associated with rodents. They cause chronic infection in rats and mice of various species. Each of these viruses tends to be associated with a particular rat or rodent species.

Chris - How do you think the lady got it from the rat?

Bob - That's a big question yet to be answered. One of the things is there was a lot of confusion initially. Did she become sick in Zambia or South Africa? We believe it was Zambia and one of the things that has been suggested is an increase in wheat farming. It's not that is just more has been planted per acreage because the price has gone up. That's the sort of thing that happens in nature with human intervention, that we create a bonus situation for rats and mice. With all this wheat around them, grain crops, there's a population explosion. Maybe that had something to do with it because she lived on the edge of town and indeed worked on the edge of town.

Chris - Can you tell us briefly what can you do about this in the future and what's the likelihood of it recurring?

Bob - Well, I suspect it will recur and suggest that we will be better geared-up next time to recognise it. I think even in Zambia the physicians are really good at knowing what to look for.

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