Time lapse makes tracing E. coli 'very difficult': WHO
Tracing the path of the lethal E. coli outbreak back to its source is difficult because of the time elapsed between contamination and testing, a World Health Organisation expert said Tuesday.
"Often such an outbreak is caused by a single batch of produce and by the time you get to sampling, the batch is out of the system," Guenael Rodier, who is in charge of communicable diseases at the WHO's Europe division, told AFP.
"It is very difficult to find the culprit for such an outbreak ... What we have to do with a food-borne infection such as this, is to find the epidemiological link between various cases in an outbreak. That is not an easy thing to do, and there are many authorities involved," he said.
Tracking the bacteria was complicated by the fact that contaminated people often had trouble remembering exactly where and what they had eaten by the time they were questioned after the incubation period of around five days.
"Once we believe we have found an epidemiological lead that we have good reason to suspect, it is then a question of going through the food chain. But since you are going through the food chain at a time rather late in the course of the event, your samples may come out negative," he explained.
Enterohaemorrhagic E. coli (EHEC) can cause bloody diarrhoea and potentially fatal liver damage, as well as full-blown haemolytic uraemic syndrome (HUS), a serious kidney ailment.
The death toll of the bacteria outbreak hit 25 on Tuesday.
All but one of the deaths reported since mid-May have occurred in Germany. The other fatality was a woman in Sweden who had recently returned from Germany.
Authorities are yet to identify the source of the outbreak, which has left more than 2,300 people ill in at least 14 countries. German consumers are advised to avoid raw sprouts, cucumbers, tomatoes and lettuce.
© 2011 AFP