Breakthrough on Detection of Food Parasite

31 March, 2003

A European research team, led by Teagasc scientist Dr Geraldine Duffy, has achieved a world –first in the development of a new method to detect the parasite, Cryptosporidium parvum in food.

The discovery is the culmination of a three-year European-funded research project, which was co-ordinated by Dr Duffy of the Teagasc National Food Centre and involved eight European research groups.

Cryptosporidium parvum is an emerging parasite in food and infected humans can suffer acute diarrhoea with abdominal pain, accompanied by nausea, vomiting and low grade fever. The disease usually lasts up to three weeks but for people with low immunity, it can become chronic and persistent.

The parasite is found in the intestinal tract of cattle and sheep and is excreted in the faeces. It can be transmitted from animal to person, person to person, through ingestion of contaminated water or food or by direct contact with contaminated environmental surfaces.

Using the newly developed detection system, scientists at the Teagasc National Food Centre have carried out the first studies on the prevalence of Cryptosporidium parvum in meat and salads and have also investigated its survival rate in these foods.

“While the parasite was found in some 7% of faecal samples from a sample of almost 300 animals destined for slaughter, it was not detected on any of the carcasses. When meat samples were spiked with the parasite, we have found that freezing reduces infection by 96%. We have also found that cooking of meat kills the parasite,” said Dr Duffy.

Initial investigations by the Teagasc research team of lettuce being sold in retail outlets found no Cryptosporidium parvum. However, when lettuce was spiked with the parasite and stored at refrigeration temperature of 4 degrees C, 50% of the parasites were still viable after one day and 10% were viable after three days.

“The survival of the parasite on refrigerated lettuce is of particular concern if the leaves are not properly washed or may pose a risk of cross contamination of other foodstuffs in the fridge,” said Dr Duffy.

Dr Duffy said that the new detection methods will be of considerable benefit in allowing continued research and monitoring of this emerging parasite in foods.