Cyclospora, Toxoplasma and Cryptosporidium have been detected in berries sold in Norway.
The researchers said the results show the need for a system to ensure the parasitological safety of fresh berries.
Blueberries, strawberries and raspberries were tested for Echinococcus multilocularis, Toxoplasma gondii, Cyclospora cayetanensis and Cryptosporidium.
Raspberries were the most contaminated followed by strawberries and blueberries. Strawberries and raspberries were mainly contaminated with Cryptosporidium, while blueberries were mainly contaminated with Cyclospora. Toxoplasma and Cyclospora were frequently found in raspberries, according to the study published in the journal Food Microbiology.
Crypto is the main contaminant
A total of 820 berry samples were analyzed between August 2019 and November 2020. Toxoplasma gondii was detected in 24 samples, Cyclospora in 52 tests and Cryptosporidium in 68 samples. Echinococcus multilocularis was not found.
However, the researchers said it was important to note that only DNA was detected, so there is no certainty that the intact infectious stages of the parasites were present, and there is no information on the viability.
Parasites are rarely detected in foods epidemiologically linked to outbreaks or cases. This often reflects the relatively long periods between infection, symptoms and diagnosis, as well as the relatively short shelf life of the products involved. These two factors make tracing efforts difficult.
Prior risk ranking and source attribution of foodborne and waterborne pathogens in Norway showed that Toxoplasma gondii and Echinococcus multilocularis were among the top three, with Cryptosporidium being ranked ninth among the 20 considered pathogens.
Sources of berries
In Norway, due to the short growing season, many berries come from abroad, with more than 13,000 tons imported in 2020. A total of 86 berry samples were from domestic fruits while others were from other countries. such as Peru, Morocco, Chile, the Netherlands, Portugal and Poland.
Sources of berries contaminated with Toxoplasma included Chile, Poland, Norway and Zimbabwe. Toxoplasma and Cyclospora have been detected on berries imported from Portugal, Morocco, Belgium and the Netherlands.
There was a relatively high occurrence of Toxoplasma-positive raspberry samples imported from Portugal, which the scientists believe may indicate the need to investigate the chain from farm to shipment.
Positive Cryptosporidium samples were found in produce from 11 countries, but the highest frequency was in Norwegian strawberries.
The researchers said that although the findings raise some concern for Norwegian food safety authorities, encouraging consumers to wash the berries before consuming them could reduce the risk of infection. People are already being advised to boil imported frozen berries for a minute before eating them to kill viruses, such as hepatitis A, which can survive freezing temperatures.
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