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Parasites in Imported Fresh Leafy Herbs - April 1, 2017 to March 31, 2022

Food microbiology – Targeted surveys – Final report

Summary

A targeted surveyFootnote 1 analysed 1730 samples of imported fresh leafy herbs over a 5-year period from April 1, 2017 to March 31, 2022. All samples were tested for the presence of Cyclospora cayetanensis (C. cayetanensis) while 1173 samples were also tested for Cryptosporidum species (spp.) and Toxoplasma gondii (T. gondii).

99.8% of the samples tested were found to be satisfactory. Cryptosporidium spp. and T. gondii were not found in any samples. C. cayetanensis was found in 4 of the 1730 (0.2%) samples. The Canadian Food Inspection Agency (CFIA) conducted appropriate follow-up activities. There were no reported illnesses related to these products.

Overall, our survey results indicate that imported fresh leafy herbs sold in Canada are generally safe for consumption, however they can occasionally be contaminated. Consequently, as with all foods, and especially with those that are consumed raw, good hygienic practices are recommended for producers, retailers, and consumers.

Why was this survey conducted

The survey was conducted to provide enhanced oversight of the safety of imported fresh leafy herbs sold at retail in Canada. While fresh leafy herbs are popular among CanadiansFootnote 2, they have unfortunately been associated with recallsFootnote 3 and foodborne illness outbreaksFootnote 4, Footnote 5.

Fresh produce, including leafy herbs can be contaminated with parasites through contact with human and animal waste at any step in the food supply chain such as during production, harvest, post-harvest handling, packaging, distribution, and/or at retail. Unlike bacteria, parasites are unable to grow on foods, however they can remain viable for extended periods of time and may cause illness when ingested. Therefore the presence of parasites on fresh leafy herbs is of concern as they are a commonly consumed by Canadians and are generally consumed raw.

When was the survey conducted

The survey is ongoing, however the results reported herein are for samples collected over a 5-year period from April 1, 2017 to March 31, 2022.

Where were the samples collected from

Samples were collected from national retail chains and local/regional grocery stores located in the following 11 major cities across Canada:

  • Halifax
  • Moncton or Saint John
  • Quebec City
  • Montreal
  • Toronto
  • Ottawa
  • Vancouver
  • Victoria or Kelowna
  • Calgary
  • Saskatoon
  • Winnipeg

The planned number of samples to be collected from each city was based on the population of the province in which the city was located relative to the total population of Canada.

How many and what kind of samples were collected

A total of 1730 imported fresh leafy herbs were collected. Wherever possible, pre-packaged samples were collected. Throughout all 5 years of the survey, the scope of sampling included parsley, cilantro, dill, basil, mint, and chives. Sage, thyme, oregano, tarragon, savoury, and marjoram were also sampled, however sampling of these herbs were limited to the first 3 years of the survey. Samples were collected throughout the year, however a higher proportion was sampled during the months of April to October to reflect the seasonality of foodborne parasitic infections in endemic countriesFootnote 6, Footnote 7, Footnote 8, imports into Canada, and reported cases of cyclosporiasis in Canada. During the first 2 years of the survey, all sample types were randomly collected throughout the year. During year 3 of the survey, cilantro accounted for half of the samples collected. During years 4 and 5, cilantro and basil accounted for a third each of the samples collected. Both basilFootnote 8, Footnote 9 and cilantroFootnote 9 have been frequently associated with cyclosporiasis. A sample consisted of a single or multiple consumer sized packages of the same lot weighing at least 100g.

What were the samples tested for

All 1730 samples were tested for C. cayetanensis. Of the 1730 samples, 1173 were also analysed for Cryptosporidum spp., and T. gondii.

What methods were used to test the samples

Samples were analyzed using methods that detect the presence of deoxyribonucleic acid (DNA) of C. cayentanensis, Cryptosporidum spp., and T. gondii.

How were the samples assessed

There are currently no Canadian standards regarding the presence ofparasites in fresh produce. As the analytical methods used in this survey can only determine the presence or absence of parasite DNA, they cannot discriminate between living (infectious) and dead (non-infectious) parasites. Therefore, the detection of parasite DNA was assessed as "investigative" and required further consideration to determine appropriate follow-up actions.

Table 1 – Assessment criteria
Parasite Satisfactory Investigative
C. cayetanensis Not detected Detected
Cryptosporidium spp. Not detected Detected
T. gondii Not detected Detected

What were the survey results

Cryptosporidium spp. and T. gondii DNA were not found in any samples. C. cayentanensis DNA was found in 4 of the 1730 (0.2%) samples.

Table 2 – Assessment results
Parasite Number of samples tested Satisfactory (%) Investigative (%)
C. cayetanensis 1730 1726 4
Cryptosporidium sppTable note a 0
T. gondiiTable note a 0
Total 1730 1726 (99.8) 4 (0.2)

Survey results are also presented by production practice (table 3), origin (table 4), product type (table 5), and season sampled (table 6).

Table 3 – Assessment results by production practice
Production practice Number of samples tested (%) Satisfactory Investigative
Conventional 1440 (83.2) 1438 2
Organic 290 (16.8) 288 2
Total 1730 1726 4
Table 4 – Assessment results by product origin
Product origin Number of samples tested (%) Satisfactory Investigative
China 2 (0.1) 2 0
Colombia 141 (8.2) 139 2
Costa Rica 1 (0.06) 1 0
Dominican Republic 143 (8.3) 143 0
Ecuador 7 (0.4) 7 0
Ethiopia 7 (0.4) 7 0
Israel 136 (7.9) 136 0
Jamaica 13 (0.8) 13 0
Mayotte 1 (0.06) 1 0
Mexico 376 (21.7) 376 0
Morocco 12 (0.7) 12 0
Peru 36 (2.1) 36 0
Thailand 2 (0.1) 2 0
United States 788 (45.6) 786 2
United States and Mexico 10 (0.6) 10 0
Vietnam 54 (3.1) 54 0
UnknownTable note b 1 (0.06) 1 0
Total 1730 1726 4
Table 5 – Assessment results by product type
Product type Number of samples tested (%) Satisfactory Investigative
Basil 282 (16.3) 281 1
Chives 74 (4.3) 74 0
Cilantro 401 (23.2) 399 2
Curly leaf parsley 140 (8.1) 140 0
Dill 160 (9.3) 160 0
Flat leaf parsley 241 (13.9) 241 0
Marjoram 9 (0.5) 9 0
Mint 191 (11.0) 190 1
Oregano 52 (3.0) 52 0
Sage 91 (5.3) 91 0
Savoury 2 (0.1) 2 0
Tarragon 26 (1.5) 26 0
Thyme 61 (3.5) 61 0
Total 1730 1726 4
Table 6 – Assessment results by season sampled
Season Number of samples tested (%) Satisfactory Investigative
Spring (March to May) 481 (27.8) 481 0
Summer (June to August) 484 (28.0) 484 0
Fall (September to November) 475 (27.5) 474 1
Winter (December to February) 290 (16.8) 287 3
Total 1730 1726 4

What do the survey results mean

Previous CanadianFootnote 10, Footnote 11 studies on the microbial safety of retail fresh leafy herbs have shown results approximating those found in this study while interim results of a U.S.Footnote 12 study on C. cayetanensis in fresh herbs show a higher prevalence rate. Differing prevalence rates between studies may be attributable to differences in product type tested, methodology, study design, etc.

Overall, our survey results indicate that imported fresh leafy herbs sold in Canada are generally safe for consumption, however they can occasionally be contaminated. Consequently, as with all foods, and especially with those that are consumed raw, good hygienic practices are recommended for producers, retailers, and consumers.

What is done with the survey results

All results are used to:

  • inform risk management decisions
  • support program design and re-design

While no illnesses were related to the investigative samples, these results triggered appropriate follow-up actions including a food safety investigation.

Can I access the survey data

Yes. The data will be accessible on the Open Government Portal.

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