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Viruses in Fresh Leafy Herbs and Fresh Leafy Vegetables – April 1, 2017 to March 31, 2018 and April 1, 2020 to March 31, 2021

Food microbiology – Targeted surveys – Final report

Summary

A targeted surveyFootnote 1 analysed 829 samples of whole or trimmed fresh leafy herbs and 230 whole or trimmed fresh leafy vegetables over a 2-year period from April 1, 2017 to March 31, 2018 and April 1, 2020 to March 31, 2021. All samples were tested for the presence of Hepatitis A Virus (HAV) and Norovirus (NoV) Genotypes I and II (GI, GII).

99.9% of the fresh leafy herb and 100% of the fresh leafy vegetable samples tested were found to be satisfactory. HAV and NoV GI were not found in any of the samples while NoV GII was found in 1 of the 829 (0.1%) fresh leafy herb 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 fresh leafy herbs and fresh leafy vegetables 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 fresh leafy herbs and fresh leafy vegetables sold at retail in Canada. Fresh produce including fresh leafy herbs and fresh leafy vegetables are popular among CanadiansFootnote 2, as they provide a healthy and convenient way to meet Canada's food guideFootnote 3 recommendation to eat plenty of fruits and vegetables. Unfortunately, a wide variety of produce have been associated with recallsFootnote 4 and foodborne illness outbreaksFootnote 5. In Canada, among all of the known food-borne pathogens (bacteria, viruses, parasites), NoV is the leading cause of food-borne illnesses and hospitalizations and the second leading cause of deathFootnote 6.

Fresh produce, including leafy herbs and leafy vegetables can be contaminated with viruses through contact with human 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, viruses 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 viruses on produce are of concern as they are a commonly consumed by Canadians and are generally consumed raw.

When was the survey conducted

The survey was conducted over a 2-year period from April 1, 2017 to March 31, 2018 and April 1, 2020 to March 31, 2021.

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 829 whole or trimmed fresh leafy herb and 230 whole or trimmed fresh leafy vegetable samples were collected. Imported fresh leafy herb samples were collected from April 1, 2017 to March 31, 2018. Imported and domestic fresh leafy vegetable and imported and domestic fresh leafy herb samples were collected from April 1, 2020 to March 31, 2021. Imported samples were collected evenly throughout the year while domestic samples were collected during the summer months to reflect the domestic production season. A sample consisted of a single or multiple consumer sized packages of the same lot weighing at least 100g for fresh leafy herbs or 150g for fresh leafy vegetables.

What were the samples tested for

All samples were tested for the presence of HAV and NoV GI, GII.

What methods were used to test the samples

Samples were analyzed using methods that detect the presence of ribonucleic acid (RNA) of HAV and NoV GI, GII.

How were the samples assessed

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

Table 1 – Assessment criteria
Virus Satisfactory Investigative
HAV Not detected Detected
NoV GI, GII Not detected Detected

What were the survey results

HAV and NoV GI RNA were not found in any of the fresh leafy herb (n=829) or fresh leafy vegetable (n=230) samples. NoV GII RNA was not found in any of the fresh leafy vegetable samples (n=230), but was found in 1 of the fresh leafy herb (n=829) samples.

Table 2 – Assessment results
Virus Number of samples tested Satisfactory (%) Investigative (%)
HAV 1059 1058 0
NoV GI 0
NoV GII 1Table note a
Total 1059 1058 (0.09) 1 (0.09)

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

Table 3a – Product type and origin of fresh leafy herb samples
Product type Number of domestic samples tested Number of imported samples tested
Basil N/A 89
Chives N/A 33
Cilantro 1 98Table note b
Curly leaf parsley 2 74
Dill 1 63
Flat leaf parsley 8 85
Marjoram N/A 12
Mint 3 81
Oregano N/A 60
Rosemary N/A 64
Sage 1 66
Savoury N/A 15
Tarragon N/A 32
Thyme N/A 41
Total (%) 16 (1.9) 813 (98.1)
Table 3b – Product type and origin of fresh leafy vegetable samples
Product type Number of domestic samples tested Number of imported samples tested
Arugula 6 6
Boston lettuce 4 1
Collards 3 1
Endive 1 3
Escarole N/A 1
Green leaf lettuce 16 11
Iceberg lettuce 11 18
Kale 16 9
Radicchio 1 5
Red leaf lettuce 4 9
Romaine lettuce 13 9
Spinach 20 42
Swiss chard 4 2
Mixed leafy vegetables 7 7
Total (%) 106 (46.1) 124 (53.9)
Table 4 – Production practice and origin of fresh leafy herb and vegetable samples
Production practice Number of domestic fresh leafy herbs tested Number of imported fresh leafy herbs tested Number of domestic fresh leafy vegetables tested Number of imported fresh leafy vegetables tested
Conventional 15 694 94 86
Organic 1 119Table note c 12 38
Total 16 813 106 124
Table 5 – Country of origin of fresh leafy herb and vegetable samples
Country of origin Number of fresh leafy herbs tested (%) Number of fresh leafy vegetables tested (%)
Canada 16 (1.9) 106 (46.1)
China 1 (0.1) N/A
Colombia 87 (10.5) N/A
Dominican Republic 104 (12.5) N/A
Ecuador 1 (0.1) N/A
Guatemala Not Applicable (N/A) 1 (0.4)
Israel 77 (9.3) N/A
Jamaica 7 (0.8) N/A
Mexico 148 (17.9) 3 (1.3)
Morocco 3 (0.4) N/A
Peru 42 (5.1) N/A
United States 311Table note d (37.5) 120 (52.2)
United States and Mexico 1 (0.1) N/A
Vietnam 30 (3.6) N/A
UnknownTable note e 1 (0.1) N/A
Total 829 230
Table 6 – Seasonal collection and origin of fresh leafy herb and vegetable samples
Season sampled Number of domestic fresh leafy herbs tested Number of imported fresh leafy herbs tested Number of domestic fresh leafy vegetables tested Number of imported fresh leafy vegetables tested
Spring (March to May) N/A 187Table note f N/A 13
Summer (June to August) 11 205 54 14
Fall (September to November) 5 235 52 64
Winter (December to February) N/A 186 N/A 33
Total 16 813 106 124

What do the survey results mean

Previous CanadianFootnote 7Footnote 8Footnote 9 studies on the microbial safety of retail fresh leafy herbs and vegetables have shown results approximating those found in this study.

Overall, our survey results indicate that fresh leafy herbs and vegetables 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

No illnesses were associated with the investigative sample. The investigative sample triggered appropriate follow-up activities which may have included:

  • follow-up with the importer
  • review of manufacturer production, sanitation, and distribution practices

Can I access the survey data

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

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