Table 2 Characteristics of included studies
| Â | N | % |
|---|---|---|
Total number of studies | 13 | Â |
Year of study | ||
 Before year 2000 | 8 | 61.5 |
 2000 and later | 4 | 30.8 |
 unknown | 1 | 7.7 |
Region of study | ||
 Europe | 3 | 23.1 |
 North America | 5 | 38.5 |
 Africa | 2 | 15.4 |
 Asia | 2 | 15.4 |
 Unknown | 1 | 7.7 |
Study design | ||
 Descriptive | 4 | 30.8 |
 Case control | 4 | 30.8 |
 Retrospective cohort | 3 | 23.1 |
 Experimental study | 2 | 15.4 |
Setting of exposure | ||
 Catered meal | 5 | 38.5 |
 Outdoor activity | 2 | 15.4 |
 Picnic | 2 | 15.4 |
 Experimental study | 2 | 15.4 |
 Community | 1 | 7.7 |
 Restaurants | 1 | 7.7 |
Food vehicle category | ||
 Red meat | 2 | 15.4 |
 Dairy and dairy products | 2 | 15.4 |
 Salad | 3 | 23.1 |
 Non-foodborne | 1 | 7.7 |
 Other | 3 | 23.1 |
 Unknown | 2 | 15.4 |