Food poisoning in the UK tends to start increasing as the summer weather draws on, peaking in July-August and then falling slowly back to baseline levels in December.30

Norovirus is considered a predominantly winter virus, although infections can occur in the summer. The trend for infections is to increase from late September and return to baseline levels by late June. However, the timing and extent of peak infection levels varies from year, ranging from mid-December to late March-April, with as much as a three-fold difference in laboratory results from year to year.14

Rotovirus laboratory reports since 2009 indicate that infection levels start to increase from the last week of December, peaking at some point between February and April and returning to baseline by July. However, the impact of introducing the rotavirus vaccine has seen peak infection levels reduce significantly since 2013.

Health burden varies according to pathogen. Data from 2009 suggests that Campylobacter may have caused potentially up to 436,000 food-related cases which resulted in 55,600 GP consultations. However, it was responsible for possibly fewer than 1,400 food-related hospital admissions, compared to around 2,500 admissions due to Salmonella and 2,200 admissions for E. coli O157.

The same data indicates that while there may have been around 75,000 cases of foodborne norovirus, they resulted in 3,240 GP consultations and under 500 hospital admissions.12

When looking at outbreaks, around 23 per cent of people with E coli infection might be admitted to hospital. This compares to less than 2 per cent of people in outbreaks of C. perfringens, Campylobacter, Giardia, norovirus and rotavirus.