In 2020, a seaside town on Minton experienced a large outbreak of aqualunosis following a community festival. Epidemiological investigation revealed that locally caught fish served raw in a traditional dish was the likely source of infection. While some festival attendees began to experience diarrhoea and abdominal pain shortly after the event, other attendees became ill several days later.

Q25. What is the most likely reason for the variation in incubation periods among affected individuals?