Abstract

‘Enteric infections’ is an umbrella term for a diverse group of infections in humans, primarily through the faecal-oral route. These can be caused by a diverse range of bacterial, parasitic and viral pathogens. Enteric infections usually lead to gastrointestinal symptoms such as vomiting, abdominal pain and/or diarrhoea that may or not be bloody. In some cases, these infections lead to serious symptoms such as hepatitis, blood poisoning or meningitis. Some enteric infections spread from farm animals or pets to humans. These are known as zoonoses. For other enteric infections, humans are the only host and they spread from person to person. In both cases, this often occurs through contaminated food, but also through the environment (soil/air/surface water) or direct contact with animals or faeces. In order to monitor the spread of enteric infections, RIVM charts every year how frequently such infections and their causal pathogens occur in the Netherlands.

The pathogens Salmonella, Campylobacter and norovirus, which mainly spread through food, occurred more frequently in 2021 than in 2020, but not yet as frequently as before the COVID-19 pandemic. The reduced incidence in 2020 was probably a side effect of non-pharmaceutical interventions to curb the spread of the coronavirus. In general, there were fewer measures in 2021 than in 2020. For example, there was more travel abroad in 2021. This can explain the increase compared to 2020. The number of people who became ill with the bacterium Listeria monocytogenes (listeriosis) remained the same. The Listeria bacterium can mainly be found in (smoked) fish, cheese and meat products with a longer shelf life. This also applies to leptospirosis, which is mainly contracted through contact with water and mud.

It was striking that the number of rotavirus infections, which spread from person to person, was almost back to the same level in 2021 as before the COVID-19 pandemic, especially among young children. The usual peak around February 2021 did not occur, but there was a remarkably early start to the next rotavirus season in October 2021. This was probably due to children becoming more susceptible to rotavirus infection again after a period of reduced frequency since the start of the COVID-19 pandemic.

In 2021, there were a number of noticeable food-related outbreaks caused multiple illnesses. This concerned an international Salmonella outbreak caused by eating Galia melons from Honduras, and a second Salmonella outbreak traced back to a Dutch egg-laying farm. There was also a Listeria outbreak, with the consumption of salmon as the most likely source.