The outbreak of the H5N1 variant of avian flu was the most remarkable outbreak in 2021. In October of that year, the Netherlands experienced the start of the biggest outbreak of avian flu since 2003. This is one of the observations in the 2021 Zoonoses Report, an annually published report of the National Institute for Public Health and the Environment (RIVM) and the Netherlands Food and Consumer Product Safety Authority (NVWA). Zoonoses are infectious diseases that can be transmitted from animals to humans and vice versa.

Before 2021, outbreaks of avian flu in the Netherlands mainly occurred in winter with the arrival of migratory birds. Starting from October 2021, the virus continued to circulate among wild birds and poultry in the Netherlands, and since then, avian flu infections have occurred year-round. 

In 2021, avian flu was found in 263 dead wild birds. The highest rate of infection among dead wild birds examined was observed in November (44%) and December (57%). The infected dead birds included various species of geese, as well as waterfowl and birds of prey. 

No humans were infected with avian flu in the Netherlands in 2021, but a number of wild mammals were, such as foxes. 

Fewer infections with Salmonella and Campylobacter

Some zoonoses were less prevalent in 2021 than in the years before the coronavirus pandemic. There were fewer reports of people getting infected with the Salmonella and Campylobacter bacteria, for example. Moreover, in 2021, measures were again taken to prevent the spread of the coronavirus SARS-CoV-2, such as the temporary closure of clubs, bars and restaurants, foreign travel restrictions and an increased focus on hand hygiene. These measures probably also contributed to the decrease in the number of cases of certain zoonoses.

Pandemic preparedness

Each year, the Zoonoses Report focuses on a particular theme. This year, the theme is pandemic preparedness: being prepared for outbreaks of infectious diseases. The Dutch government and scientists have started a number of initiatives to reduce the risk of the outbreak of zoonoses, which includes making improvements to outbreak contingency plans. The Zoonoses Report 2021 also describes steps that will enable earlier detection of outbreaks in the future. Some pathogens can be detected early through sewage sampling, for example.

About the Zoonoses Report

Each year, RIVM compiles the Zoonoses Report, an overview of the main zoonoses in the Netherlands. This mainly concerns cases of zoonoses that physicians and veterinarians must report (cases in humans must be reported to the Municipal Public Health Service (GGD) and those in animals to the NVWA). 

The report describes the prevalence of these zoonoses in the Netherlands. Policymakers and professionals, such as government authorities and GGDs, can use this information to take measures when necessary. 

This year, the Zoonoses Report (only in Dutch) will be published on a website for the first time and no longer as a single report.