Infectious diseases: Outbreaks, Epidemics, Pandemics

Viruses and bacteria are everywhere. Infectious diseases spread even in our age of modern medicine. What constitutes an outbreak? An epidemic or pandemic? Are there epidemics currently happening? What should I do in the event of a pandemic? In this section you’ll find definitions, the latest figures (for example on flu) and our recommendations.


In terms of infectious diseases an outbreak means a sudden increase in the incidence of a specific disease within a delimited community, region or season. A single case can also constitute an outbreak if the disease has never occurred before or not for a long time.

Outbreaks usually involve diseases that spread via contaminated water or food. In Switzerland, for example, various strains of salmonella and noroviruses repeatedly lead to outbreaks.

The origin of the outbreak (technical term: source) can be worked out by means of an outbreak investigation. This involves interviewing the people affected or doing molecular biological typing on the pathogens. Once found, the source should be remediated or eradicated. As a rule this puts a stop to the outbreak.


An epidemic is when an infectious disease occurs very frequently within a delimited area and for a limited time. In Switzerland this happens on a seasonal basis with diseases such as the flu, Lyme borreliosis and tick-borne meningitis (TBE or early summer meningoencephalitis), and in predominantly urban regions, for example with sexually transmitted diseases.

Our role at the FOPH is to analyse cases of this sort, assess the risks and draw up epidemiological reports as the basis for vaccination recommendations, control strategies and prevention programmes.


A pandemic is when a specific infectious disease spreads in many countries or continents. It can put a large portion of the world’s population at risk. The most significant are flu pandemics, which are caused by influenza viruses and can occur at any time. AIDS is often also described as a pandemic.

In Switzerland we’re prepared for a flu pandemic with a pandemic plan. We provide businesses with a handbook and the general public with recommendations for hygiene.

Whether it’s an outbreak, epidemic or pandemic, when it comes to internationally relevant events Switzerland works closely with other countries and international organisations.

Current outbreaks and epidemics

What epidemics are spreading worldwide? What outbreaks are currently occurring in Switzerland? The FOPH publishes current status reports, FAQs and recommendations for the public on selected infectious diseases in Switzerland and abroad.

Past outbreaks and epidemics

Blick in die Vergangenheit: Welche länderübergreifenden Epidemien haben die Schweiz bedroht? Welche relevanten Ausbrüche waren in der Schweiz zu verzeichnen? Hier sind historische Dokumente zu ausgewählten Krankheiten zu finden.

Pandemic preparedness

Here you’ll find an overview of pandemic preparedness measures in Switzerland and their significance.

Flu pandemic: Hygiene in the event of a flu pandemic

The spread of viruses and respiratory infections is facilitated by large gatherings of people, stale air, travelling and commerce. Hygienic measures help reduce the risk.

Flu pandemic: Recommendations in the event of a pandemic

What to do in the event of illness? Here you’ll find information and recommendations on how to prevent and treat flu during a flu pandemic.

Last modification 11.01.2019

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