Influenza in seals

There are four types of influenza in total. Types A, B and C cause flu in humans. Influenza types A and B can occur in marine mammals, such as in seals. Influenza can cause a huge wave of disease in wild seals.

Influenza is not clearly visible by one specific complaint or change in appearance. Seals can have several complaints at the same time. The characteristics of influenza B are unknown. Possible features of influenza A are:

• Weakness
• Bad coordination
• Short of breath
• Swollen neck
• White or bloody runny nose
• Pneumonia

The virus droplets are spread by, among other things, coughing and sneezing, and are then inhaled again. Influenza is extremely contagious. Not only for seals, but also for humans. That is why it is very important to protect both the seals and ourselves if someone is carrying the virus.

Common and grey seals can be sick with influenza. It is shown that mainly common seals suffer from the influenza virus. In several major outbreaks of the virus, mainly common seals died. The last outbreak of influenza was in 2014, when thousands of common seals washed up dead on the coasts of the Netherlands, Germany, Denmark and Sweden (1).

Seals can also get influenza from birds. In October 2015, the avian flu virus (H10N7) was the cause of major deaths among harbor seals (2). Seals probably contracted the virus through direct or indirect contact with wild birds or their faeces.

In June 2022, researchers found the avian flu virus in three seals in Germany, but it hasn't sparked a massive outbreak. The fact that the virus is transferred from a bird to a marine mammal means that there is a chance that humans can also be infected.

It is not possible to cure influenza. There is no medicine for this virus. We can only try to reduce the symptoms and wait until the seal gets better.