Sick mice isolate themselves to reduce the chances of spreading the disease

We know that when we are sick, we should stay at home in order not to spread the disease. But how do animals approach this problem without our extensive knowledge about infections? A new research from the University of Zurich and the ETH Zurich revealed that sick animals also isolate themselves from their peers.

Mice have ability to sense if one of them is sick, but isolation is usually done by the sick individual itself. Image credit:

Mice have ability to sense if one of them is sick, but isolation is usually done by the sick individual itself. Image credit:

Scientists conducted experiments with wild house mice. They showed that sick mouse tends to stay away from its social group in order not to spread the disease. It has been noticed before, but usually scientists would only consider it a reduced activity because of the illness. This new information will help improving models predicting the spread of infectious diseases like influenza or Ebola in humans.

A first impression of the readers may be that the methods of the research had to be rather simple. However, in reality they included experimental manipulations of free-living mice, radio frequency tracking of animals, social network analysis and disease modelling. Injection of lipopolysaccharides helped simulating an infectious disease. Surprisingly, other mice did not avoid a sick one – they interacted with it as usual. However, the mouse that felt sick isolated itself from its social environment. Scientists say that the purpose of such behaviour must be protection of the relatives in the same group, which has an evolutionary function.

After this experiment scientists used a model to see how a disease would spread taking into account protective behaviour of the sick animal. Patricia Lopes, lead author of the study, said: “When we account for the behavioural changes and how they affect social contacts, we find that the speed and the extent of disease spread are greatly reduced”. It means that self-isolation does help fighting the spread of the disease.

Scientists say that with such factors as climate change, habitat disturbance and human connectivity will contribute to more outbreaks of infectious diseases in the future. Feeling sick is an indication for the person – there is no reason to have an extensive amount of social interaction if one feels sick. This research shows that for wild mice isolation helps stopping infections, which means that it could be beneficial for us too.