Smart Animals: Sick Mouse Shy Away From Their Group to Prevent Transmission
It is widely accepted that animals tends to have changes in their behavior when they are sick. They become less active and less likely to socialize with their peers. Now, a new study from the University of Zurich reveals that such changes in the behavior of sick animals might potentially prevent transmission of the disease among their group.
The study, published in the journal Scientific Reports, shows that sick mice shy away and isolate themselves from others. By avoiding social contacts, sick mice are able to greatly reduce the extent of disease spread.
For the study, the researchers conducted an experiment on 257 free-living adult mice inhabiting a barn with 40 artificial nest boxes. Each mouse was implanted with transponder tags read by antennas in the nest boxes. The mice formed about 11 to 12 unconnected social groups. To simulate an infection, the researcher injected one mouse per group with either lipopolysaccharides (LPS) or saline, as control. In total, about 37 mice were injected with LPS, while the control group comprises of 35 mice.
Despite the ability of mice to detect other sick mice, the researchers were surprised when healthy mice in the same social group did not avoid of shun the sick mice. As a matter of fact, the healthy mice interacted with the sick mice and other mice more or less in the same way as before the experiment started.
However, the sick mice shy away from their group. "Such a change in the behavior of the sick mouse may protect relatives in the same group from catching the disease, which could be beneficial from an evolutionary perspective," explained lead author Patricia Lopes from the Department of Evolutionary Biology and Environmental Studies at the University of Zurich, in a statement.
Using mathematical models to predict how the changes in behavior of sick mice affect the spread of disease, the researchers discovered that the behavioral changes in sick mice leading to reduced social contact greatly reduced the speed and extent of the disease, preventing potential outbreak.