How do animal lice transmit diseases?

Animal lice transmit diseases primarily through the act of sucking blood from their hosts. When lice feed, they can introduce pathogens into the bloodstream. This is because lice are more than just nuisances; they can carry and spread diseases such as typhus fever and relapsing fever through their bites. As they breach the skin to draw blood, they may also release saliva that can contain infectious agents, creating a route for disease transmission.

In contrast, other mechanisms such as chewing on skin, serving as true parasites, or laying eggs in nests do not effectively convey how lice specifically transmit diseases through their feeding habits. While being true parasites means they rely on their hosts for survival and can cause harm, it does not directly relate to the transmission of disease. Therefore, the primary means of disease spread by lice is through their bloodsucking behavior.