Scientists have discovered that pathogens have the ability to change the behavior of the hosts through various mechanisms. Behavior changes by host-pathogen interactions can help the pathogen spread and reproduce more effectively. Pathogens can affect their host's behavior, physiology, and gene expression, leading to increased aggression, suicidal tendencies, or deformities. Toxoplasma gondii can make infected hosts more prone to risk-taking behavior and aggression, leading to a lack of aversion to cat odor and an increased risk of car accidents. Rabies can also influence the biting habits of infected animals, making it more likely that the virus will be transmitted through saliva. Some parasites, such as the Gordian worm, Cordyceps fungi, Mermis nematode, and Dicrocoeliumdendriticum, can even manipulate their hosts into committing suicide. Other parasites, such as Riveiroia spp. and Leucochloridium spp., can cause physical deformities in their hosts, making them more vulnerable to predators. Despite the previous research, there remains significant uncertainty surrounding host-pathogen interactions. Reviewing host behavior manipulationsby pathogens is a critical and fascinating medical and psychological science area.