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A quiet invader is lurking within about half of the global population. This invader is a parasite called Toxoplasma gondii, generally acquired through consuming undercooked contaminated meat or coming into contact with cat feces. Beyond initial flu-like symptoms, healthy adult humans often have no apparent symptoms but carry this microscopic stowaway for life. Toxoplasmosis has drawn interest from scientists, mainly because of the strange behavioral changes it induces in rodents. Infected rats show diminished fear responses, particularly to cat urine—a scent they usually avoid. Research indicates that this may be due to T. gondii infection causing inflammatory changes in the brain regions associated with anxiety and fear. But why would a rodent-parasitizing pathogen care about felines? For T. gondii, it's an essential part of its lifecycle. The parasite can only reproduce sexually in cats; infected rodents becoming fearless increases their chance of being eaten by cats, enabling T. gondii to complete its reproductive cycle. Notably, toxoplasmosis has also been linked in humans to various psychological effects, such as an increased likelihood of risk-taking behaviors or certain mental disorders like schizophrenia. Nonetheless, these correlations should be interpreted with caution as more researches are needed.
Intriguing Insights Into the Parasite Toxoplasma Gondii
Toxoplasma gondii is a parasite that alters the behavior of rats in order to increase its own chance of survival.
A quiet invader is lurking within about half of the global population. This invader is a parasite called Toxoplasma gondii, generally acquired through consuming undercooked contaminated meat or coming into contact with cat feces. Beyond initial flu-like symptoms, healthy adult humans often have no apparent symptoms but carry this microscopic stowaway for life. Toxoplasmosis has drawn interest from scientists, mainly because of the strange behavioral changes it induces in rodents. Infected rats show diminished fear responses, particularly to cat urine—a scent they usually avoid. Research indicates that this may be due to T. gondii infection causing inflammatory changes in the brain regions associated with anxiety and fear. But why would a rodent-parasitizing pathogen care about felines? For T. gondii, it's an essential part of its lifecycle. The parasite can only reproduce sexually in cats; infected rodents becoming fearless increases their chance of being eaten by cats, enabling T. gondii to complete its reproductive cycle. Notably, toxoplasmosis has also been linked in humans to various psychological effects, such as an increased likelihood of risk-taking behaviors or certain mental disorders like schizophrenia. Nonetheless, these correlations should be interpreted with caution as more researches are needed.
Sources:
Webster JP et al (2013) 'The Influence of Toxoplasma Gondii on Host Behaviour: An Update on Mechanisms and Pathology'. In: Weiss L., Kim K. (eds) Toxoplasma Gondii: The Model Apicomplexan - Perspectives and Methods (2nd ed). Academic Press; Vyas A et al (2007) 'Behavioral changes induced by Toxoplasma infection of rodents are highly specific to aversion of cat odors'. PNAS.
Webster JP et al (2013) 'The Influence of Toxoplasma Gondii on Host Behaviour: An Update on Mechanisms and Pathology'. In: Weiss L., Kim K. (eds) Toxoplasma Gondii: The Model Apicomplexan - Perspectives and Methods (2nd ed). Academic Press; Vyas A et al (2007) 'Behavioral changes induced by Toxoplasma infection of rodents are highly specific to aversion of cat odors'. PNAS.