1. INTRODUCTION
Toxoplasma gondii (T. gondii ) is a neurotropic parasite
affecting warm-blooded animals including humans1 and
is found in more or less 30% of people.2 Felines are
the final host for T. gondii , shedding in their feces up to
millions of oocyst stages daily, which become contagious in
nature.3 In people, the infection may be transmitted
by the ingestion of water or food. In this way, the majority of T.
gondii infections remain asymptomatic or maybe produce infectious
mononucleosis in people who have an intact immune system. Severe
toxoplasmosis may develop if T. gondii infects immunocompromised
patients such as acquired immunodeficiency syndrome
(AIDS).4 In parallel with the achievements after the
concept of microbiota, it is thought that microorganisms may be
associated with non-infectious pathological changes.
The pathophysiology of schizophrenia is tangled, and biological factors
are among the leading causes.5 Thus, studies focusing
to elucidate the possible agents in schizophrenia have been carried out.
In many studies conducted for this purpose, T. gondii has been
evaluated as the prominent agent in this relationship due to its tropism
and persistence in the brain.6 Several reports are
describing that T. gondii is linked to the elevated risk of mice
catching by felines,7 to modulated behavioral change
by influencing neurotransmitters in the human brain.8In humans, dysregulation of some neurotransmitters is significantly
related to schizophrenia. T. gondii can synthesize tyrosine
hydrolase and thus dopamine dysregulation may occur. Furthermore,T. gondii also modifies the level of a vast of other
neurotransmitters, including glutamate, serotonin, norepinephrine, and
γ-aminobutyric acid (GABA).9 The link between
schizophrenia and T. gondii seems to be vigorous, as evidenced by
numerous seroprevalence and neurotransmitter studies.
Worldwide, almost 800.000 people die by suicide and roughly 10 million
individuals attempt suicide annually. Suicide attempts are recognized to
be a complex mechanism, with psychological, social and biological
perspectives involved.10 In 2009, T. gondii , a
hitherto unforeseen agent, has been associated with the suicide attempt.
The possible relationship between T. gondii and suicide attempts
has also been shown in a current seroprevalence study. According to the
author, T. gondii IgG positivity was statistically highly
correlated with lower agreeableness, lower conscientiousness and higher
neuroticism personality types.11 Overall,
topic-related and current studies provide considerable evidence for the
hypothesis that T. gondii infections maybe take a key position in
the risk of the suicide attempt.12
In this case-control study, it was aimed to elucidate the relationship
between T. gondii , which was detected by serological and
molecular methods, and patients with schizophrenia, and the suicide
attempt by comparing it with the healthy individuals.