We present a set of data on human and chicken Toxoplasma gondii
seroprevalence that was investigated and analysed in light of groundwater
vulnerability information in an area endemic for waterborne toxoplasmosis in Brazil.
Hydrogeological assessment was undertaken to select sites for water collection from
wells for T. gondii oocyst testing and for collecting blood from
free-range chickens and humans for anti-T. gondii serologic testing.
Serologic testing of human specimens was done using conventional commercial tests and
a sporozoite-specific embryogenesis-related protein (TgERP), which is able to
differentiate whether infection resulted from tissue cysts or oocysts. Water
specimens were negative for the presence of viable T. gondii
oocysts. However, seroprevalence in free-range chickens was significantly associated
with vulnerability of groundwater to surface contamination (p < 0.0001; odds
ratio: 4.73, 95% confidence interval: 2.18-10.2). Surprisingly, a high prevalence of
antibodies against TgERP was detected in human specimens, suggesting the possibility
of a continuous contamination of drinking water with T. gondii
oocysts in this endemic setting. These findings and the new proposed approach to
investigate and analyse endemic toxoplasmosis in light of groundwater vulnerability
information associated with prevalence in humans estimated by oocyst antigens
recognition have implications for the potential role of hydrogeological assessment in
researching waterborne toxoplasmosis at a global scale.
The association of single nucleotide polymorphisms (SNPs) in the interferon (IFN)-γ
gene ( IFNG ) with different types of retinal scar lesions
presumably caused by toxoplasmosis were investigated in a cross-sectional
population-based genetic study. Ten SNPs were investigated and after Bonferroni
correction, only the associations between SNPs rs2069718 and
rs3181035 with retinal/retinochoroidal scar lesions type A (most
severe scar lesions) and C (least severe scar lesions), respectively, remained
significant. The associations of two different IFNG SNPs with two
different types of retinal lesions attributable to toxoplasmosis support the
hypothesis that different inflammatory mechanisms underlie the development of these
lesions. The in vitro analysis of IFN-γ secretion by peripheral blood mononuclear
cells stimulated with Toxoplasma gondii antigens was also
investigated. The association between SNP rs2069718 and type A scar
lesions revealed that differential IFN-γ levels are correlated with distinct
genotypes. However, no correlation was observed with IFN-γ secretion levels and the
SNP rs3181035 , which was significantly associated with type C scar
lesions. Our findings strongly suggest that immunogenetic studies of individuals with
congenital or postnatally acquired infection are needed to better understand the role
of IFN-γ and its polymorphisms in the pathogenesis of ocular toxoplasmosis.
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