Results
T. gondii -specific IgG antibodies were found in 59.6% (28/47) of
captive NPs and 11.6% (23/198) of wild NPs. In captive NPs,
seroprevalence was high for both species: 59.1% (26/44) of A.
geoffroyi and 66.7% (2/3) of C. imitator . There were no
significant differences in species or sex with 58.6% (17/29) ofA. geoffroyi females and 60.0% (9/15) males being positive,
while for C. imitator , 50.0% (1/2) females and 100% (1/1) male
had antibodies (Table 3, Table 4).
In contrast, there was a significant difference in seroprevalence among
wild NP species (X2 = 20,072; df = 3;P = 0.0002): A. geoffroyi had the highest seroprevalence
with 40% (2/5), followed by C. imitator with 30% (11/37) andA. palliata with 6.6% (10/151), while no S. oerstediiwere positive. No significant differences were found regarding sex for
any of the species, however, greater seroprevalence was observed for
females in the three positive species (Table 3, Table 5).
Antibody titers tended to be relatively low (Median = 8) in wild NP
(<128), with the exception of four individuals: one A.
geoffroyi and two C. imitator with antibody titers of 262,144
and one A. geoffroyi with a titer of 1,048,576). In contrast,
antibody titers were considerably higher (Median = 262144) in captive
NP, from 8,192 to 33,554,000 (Table 6). These two groups of NP were
statistically different in their titer values (Mann-Whitney U= 303, n1=
52, n2=34, p<0.00001 two tailed).
The model that best accounted for seropositivity among A.
palliata (minimizing AIC) was forest cover and annual precipitation
(Figure 1.B., Table 2), with a positive relationship between forest
cover and seropositivity and inverse relationship with annual
precipitation. However, evidence weights (wi) for the second and third
best-supported models were 1.02 and 1.94 times lower than model 1
respectively, which suggests that no one model is strongly supported as
the best candidate. The second best model was annual precipitation (ΔAIC
= 0.04) and the third was for human population density and annual
precipitation (ΔAIC = 1.32). Notably, the precipitation parameter
appeared among the top eight models.
For C. imitator, annual precipitation alone best accounted for
seropositivity with a significant inverse relationship (Figure 1.C.,
Table 2). The next best models were forest cover and annual
precipitation (ΔAIC = 1.09) and human population density and
precipitation (ΔAIC = 1.5), with evidence weights 1.73 and 2.12 times
lower than model 1, respectively. Again, the effect of precipitation on
seropositivity was important for C. imitator when comparing the
sum of the weights of Akaike (wi) in the models that contained this
variable (0.98) with respect to the others, such as forest cover (0.35),
population density (0.3) and sex (0.29).