Seroprevalence of anti-Toxoplasma gondii antibodies in wild boars (Sus scrofa), hunting dogs, and hunters of Brazil

Abstract

Seroprevalence of Toxoplasma gondii has been extensively studied in wild boars worldwide due to the emerging risk for human infection through meat consumption. However, this is the first study that reports toxoplasmosis seroprevalence in wild boars, wild boar hunters and their hunting dogs. The aim of the present study was to evaluate the seroprevalence of anti-T. gondii antibodies in the complex wild boars, hunting dogs and hunters, and to determine the risk factors associated with seropositivity in southern and central-western Brazil. Overall, anti-T. gondii seropositivity was observed in 15/71 (21.1%) wild boars by modified agglutination test (MAT); and 49/157 (31.2%) hunting dogs and 15/49 (32.7%) hunters by indirect immunofluorescent antibody test (IFAT). Seroprevalence of toxoplasmosis in Brazilian wild boars was within the national and international range, posting wild boars as potential environmental sentinels for T. gondii presence. In addition, the findings have comparatively shown that wild boars have been less exposed to infection than hunting dogs or hunters in both Brazilian regions. Seropositivity for T. gondii was statistically higher in 12/14 (85.7%) captured wild boars when compared to 5/57 (7.0%) free-range wild boars (p = 0.000001). Similarly, captured wild boars from anthropized areas were more likely to be seropositive than of natural regions (p = 0.000255). When in multiple regression model, dogs with the habit of wild boar hunting had significant more chance to be positive (adjusted-OR 4.62 CI 95% 1.16–18.42). Despite potential as sentinels of environmental toxoplasmosis, seroprevalence in wild boars alone may provide a biased basis for public health concerns; thus, hunters and hunting dogs should be always be included in such studies. Although hunters should be aware of potential T. gondii infection, wild boars from natural and agricultural areas may present lower protozoa load when compared to wild boars from anthropized areas, likely by the higher presence of domestic cats as definitive hosts.

Seroprevalence of Toxoplasma gondii, Neospora caninum, and Leishmania spp. in hunting dogs from Mato Grosso do Sul, Brazil

“…A higher seroprevalence of T. gondii than N. caninum, as observed in this study, was also reported by AyINMODE et al (2016) andMACHACOVA et al (2016), demonstrating a greater environmental spread of these parasites in rural areas. Besides, there was no difference between T. gondii and N. caninum regarding gender, as same reported in previous studies in hunting (AyINMODE et al, 2016, CANO-TERRIZA et al, 2016, COLLANTES-FERNANDEZ et al, 2008, MACHACOVA et al, 2016, MACHADO et al, 2019 and pet dogs (CABRAL et al, 1998, DA PAZ et al, 2019, GARCIA et al, 1999 showing that there is no higher predisposition to seroconversion -------------------------------------------------------------------------Toxoplasma gondii-----------------------------------------------------------------…”

“…There also was no statistical difference in the seroprevalence of T. gondii and N. caninum between the age. Previous studies have reported a higher seroprevalence in older dogs, which is attributed to the significant cumulative exposure of dogs to this agent in the environment (CANO-TERRIZA et al, 2016, MACHACOVA et al, 2016, MACHADO et al, 2019. Only one dog had antibodies against Leishmania spp., which demonstrates the low prevalence of leishmaniasis in the rural area of Campo Grande.…”

“…The dogs were trained to practice illegal hunting of jaguars in the Cerrado and Pantanal region, which could explain this high seroprevalence of toxoplasmosis, since a previous study showed 100% of seropositivity for T. gondii in jaguars from these regions, evidencing the importance of this species in maintaining the parasite in nature (FURTADO et al, 2015). Different studies have shown a higher seroprevalence of T. gondii and N. caninum in hunting dogs than domiciliated dogs (AyINMODE et al 2016;MACHACOVA et al, 2016;MACHADO et al, 2019;ORR et al, 2019). It occurs probably because hunting dogs have free access to water and food, which could be contaminated with oocysts and tissue cysts (AyINMODE et al, 2016).…”

Seropositivity of Anti-Toxoplasma gondii Antibodies in Owners and Their Dogs Living on Island and Mainland Seashore Areas of Southern Brazil

“…Dogs have also been proposed as toxoplasmosis sentinels for human infection, mostly due to sharing inhouse spaces and related exposure to food and water sources [ 6 , 7 , 8 ]. The overall seropositivity in dogs in this study (23.3%) was lower than the 40.8% in Bahia State, northeastern Brazil [ 48 ], 40.0% [ 10 ] and the 25.4% in Sao Paulo State, southeastern Brazil [ 8 ], the 36.5% in Bahia State, northeastern Brazil [ 49 ], the 34% in Rio de Janeiro State, southeastern Brazil [ 50 ], and the 32.7% in southern and central-western Brazil [ 28 ]; only higher than the 16.3% [ 27 ] and the 7.95% in the same Parana State, southern Brazil [ 9 ]. In addition, the observed seropositivity herein was lower than the 72.7% in Cuba [ 7 ] and higher than the 18.6% [ 51 ] and the 21.6% in China [ 52 ].…”

“…To the authors’ knowledge, this was the first concomitant study on the occurrence of T. gondii antibodies in owners and their dogs living on islands and seashore mainland areas. The overall owner seropositivity in this study of the 18.0% was lower than most previous serosurveys, including the 49.8% in San Carlos Island, Venezuela [ 25 ] and all other Brazilian studies, with the 68.7% in the Pará State, northern Brazil [ 26 ], the 50.4% in the Fernando de Noronha Island, far northeastern Brazil [ 3 ], the 41.5% [ 27 ] and the 36.8% [ 9 ] in the same Parana State, southern Brazil, and average of the 32.7% in southern and central-western Brazil [ 28 ]. Seropositivity in the present study was higher than the 12.4% in Panama [ 29 ] and the 5.1% in provinces of China [ 30 ].…”