Introduction

Toxoplasma gondii is a protozoan parasite that infects a large spectrum of warm-blooded animals, including humans (^{DUBEY, 2010}). Rodents play an important role in the life cycle of T. gondii because they are one of the important sources of infection for domestic and feral cats. Studies of cat predation on wildlife suggest that rodents comprise about two-thirds of the prey consumed, although this may vary according to the season, rodent abundance, and the availability of other prey (^{MARSHALL et al., 2004}). Antibodies to T. gondii in small wild rodents from Brazil were reported in Proechimys sp., Rattus rattus, Nectomys rattus, Akodon cursor, and Thrichomys laurentius (^{COSTA et al., 2012}; ^{SIQUEIRA et al., 2013}). In urban area R. rattus presented antibodies to T. gondii (^{FERRARONI & MARZOCHI, 1980}; ^{COLA et al., 2010}), and viable parasites were isolated by bioassay and detected by PCR in Rattus norvegicus and Mus musculus (^{MURADIAN et al., 2012}).

Marsupials in Americas are considered resistant to clinical toxoplasmosis (^{CANFIELD et al., 1990}). The occurrence of T. gondii antibodies in marsupials in Brazil were reported in different species of Didelphis and Monodelphis(^{FERRARONI & MARZOCHI, 1980}; ^{YAI et al., 2003}; ^{SIQUEIRA et al., 2013}).

The Atlantic Forest is known of its biodiversity. Originally occupied 1,300,000 km², however, nowadays, only 7% of this area remained. Despite its devastation, the Atlantic Forest is a rich biome with about 850 species of birds and 270 species of mammals (^{Brasil, 2014}). This study aims to investigate the occurrence of anti-T. gondiiantibodies in wild rodents and marsupials captured in the Atlantic Forest, in the state of São Paulo, southeastern region of Brazil.

Material and Methods

The use of the wild animals was approved by the Brazilian Institute of Natural Resources (IBAMA No.22212-1) and the project was in accordance with the Ethical Principles in Animal Research by Brazilian College of Animal Experimentation.

Results and Discussion

Samples were obtained from 151 rodents and 48 marsupials, from eight rodent and four marsupial species. The occurrence of T. gondii antibodies was 8.6% (13/151) for rodents and 10.4% (5/48) for marsupials. From the rodents, three different species were positive: Akodon spp. (10.5%, 11/105), Oligoryzomys nigripes (5.5%, 1/18), Rattus norvegicus (100%, 1/1), and from the marsupials only the species Didelphis aurita had T. gondii antibodies (12.5%, 5/40). Rodents were captured in all investigated areas, however, the positive animals were only found in the Municipality of Arujá (5.5%), Santo André (21.7%) and São Bernardo do Campo (17.5%). Marsupials were captured in six investigated areas and positive animals were observed in Municipality of Diadema (25%), São Bernardo do Campo (16.6%) and São Paulo (60%). Table 1 presents the occurrence of antibodies to T. gondii per rodent and marsupial species per municipality.

Antibody titers ranged from 25 to 6400 for the rodents and from 25 to 3200 for the marsupials (Table 2).

The occurrence of T. gondii antibodies in marsupials in Brazil were also previously reported in Didelphis marsupialis and Didelphis albiventris, captured in the Brazilian Savanna (^{YAI et al., 2003}), and in Didelphis aurita, Monodelphis domestica, Metachirus nudicaudatus, Marmosa murina, Marmosa demerarae and Marmosa sp. collected in northeastern region of the Atlantic Forest, in the state of Pernambuco (^{FERRARONI & MARZOCHI, 1980}; ^{SIQUEIRA et al., 2013}).

Toxoplasma gondii antibodies are reported here for the first time in the rodent Oligoryzomys nigripes. This species is abundant in the Atlantic Forest and Araucaria forest areas throughout Southern Brazil and the Southern part of the gallery forests of the Cerrado, extending to the Pampas on the southern edge of Brazil. This species has a generalist habit being found within forests and open vegetation formations and has a great capacity for adaptation to anthropic environments, including agricultural areas dwellings and barns entering in contact with domestic animals (^{PÜTTKER et al., 2008}; ^{DALMAGRO & VIEIRA, 2005}) which make this specie important in the epidemiology of T. gondii.

Although 52% of all marsupials represented by all four species were captured in the Ecological Reserve, at Peruíbe, none had antibodies to T. gondii. Similar results were observed for the rodents, with all the 25 rodents from the Reserve been seronegative to T. gondii. In the Reserve exist various species of wild cats, Leopardus pardalis, Puma concolor, Panthera onca, Felis pardalis, Puma yagouaroundi (^{PARDINI & DEVELEY, 2004}; ^{MARTINS et al., 2008}), that might play role in the zoonotic cycle of T. gondii being the define host, as suggested by ^{Cañón-Franco et al. (2013)}. However the absence of positive animals indicate that this environment is on equilibrium and emphasizes the importance of the anthropogenic pressure on the Atlantic rainforest, since all positive animals were captured on areas under high anthropogenic effect, where interactions between small mammals and domestic cats are easily observed. Such impact should be further investigated.

References