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Received Oct 15, 2011; Accepted Nov 28, 2011
1. Introduction
Chagas disease is a major public health threat in Latin America, and dogs are an important domestic reservoir for infection in humans [1]. In Argentina, the presence of dogs in dwellings increases the risk for human infection about 3–5 times [2].
Dogs have also been used as a model for evaluating the process of disease development following Trypanosoma cruzi infection [1, 3, 4]. Several studies have reported the use of different strains and doses to evaluate the infection, which makes difficult to correlate and compare the results between them. Strains such as Berenice 78 [5, 6], SC-1 [7] or Tc-O [8] have been used, with doses ranging from one thousand up to 5 million trypomastigotes per kilogram of body weight. It has been demonstrated that different strains, routes of inoculation and animal species developed different degrees of lesion and immunological response and infection affected a variety of organs [9].
Indeed, T. cruzi parasites have variable tropisms to different organs, which has been attributed to the strain, number of parasites, the origin of trypomastigotes, the route of infection, among others [10, 11]. Other studies have compared blood and metacyclic trypomastigotes, and the latter were found to be more pathogenic since they produced a more severe form of disease [6].
In order to evaluate the effect of infection by different parasite doses on the immunopathology of T. cruzi infection in dogs, we evaluated here three different doses of metacyclic trypomastigotes of the Sylvio X10/4 strain, considered a pathogenic strain [9], administered via intraperitoneal, to determine the best challenge model to further study the immunopathology of T. cruzi in this species.
2. Materials and Methods
2.1. Dogs
Eleven clinically healthy mongrel dogs ranging from 4 to 6 months of age, without clinical and electrocardiographic (ECG) alterations seronegative for T. cruzi IgG by ELISA, were used. They were dewormed, and vaccinated twice against canine distemper virus, canine parvovirus, parainfluenza, leptospira, and adenovirus type 2, and fed with a balanced commercial food. The dogs were numbered and handled as described by the official protocols of NOM-062-ZOO-1999. All procedures were carried out in compliance with the Ethical committee for animal welfare of the Center of Advanced Studies on Animal...