1. Postgraduate Program in Animal Science, State University of Maranhão, Sao Luis 65055-310, Brazil
2. Veterinary Medicine Graduation School, State University of Maranhão, Sao Luis 65055-310, Brazil
3. Postgraduate Programs in Chemistry, Federal University of Maranhão, São Luís 65080-805, Brazil
4. Laboratory of Immunomodulation and Protozoology, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, Rio de Janeiro 21041-250, Brazil