Vicente Maco1, Leny Bravo2, Luis A Marcos3. 1. Institute of Tropical Medicine Alexander von Humboldt, Universidad Peruana Cayetano, Heredia, Lima, Peru. vicente_maco@hotmail.com. 2. Private University San Juan Bautista, School of Medicine, Chorrillos, Lima, Peru. 3. Institute of Tropical Medicine Alexander von Humboldt, Universidad Peruana Cayetano, Heredia, Lima, Peru.