Funding for this research was provided by:
Received: 29 July 2018
Accepted: 4 December 2018
First Online: 11 December 2018
Compliance with ethical standards
: This study was funded by CNPq/DECIT (The National Research Council and the Department of Science and Technology of the Brazilian Ministry of Health), Grant number 402702/2008-5. This manuscript is solely authors’ responsibility and does not necessarily represent the official views of CNPq. CNPq did not influence on the decision to submit this manuscript or on its content. The authors declare that they have no conflict of interest.
: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and national research committee, and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. For this type of study, formal consent was waived. The research protocol was approved by the Institutional Review Board of University of Campinas on March 5th, 2009 (number 097/2009).