After more than four years from the beginning of the study 26 patients from the originally decided goal number of 30 patients had completed at least two years of follow-up. At this time (January 2005) it was decided to open the code and proceed with the analysis of those patients, which turned out to be 13 chloroquine-treated and 13 placebo-treated patients. The last 4 patients (who were not included in the analysis) are currently under treatment but their follow-up will end next year (2 patients are received chloroquine and the other 2 placebo).