Introduction In Brazil, has been mandatory to report congenital syphilis (1986), syphilis in pregnancy (2005) and acquired syphilis (adults) (2010) to the national surveillance system. Until June 2016, 2 27 663 cases of acquired syphilis were reported in Brazil, the state of São Paulo accounted for 44%. The aim of this study was to describe the trends observed from 2011 to 2015 of reported cases of acquired syphilis, syphilis in pregnancy and congenital syphilis in the state of São Paulo.

Methods An ecological study of historical series was conducted, assessing data of reported cases from 2011 to 2015 in the State of São Paulo, Brazil. The goodness of fit via r² and p<0.05 were used to determine which models were most appropriate.

Results In the period 12 312 cases of congenital syphilis (CS), 25 399 cases of syphilis in pregnancy and 93 937 cases of acquired syphilis were notified. There was an increase number of cases (2011 and 2015): CS (1,517 to 3,437 - increased 2.3 times); syphilis in pregnancy (3,205 to 6,956- increased 2.2 times); acquired syphilis (10,841 to 25,987- increased 2.4 times). There was a trend of increase for the three reported diseases with an annual mean increase of 3894 cases/year (r²=0.9938) for acquired syphilis, 998 cases/year (r²=0.9849) for syphilis in pregnancy and 490 cases/years (r²=0.9969) for CS. Analysing acquired syphilis by gender, there was a trend of 2528 cases/year increase in men (higher in the age from 20 to 24 years - 488 cases/year) and 1366 cases/ear increase in women (higher in the age from 20 to 24 years - 264 cases/year). Among reported cases of syphilis in pregnancy, the highest increase was in the age of 20 to 24 years with 350 cases/year.

Conclusion The increase in reported syphilis cases could be explained by the reduction of underreporting; increase in early diagnosis of pregnant women; increase in cases of specific populations with higher frequency of young men. It is urgent to implement preventive and control actions towards young population, which seems to be disproportionally affected.