RT Journal
A1 Kuehn BM
T1 SExually transmitted infections
JF JAMA
JO JAMA
YR 2009
FD February 25
VO 301
IS 8
SP 817
OP 817
DO 10.1001/jama.2009.197
UL http://dx.doi.org/10.1001/jama.2009.197
AB 
In 2007, 1.1 million diagnoses of chlamydia were reported to the CDC, a 7.5% increase since 2006, when 1.0 million cases were reported. The agency notes, however, that half of all cases go undiagnosed, and estimates that there were actually 2.8 million new cases of chlamydia in 2007.