TABLE 2—

Numbers of Primary and Secondary Syphilis Cases Among Different Groups, Along With Male–Female Case Ratios: United States, 2000–2003

Year	Total No. of Cases	Cases Among Men	Cases Among Women	Male–Female Case Ratio	Cases Among MSMa	Cases Among Heterosexual Men and Womenb
2000	5973	3528	2445	1.44	441	5532
2001	6100	4132	1968	2.10	1653	4447
2002	6862	5268	1594	3.30	3257	3605
2003	7177	5959	1218	4.89	4424	2753

Note. MSM = men who have sex with men.

^aEstimated by assuming that a male–female case ratio at the 1998 level (1.26) indicates that no primary and secondary syphilis cases occurred among MSM and that the number of cases occurring among MSM can be calculated according to the formula described in the text.

^bCalculated by subtracting estimated cases among MSM from the total number of cases.