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Session 18 Oral Abstracts and Mini-Lectures
Epidemiology of HIV Infection in the United States
Tuesday, 10 am - 12:30 pm
Presentation Time: 11:15 am
Room 2005


88
Trends in Primary and Secondary Syphilis and HIV Seroincidence among Men Who Have Sex with Men in San Francisco, 1998-2002
K Buchacz*1, T Kellogg2, W McFarland2, R Kohn3, J Dilley4, B Louie2, C Kent3, S Holmberg1, and J Klausner3
1CDC, Atlanta, GA, USA; 2San Francisco Dept. of Publ. Hlth., CA, USA; 3STD Prevention and Control Svcs., City and County of San Francisco, CA, USA; and 4AIDS Hlth. Project, San Francisco, CA, USA

Background:  Syphilis facilitates the acquisition and transmission of HIV infection. To explore whether the current syphilis epidemic has been associated with increases in HIV incidence in San Francisco, we examined trends in HIV incidence in men who have sex with men (MSM) in 2 HIV testing populations and rates of primary and secondary syphilis among an estimated 50,782 MSM in the city from 1998 through 2002.

Methods:  We reviewed city sexually transmitted disease (STD) morbidity data. We determined HIV incidence by applying a sensitive/less sensitive testing algorithm to HIV-seropositive blood samples of MSM seeking HIV testing at the San Francisco City STD Clinic (SFCC) and at anonymous testing sites of the AIDS Health Project (AHP).

Results:  Primary and secondary syphilis rates increased more than 1000% from 1998 to 2002 (Table). HIV incidence was highest in 1999 and then tended to decline through 2002 at both sites (c2 test for trend, p = 0.13 for AHP, p = 0.36 for SFCC). At SFCC, however, HIV incidence was elevated in 2002 compared with 2001 (p = 0.12).

 

Primary and Secondary Syphilis Rates and HIV Incidence

 

Primary and Secondary Syphilis Cases

MSM HIV Testing at AHP

MSM HIV Testing at SFCC

Year

Rate per 100,000

N*

n†

HIV Incidence (%) and 95% CI

N*

n†

HIV Incidence (%) and 95% CI

1998

8

2726

23

1.86 (0.99 - 2.72)

791

17

4.83 (2.21 - 7.46)

1999

26

1598

28

3.91 (2.25 - 5.56)

868

21

5.44 (2.78 - 8.09)

2000

71

1721

21

2.68 (1.37 - 3.99)

1324

20

3.34 (1.67 - 5.02)

2001

223

1762

22

2.76 (1.44 - 4.08)

1274

14

2.46 (0.99 - 3.93)

2002

512

1280

14

2.41 (0.97 - 3.85)

1544

28

4.03 (2.32 - 5.74)

* N = number of HIV testers. †n = number with incident HIV-infection.

 

The MSM who HIV tested at AHP and SFCC were similar demographically. In 2002, their median age was 33 years; 65% were white, 15% Hispanic/Latino, 13% Asian/Pacific Islander, and 5% African American. The 42 MSM with incident HIV infection in 2002 had a median age of 32 years; 23 (55%) were white and 12 (29%) Hispanic/Latino. Of the 260 syphilis patients in 2002, 65% were HIV+. The 85 who were HIV- had a median age of 36 years; 58 (68%) were white and 10 (12%) Hispanic/Latino.

Conclusions:  To date, we detected no marked increases in HIV incidence among MSM in 2 HIV-testing populations, concurrent with the syphilis outbreak in San Francisco. However, changes over time in characteristics and volume of MSM testing in these 2 settings may distort possible inferences about HIV incidence trends among all MSM in San Francisco. Integrated HIV/STD prevention programs for MSM in San Francisco are needed to stop the spread of syphilis and potential increases in HIV infections.

Keywords: HIV incidence; Syphilis; MSM