2 figures, 1 table omitted
During 1998-2002, the STD/HIV Prevention and Care Program of the Chicago
Department of Public Health (CDPH) recorded 1,582 cases of primary and secondary
(P&S) syphilis, the most of any U.S. city.1 Although
case numbers and overall rates remained stable in Chicago during this period,
patterns of transmission changed substantially. Throughout most of the 1990s,
P&S syphilis was reported almost exclusively among heterosexuals. During
1998-2000, however, men who have sex with men (MSM) accounted for approximately
15% of Chicago’s P&S syphilis morbidity. Since 2001, MSM have accounted
for nearly 60% of patients with P&S syphilis. During 2000-2002, CDPH conducted
interviews with persons with syphilis; some MSM reported they had engaged
in only oral sex and were surprised to have acquired syphilis. In response,
CDPH began collecting information on oral sex from persons with syphilis.
To assess the role of oral sex in the transmission of P&S syphilis in
Chicago, CDPH analyzed surveillance data and interview responses. This report
summarizes the results of these analyses, which suggested that a substantial
proportion (13.7%) of syphilis cases were attributed to oral sex, particularly
among MSM. Persons who are not in a long-term monogamous relationship and
who engage in oral sex should use barrier protection (e.g., male condoms or
other barrier methods) to reduce the risk for sexually transmitted disease
CDPH staff interviewed persons with syphilis to ensure adequacy of treatment
for patients and their sex partners and to provide STD/human immunodeficiency
virus (HIV) education and other testing and treatment services. Interviewers
obtained demographic data (i.e., sex, age, race/ethnicity, and sexual orientation)
and risk-behavior information (i.e., sexual behavior, number and sex of sex
partners, venues for meeting partners, and self-reported HIV status). During
the interviews, CDPH staff determined whether oral sex was the only sexual
exposure the patient reported during the period of syphilis acquisition. Persons
were asked about the type of sexual contact during the interval in which they
likely acquired syphilis. This period usually is considered to be 3 months
before treatment for primary syphilis and 6 months for secondary syphilis.
During 1998-2002, the number of reported cases of P&S syphilis in
Chicago ranged from 338 to 353 cases annually; overall rates per 100,000 population
ranged from 11.8 to 12.2. Rates declined 68% among women, from 9.2 to 2.9,
and increased 50% among men, from 14.7 to 22.1. Of the 1,582 persons with
P&S syphilis, 948 (60%) were heterosexuals, and 524 (33%) were MSM. Approximately
90% of heterosexuals were non-Hispanic black. An estimated 54% of MSM were
non-Hispanic white, 26% were non-Hispanic black, and 13% were Hispanic. Rates
declined by 31% among non-Hispanic black men and by 67% among non-Hispanic
black, non-Hispanic white, and Hispanic women; rates increased among non-Hispanic
white and Hispanic men (469% and 462%, respectively).
HIV-infection rates for persons with syphilis varied by sex and sexual
orientation. In 2001 and 2002, among persons with P&S syphilis, less than
10% of heterosexuals and approximately half of MSM were HIV infected.
During 2000-2002, of 962 persons with P&S syphilis, data were available
for 627 (65.2%); 325 (51.8%) were MSM, 157 (25.0%) were heterosexual men,
and 145 (23.1%) were heterosexual women. Overall, 86 (13.7%) persons indicated
that oral sex was their only sexual exposure during the period they likely
acquired syphilis: 66 (20.3%) of 325 MSM, 10 (6.4%) of 157 heterosexual men,
and 10 (6.9%) of 145 heterosexual women (p<0.0001).
During the period of syphilis acquisition among the 325 MSM, oral sex
was the only sexual exposure reported by 18 (22.7%) of 79 with primary syphilis,
48 (19.5%) of 246 with secondary syphilis, 36 (21.6%) of 167 with HIV infection,
nine (19.6%) of 46 without HIV infection, and 21 (18.7%) of 112 with unknown
HIV status. Thirty-three (17.2%) of 192 non-Hispanic white MSM, 16 (30.2%)
of 53 Hispanic MSM, and 14 (19.4%) of 72 non-Hispanic black MSM reported having
only oral sex during the period in which they likely acquired syphilis. When
compared with heterosexual men and women, respectively, MSM were 3.8 and 3.4
times more likely to report only oral sex during the period of syphilis acquisition.
C Ciesielski, MD, I Tabidze, MD, C Brown, MBA, Chicago Dept of Public
Health, Illinois. Div of Sexually Transmitted Diseases Prevention, National
Center for HIV, STD, and TB Prevention, CDC.
The findings in this report suggest that during 2000-2002, 13.7% of
P&S syphilis cases in Chicago were attributed to oral sex, including 20.3%
of cases among MSM. Other reports also have associated oral sex with transmission
of syphilis2; one third of MSM who were involved
in syphilis outbreaks in Brighton and Manchester, United Kingdom, acquired
syphilis through oral sex.3 Syphilitic lesions
develop at the site of syphilis infection within 10-90 days (median: 21 days),
and lesions on the lips, tongue, and oral mucosa have been commonly described.
During the secondary stage of syphilis, mucous patches, which have high concentrations
of Treponema pallidum and are extremely infectious,
might develop in the mouth. Syphilis in the oral cavity often is asymptomatic
or subclinical and can be mistaken by patients for apthous ulcers or herpes,
thereby delaying curative treatment and allowing ongoing transmission.
Because the risk for HIV transmission through oral sex is much lower
than the risk through anal or vaginal sex,4 persons
might mistakenly consider unprotected oral sex (i.e., without a condom) to
be a safe or no-risk sexual practice and adopt oral sex as a replacement for
higher-risk behaviors. Condoms rarely are used for oral sex. Of an estimated
1,000 MSM in Chicago who stated that they had engaged in oral sex during the
preceding 60 days, more than 75% never used condoms for either oral insertive
or oral receptive sex (CDPH, unpublished data, 2003). Oral syphilitic lesions
disrupt the protective epithelial barrier and recruit HIV target cells, increasing
the risk for HIV transmission.5 Although oral
sex might carry a lower risk for transmitting HIV than other forms of sex,
repeated unprotected exposures, especially in the presence of syphilitic lesions,
represent a substantial risk for HIV transmission. Syphilis might also increase
progression of HIV disease.6,7
The findings in this report are subject to at least one limitation.
The data might underestimate the role of oral sex in syphilis transmission
because most persons who reported engaging in anal and vaginal sex also reported
engaging in oral sex. Transmission was attributed to oral sex in only the
14% of cases in which oral sex was the only sexual exposure reported during
the interval when syphilis likely was acquired.
Some men who engaged in only oral sex believed that they were practicing
safe sex and were surprised when they received a syphilis diagnosis. These
data underscore the need for educating sexually active persons regarding the
risk for syphilis transmission through oral sex. That syphilis might hasten
the progression of HIV disease should provide a further motivation for MSM,
especially HIV-infected MSM, to avoid syphilis acquisition. Persons who are
not in a long-term monogamous relationship and who engage in oral sex should
use barrier protection (e.g., male condoms or other barrier methods) to reduce
the risk for STD and HIV transmission.
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