Shigellosis linked to sex venues, Australia - Dispatches

Emerging Infectious Diseases, August, 2002 by Belinda O'Sullivan, Valerie Delpech, Giulietta Pontivivo, Thomas Karagiannis, Debbie Marriott, John Harkness, Jeremy M. McAnulty

Given the variability of standard infection-control practices across sex venues, Shigella may have been transmitted either directly during casual sex or indirectly from contact with contaminated surfaces or douching equipment. While visiting a sex venue was the only significant risk factor associated with shigellosis, 40% of patients reported not having attended a sex venue. Other factors that we did not measure may have led to transmission in these persons, including casual or sexual contact with other people with shigellosis outside sex venues, contact with fomites, or eating contaminated food. The food-borne route is unlikely, as this outbreak did not affect the general community.

Despite active surveillance, some underreporting of cases is likely in this outbreak because not all patients would have consulted a physician or had a fecal specimen obtained. However, the rate of physician visits for shigellosis is likely to be higher than for other less severe diarrheal illnesses (12). While the use of historical controls makes evaluating food- and waterborne risk factors for shigellosis difficult, we believe that the evaluation of sexual behaviors in homosexuals is likely to be reliable as they show little variation over the study period (13).

An interagency approach was used to develop and conduct plans to control the outbreak. Actions included a health promotion campaign focused on homosexual men; a shigellosis forum attended by owners, managers, and cleaners of sex venues; and the interagency development of infection control guidelines for such establishments. Guidelines for infection control should be followed and equipment and surfaces in sex venues should be cleaned regularly in adequate lighting. Patrons should have easy access to and be encouraged to use hand-washing facilities to minimize the likelihood of transmission of enteric pathogens. Homosexual men should routinely be given information about the ongoing risk of transmission of enteric pathogens.

Table. Characteristics of shigellosis patients and controls,
New South Wales, Australia, April 1-July 31, 2000

                                            Patients   Controls
                                            N=42 (%)   N=65 (%)

Casual sex partners in the last 3 months    37 (88)    46 (71)
Visited a sex venue in the last 3 months    31 (74)    28 (43)
Visited a sex venue in the last 2 weeks     24 (57)    14 (22)
More than one sex partner in the last 2     21 (50)    21 (32)
  weeks
Any sex in the 2 weeks before onset of      37 (88)    52 (80)
  illness (c)
Oral receptive sex in the last 2            35 (83)    48 (74)
  weeks (d)
Anal insertive sex in the last 2            26 (62)    32 (49)
  weeks (d)
Anal receptive sex in the last 2            25 (60)    28 (43)
  weeks (d)
Oral-anal insertive sex in the last 2       13 (31)    22 (34)
  weeks (d)
Digital insertive sex in the last 2         26 (62)    31 (48)
  weeks (d)
Not always washing hands after sex in       16 (38)    19 (29)
  the last 2 weeks
Dined out at a commercial food outlet (c)   25 (60)    27 (42)
  in the last 3 days before onset of
  illness
Traveled overseas in the last 3 months       9 (24)    12 (18)
HIV positive                                22 (52)    31 (48)

                                              Crude odds ratio
                                                (95% CI (a))

Casual sex partners in the last 3 months    3.1 (1.0 to 9.0) (b)
Visited a sex venue in the last 3 months    3.6 (1.6 to 8.5) (b)
Visited a sex venue in the last 2 weeks     4.8 (2.1 to 11.4) (b)
More than one sex partner in the last 2     3.1 (1.3 to 7.5) (b)
  weeks
Any sex in the 2 weeks before onset of           Incalc (d)
  illness (c)
Oral receptive sex in the last 2              1.8 (0.7 to 4.7)
  weeks (d)
Anal insertive sex in the last 2              1.7 (0.8 to 3.7)
  weeks (d)
Anal receptive sex in the last 2              1.9 (0.9 to 4.3)
  weeks (d)
Oral-anal insertive sex in the last 2         0.9 (0.4 to 2.0)
  weeks (d)
Digital insertive sex in the last 2           1.8 (0.8 to 3.9)
  weeks (d)
Not always washing hands after sex in         1.4 (0.6 to 3.2)
  the last 2 weeks
Dined out at a commercial food outlet (c)   2.5 (1.1 to 5.8) (b)
  in the last 3 days before onset of
  illness
Traveled overseas in the last 3 months        1.3 (0.5 to 3.4)
HIV positive                                  1.2 (0.6 to 2.6)

(a) 95% CI, 95% confidence intervals.

(b) Significant at p<0.05

(c) For controls, this question was asked in relation to previous
2 weeks rather than the 2 weeks before onset of illness.

(d) Missing values were excluded from the analysis except for sexual
activity variables (e.g., oral insertive sex), for which participants
were asked to indicate "yes" if they did the specified activity.
As such, failure to answer these questions was considered a "no"
response.