Development and evaluation of screening strategies for Chlamydia trachomatis infections in an STD clinic

Comparative model-based analysis of screening programs for Chlamydia trachomatis infections

The design of a screening program for asymptomatic genital infections with Chlamydia trachomatis, requires decisions about which sex or age group should be targeted and whether partner referral should be included in the program. To investigate the effects of various screening programs on the prevalence and incidence of asymptomatic C. trachomatis infections in women, in May 1996 to April 1997 in Bilthoven, the Netherlands, the authors used a stochastic simulation model for C. trachomatis transmission in an age-structured, heterosexual population with a sexually highly active core group. Different screening scenarios were implemented over a time period of 10 years. Prevalence, incidence, and the fraction of infected persons found by partner referral were computed. Through screening of men and women between ages 15 and 24 years (baseline scenario), the prevalence of asymptomatic infections in women could be reduced from 4.2% to 1.4% in 10 years. Increasing the age range of screening up to ages 29 or 34 years led to prevalences of 0.4% and 0.06%, respectively, after 10 years. About 28% of all infected persons were found via partner referral. There are considerable indirect positive effects of screening on those population groups that are not included in the screening because of the reduced risk of becoming infected. Partner referral contributes substantially to prevalence reduction.

Patient referral outcome in gonorrhoea and chlamydial infections

OBJECTIVE

To describe the outcome of patient referral at the STD clinic of the University Hospital Rotterdam. To study characteristics of heterosexual index patients and partnerships related to referral outcome.

METHODS

In 1994, patients with gonorrhoea and chlamydia were referred to public health nurses for interview and patient referral. Referral outcome was classified as "verified" if partners attended the STD clinic and as "believed" if partners were said to have attended elsewhere.

RESULTS

Of 454 patients, 250 (55%) participated in the study. The outcome of patient referral for the 502 eligible partners was 103 (20.5%) verified referrals, 102 (20%) believed referrals, and 297 (59%) with unknown follow up. Of the 103 partners examined, 43 had an STD of which 63% reported no symptoms. The contact finding ratio was higher for chlamydia patients and heterosexual men. Also, referral was more effective for index patients with recent sexual contact, with follow up visits to the public health nurse, for men who were not commercial sex worker (CSW) clients, and, to a lesser degree, for Dutch patients and patients who sometimes used condoms. For steady partners, referral was improved if the last sexual contact was more recent. Casual partners visited the clinic more often if sexual contact occurred more than once, if the last contact was more recent, if they were older, and if they were Dutch.

CONCLUSIONS

Patient referral was more effective for certain groups, such as chlamydia patients and steady partners, but was inadequate for others, including CSW and their clients, other "one night stands", young partners, and ethnic minorities.

Noninvasive screening for genital chlamydial infections in asymptomatic men: Strategies and costs using a urine PCR assay

OBJECTIVE

To evaluate cost saving strategies to screen for genital chlamydial infection in men using polymerase chain reaction (PCR) technology.

METHODS

Men with no urethral symptoms presenting to a sexually transmitted disease (STD) clinic were recruited. Study participants underwent a questionnaire interview. Urethral swabs were taken to perform a smear for polymorphonuclear leucocytes (PMN) and for the detection of Chlamydia trachomatis by culture and PCR. First-catch urine was collected for a leukocyte esterase test (LET) and PCR.

RESULTS

C trachomatis infection was detected in 36 of 463 (7.8%) men. LET and PMN were positive in 10 (28%) and 12 (33%) infected men, respectively. Risk factors for chlamydial infection were younger than age 25 years, LET-positive, PMN-positive and STD contact (P<0.001). The direct cost of genital chlamydial infection in men in Canada has been previously estimated at $381/case. Based on a sensitivity of 90% for urine PCR, the estimated direct cost of testing all participants to detect 32 cases was $453/case. Using risk factors recommended in the Canadian STD Guidelines (age younger than 25 years, new partner, STD contact or unprotected sex), the same number of cases would have been detected by testing only 384 men at $376/case. Using age younger than 25 years or STD contact as the screening criterion, 78% of those infected would have been detected at $259/case, and no new cases would have been detected by adding LET-positive or PMN-positive as risk factors.

CONCLUSION

Targeted screening for chlamydial infection using urine PCR assay and risk factors recommended in the Canadian guidelines could substantially reduce the cost of screening at a STD clinic setting. LET and PMN smear did not appear to be useful indicators of chlamydial infection in this population.

Differences in clinical manifestations of genital chlamydial infections related to serovars

OBJECTIVES

To study the association of serovars of Chlamydia trachomatis with clinical manifestations of genital tract infection and socio-demographic characteristics.

METHODS

In 1986-88 the C trachomatis isolates from 159 heterosexual men and 116 women attending a sexually transmitted disease (STD) clinic were collected and typed accordingly. A medical history was recorded, a physical examination took place and samples were taken for laboratory diagnostics.

RESULTS

Serovars E, F and D were the most common for both men (75%) and women (67%). Men infected with serovars of the C-complex had more often a history of STD (p = 0.06). The opposite was demonstrated in women (p = 0.07). In addition, women younger than 18 years at first intercourse were more often infected with C-complex serovars (p = 0.05). For men, the serovars F/G less often produced symptoms of urethral discharge (p = 0.01) than the serovars of the B-complex and C-complex and were less often associated with the presence of 10 or more leukocytes in a Gram-stained smear (p = 0.04).

CONCLUSIONS

In this study, infections with serovars F and G caused less obvious symptoms and signs of inflammation in men; in women no differences were found in the clinical manifestation of infections with different serovars.