Anal Lymphogranuloma Venereum Infection Screening With IgA Anti-Chlamydia trachomatis-Specific Major Outer Membrane Protein Serology

Background: Anal lymphogranuloma venereum (LGV) infections, caused by Chlamydia trachomatis biovar L (Ct+/LGV+), are endemic among men who have sex with men (MSM). Anal non-LGV biovar Ct infections (Ct+/LGV-) can be eradicated with 1 week doxycycline, whereas Ct+/LGV+ infections require 3-week doxycycline. To differentiate Ct+/LGV+ from Ct+/LGV- infections, biovar-specific Nucleic Acid Amplification Test (NAAT) are standard, but also expensive and laborious. A chlamydia-specific serological assay could serve as an alternative test. Methods: MSM were screened for anal Ct+/LGV+ and Ct+/LGV- infections with a commercial nonspecific NAAT and an in house biovar L-specific NAAT. Serum samples were evaluated with chlamydia-specific anti-Major Outer Membrane Protein (MOMP) and antilipopolysaccharide assays of IgA and IgG classes. Asymptomatic patients were identified as: (1) no anal complaints or (2) no microscopic inflammation (i.e., <10 leucocytes per high power field in anal smears). The best differentiating assay was subsequently evaluated in 100 Ct+/LGV+ and 100 Ct +/LGV- MSM using different cut-off points. Results: The anti-MOMP IgA assay was the most accurate to differentiate Ct+/LGV+ (n = 42) from Ct+/LGV+ (n = 19) with 85.7% sensitivity (95% confidence interval [CI], 72.2-93.3) and 84.2% specificity (95% CI, 62.4-94.5), even among asymptomatic patients. In a population comprising 98 Ct+/LGV+ and 105 Ct+/LGV- patients, the anti-MOMP IgA assay scored most accurate when the cut-off point was set to 2.0 with 75.5% (95% CI, 65.8-83.6) sensitivity and 74.3% (95% CI, 64.8-82.3) specificity. Conclusions: The IgA anti-MOMP assay can identify a considerable proportion of the (asymptomatic) anal LGV infections correctly. Yet, biovar L-specific NAAT are still the preferred diagnostic tests in clinical setting

Effectiveness of yearly, register based screening for chlamydia in the Netherlands: controlled trial with randomised stepped wedge implementation

To evaluate the effectiveness of register based, yearly chlamydia screening

Who participates in the Dutch Chlamydia screening? A study on demographic and behavioral correlates of participation and positivity

In the Netherlands, an Internet-based Chlamydia Screening Implementation was initiated in 3 regions, aiming to reduce population prevalence by annual testing and treatment of people aged 16 to 29 years. We studied who was reached in the first screening round by relating participation and chlamydia positivity to sociodemographic and sexual risk factors. Data from the 2008/2009 screening round were analyzed (261,025 screening invitations, 41,638 participants). Participation rates were adjusted for the sexually active population. Sociodemographic and behavioral correlates of screening participation and positivity were studied by (multilevel) logistic regression models. The overall adjusted participation rate in the first screening round was 19.5% (95% confidence interval, 19.4-19.7) among sexually active people (women, 25%; men, 13%). Sociodemographic factors associated with lower participation were male gender (odds ratio [OR], male 1 vs. female 1.8), young age (OR, 16-19 1 vs. older groups 1.7-2.1), non-Dutch origin (OR between 0.7-0.9), lower education (OR, low 1 vs. high 1.4), high community risk level (0.8), and low socioeconomic status (0.9). Behavioral factors associated with lower participation were a long-standing relationship (0.7) and no reported history or symptoms of sexually transmitted infections (no symptoms, 0.4-0.6) . Factors most strongly related to higher Ct positivity were young age (OR, 1 vs. older groups 0.5-0.8), non-Dutch origin (1.4-2.8), non-Dutch steady partner (1.9-2.7), residence in a high-risk area (1.4-1.5), lower education (high, 0.3-0.5), and a history or symptoms of sexually transmitted infection (no symptoms, 0.4-0.6). Sociodemographic factors associated with lower participation were also associated with higher Ct positivity, showing that high-risk demographic groups are more difficult to mobilize than low-risk groups. Independent of this, higher behavioral risk levels were associated with higher participation rates, suggesting self-selection for screening based on the persons' risk (perception) in both low- and high community risk groups. Our study shows the complexity of the process, including individual and community factors that also interact, when screening for chlamydi

Systematic selection of screening participants by risk score in a Chlamydia screening programme is feasible and effective

Systematic screening for Chlamydia trachomatis by individual invitation can be optimised by filtering participants on risk profile, excluding people at no or low risk. The authors investigated this technique in a large-scale chlamydia screening programme in The Netherlands in one rural region where relatively low prevalence was expected ( <2%). Invitees were alerted by personal letter to log in to http://www.chlamydiatest.nl and fill in an 8-item questionnaire. Only invitees with sufficient score could proceed to request a test kit. The authors investigated the effect of selection on participation, positivity and acceptability in three screening rounds and on the number needed to invite and the number needed to screen. The selection led to exclusion of 36% of potential participants and a positivity rate of 4.8% among participants, achieving similar number needed to screen values in the rural and urban areas. Higher scores were clearly related to higher positivity rates. Persons who were excluded from participation did not have a lower response in the next round. The acceptability study revealed disappointment about exclusion of 30% of excluded participants but most approved of the screening set-up. Systematic selection of screening participants by risk score is feasible and successful in realising higher positivity rates. A somewhat stricter selection could be applied in the rural and urban areas of the screening programme. Multiple-item selection with a cut-off total score may work better than, more commonly used, selection by single criteria, especially in low-risk populations. Acceptability of selection is high but could still be improved by better communication on expectation

Modelling the impact of chlamydia screening on the transmission of HIV among men who have sex with men

<p>Background: Recent studies have found high prevalences of asymptomatic rectal chlamydia among HIV-infected men who have sex with men (MSM). Chlamydia could increase the infectivity of HIV and the susceptibility to HIV infection. We investigate the role of chlamydia in the spread of HIV among MSM and the possible impact of routine chlamydia screening among HIV-infected MSM at HIV treatment centres on the incidence of chlamydia and HIV in the overall MSM population.</p><p>Methods: A mathematical model was developed to describe the transmission of HIV and chlamydia among MSM. Parameters relating to sexual behaviour were estimated from data from the Amsterdam Cohort Study among MSM. Uncertainty analysis was carried out for model parameters without confident estimates. The effects of different screening strategies for chlamydia were investigated.</p><p>Results: Among all new HIV infections in MSM, 15% can be attributed to chlamydia infection. Introduction of routine chlamydia screening every six months among HIV-infected MSM during regular HIV consultations can reduce the incidence of both infections among MSM: after 10 years, the relative percentage reduction in chlamydia incidence would be 15% and in HIV incidence 4%, compared to the current situation. Chlamydia screening is more effective in reducing HIV incidence with more frequent screening and with higher participation of the most risky MSM in the screening program.</p><p>Conclusions: Chlamydia infection could contribute to the transmission of HIV among MSM. Preventive measures reducing chlamydia prevalence, such as routine chlamydia screening of HIV-infected MSM, can result in a decline in the incidence of chlamydia and HIV.</p>