Prior to swabbing, a trained photographer took at least 2 photographs of the right eyelid of all participants using a Nikon D-series camera and a Micro Nikon 105 mm; f/2

Prior to swabbing, a trained photographer took at least 2 photographs of the right eyelid of all participants using a Nikon D-series camera and a Micro Nikon 105 mm; f/2.8 lens (Nikon, Tokyo, Japan). multiplex bead assay was used to test for antibodies to two antigens, Pgp3 and CT694. We compared seropositivity to either antigen to clinical signs of active trachoma (trachomatous inflammationfollicular [TF] and trachomatous inflammationintense [TI]) at the individual and cluster NAD 299 hydrochloride (Robalzotan) level, and to ocular chlamydia prevalence at the community level. Results Of 988 children with antibody data, TF prevalence was 7.8% (95% CI 6.1 to 9.5) and TI prevalence was 1.6% (95% CI 0.9 to 2.6). The overall prevalence of antibody positivity to Pgp3 was 27.2% (95% CI 24.5 to 30), and to CT694 was 23.7% (95% CI 21 to 26.2). Ocular chlamydia infection prevalence was 5.2% (95% CI 2.8 to 7.6). Seropositivity to Pgp3 and/or CT694 was significantly associated with TF at the individual and community level and with ocular chlamydia infection and TI at the community level. Older children were more likely to be seropositive than younger children. Conclusion Seropositivity to Pgp3 and CT694 correlates with clinical signs and NAD 299 hydrochloride (Robalzotan) ocular chlamydia infection in a mesoendemic region of Niger. Trial registration ClinicalTrials.gov NCT00792922. Author summary Trachoma programs currently use the clinical sign of trachomatous inflammation-follicular (TF) to guide community treatment decisions and evaluate response to mass drug administration with azithromycin. These programs rely on clinical grading that poorly correlates with infection with the causative agent of trachoma, may provide additional information about exposure and transmission patterns. Here, we evaluated the relationship between serologic markers of (infection in low-prevalence settings [2]. Following MDA, the clinical sign trachomatous inflammationintense (TI) has been shown to correlate better with infection than TF does [3]. However the measurement of clinical signs is subject to inter-grader variability and lack NAD 299 hydrochloride (Robalzotan) of real-time auditing since grading is performed in the field and thus can only later be validated or audited if images are taken. As trachoma elimination programs stand to benefit from an accurate, reproducible assessment of trachoma prevalence, other testing methods may be useful to help guide program decisions. These include tests of infection (polymerase chain reaction [PCR] testing of ocular swabs) and antibody-based testing [4C7]. Antibodies to antigens may act as markers of cumulative exposure to antigens, Pgp3 and CT694, have been shown to be reactive against sera in young children living in trachoma-endemic communities [4,7,8]. At the individual level, antibodies to these proteins demonstrate high sensitivity to ocular infection and high specificity against non-endemic control specimens [8C10]. However, individual associations may not always hold at the community level, and trachoma elimination programs treat ocular infection on a population level. Additionally, as antibody markers are not yet widely used to assess for prevalence, better characterization of how seropositivity compares to other methods of assessing trachoma prevalence is necessary. Here, we evaluate the association between seropositivity, PCR positivity, and clinical signs of active trachoma (TF and TI) at the individual and community level in a region of Niger where some trachoma transmission is occurring (TF prevalence approximately 25% at baseline). Data were collected during the final follow-up visit of the Partnership for the Rapid Elimination of Trachoma (PRET)-Niger trial, in which communities were ELD/OSA1 randomized to receive annual or biannual oral azithromycin for 3 years in order to assess the impact of treatment frequency on ocular chlamydia infection [11]. Methods Study design The study methods have been previously reported in detail elsewhere [11C13]. Briefly, a cluster randomized trial of annual versus biannual mass azithromycin distribution for trachoma control was conducted in the Matameye district of the Zinder region of Niger from May 2010 until August 2013 [4C6]. Data on active trachoma and ocular infection were collected biannually on children aged 0C5 years; dried blood spots for serological analysis were collected only at the 36-month time point and only from children aged 1C5 years. Dried blood spots were shipped to CDC at ambient temperature and tested for antibodies from July to August 2014. Site selection Communities were chosen from among six different catchment areas for primary health care facilities and were eligible for.