Measuring Trachomatous Inflammation-Intense (TI) When Prevalence Is Low Provides Data on Infection With Chlamydia trachomatis

Detección de infección por Chlamydia trachomatis en mujeres sexualmente activas en Venezuela

Introducción.

La infección genital por Chlamydia trachomatis es una de las más frecuentes en el mundo. Cada año se registran cerca de 85 millones de nuevos casos de esta enfermedad, que cursa con graves complicaciones en la mujer y recién nacido.

Objetivo.

Determinar las características clínico-epidemiológicas de la infección por C. trachomatis en mujeres venezolanas sexualmente activas.

Materiales y métodos.

Es un estudio descriptivo, transversal y de campo, sustentado en la historia clínica y el examen físico, la detección de infección con la prueba inmunoenzimática con anticuerpos policlonales anti-LPS y la confirmación de los resultados con la de biología molecular. La muestra estuvo conformada por 100 mujeres sexualmente activas mayores de 12 años de edad, del estado Carabobo, Venezuela.

Resultados.

La mayoría de las mujeres se encontraba entre los 20 y los 45 años de edad. En el 25 % de las mismas, se detectaron anticuerpos IgG anti-C. trachomatis y, en el 84 % de estas, se confirmó la infección mediante PCR; en ninguna de las mujeres se hallaron anticuerpos IgM anti-C. trachomatis.

Conclusión.

La infección crónica predomina en las mujeres entre los 20 y los 45 años de edad; la prueba inmunoenzimática arrojó falsos positivos corroborados por PCR.

The Impact of Image Quality and Trachomatous Inflammation on Using Photography for Trachoma Prevalence Surveys

Purpose

Graded images can be used for trachoma prevalence surveys, but there is concern for mismatch between image and field grades of the upper tarsal conjunctiva. We aimed to determine if poor photograph quality and/or inflammation may contribute to differential grading of trachomatous inflammation—follicular (TF) between field and photograph graders.

Methods

We developed a simplified and expanded image quality grading tool. Agreement was assessed using kappa statistic. We included 5417 eyes with both field and image grades for TF. Eyes where the field and adjudicated photograph TF grades did not match were identified (mismatched) and assigned an image quality (IQ) score and a potential mismatch reason. We also assigned IQ scores to a stratified random sample of 60 eyes with matching field and photograph TF grades (matched).

Results

There were 5240 eyes that had matching grades, whereas 177 eyes (3.3%) were mismatched. Overall quality was high, even in mismatched eyes. There was no difference in overall or specific IQ metrics between eyes with matching grades and eyes with mismatched grades (P = 0.59). Mismatched eyes had worse inflammation compared to matched eyes (P = 0.048). The primary reason for calling TF in the field but not in the photographs appeared to be the number of follicles observed.

Conclusions

Image quality did not explain mismatch between field grades and image grades from this prevalence survey. Inflammation made mismatch more likely.

Translational Relevance

Our quality grading scheme rapidly identifies image quality issues for training. Standardizing TF grading in the presence of inflammation will improve field and photograph grading.

Impact of a single round of mass drug administration with azithromycin on active trachoma and ocular Chlamydia trachomatis prevalence and circulating strains in The Gambia and Senegal

BACKGROUND

Mass drug administration (MDA) with azithromycin is a cornerstone of the trachoma elimination strategy. Although the global prevalence of active trachoma has declined considerably, prevalence persists or even increases in some communities and districts. To increase understanding of MDA impact, we investigated the prevalence of active trachoma and ocular C. trachomatis prevalence, organism load, and circulating strains at baseline and one-year post-MDA in The Gambia and Senegal.

METHODS

Pre- and one-year post-MDA, children aged 0-9 years were examined for clinical signs of trachoma in six Gambian and 12 Senegalese villages. Ocular swabs from each child's right conjunctiva were tested for evidence of ocular C. trachomatis infection and organism load (ompA copy number), and ompA and multi-locus sequence typing (MLST) was performed.

RESULTS

A total of 1171 children were examined at baseline and follow-up in The Gambia. Active trachoma prevalence decreased from 23.9% to 17.7%, whereas ocular C. trachomatis prevalence increased from 3.0% to 3.8%. In Senegal, 1613 and 1771 children were examined at baseline and follow-up, respectively. Active trachoma prevalence decreased from 14.9% to 8.0%, whereas ocular C. trachomatis prevalence increased from 1.8% to 3.6%. Higher organism load was associated with having active trachoma and severe inflammation. Sequence typing demonstrated that all Senegalese samples were genovar A, whereas Gambian samples were a mix of genovars A and B. MLST provided evidence of clustering at village and household levels and demonstrated differences of strain variant frequencies in Senegal, indicative of an "outbreak". MLST, including partial ompA typing, provided greater discriminatory power than complete ompA typing.

CONCLUSIONS

We found that one round of MDA led to an overall decline in active trachoma prevalence but no impact on ocular C. trachomatis infection, with heterogeneity observed between villages studied. This could not be explained by MDA coverage or number of different circulating strains pre- and post-MDA. The poor correlation between active trachoma and infection prevalence supports the need for further work on alternative indicators to clinical signs for diagnosing ocular C. trachomatis infection. MLST typing has potential molecular epidemiology utility, including better understanding of transmission dynamics, although relationship to whole-genome sequence variability requires further exploration.

Community-level Association between Clinical Trachoma and Ocular Chlamydia Infection after MASS Azithromycin Distribution in a Mesoendemic Region of Niger

Purpose: The clinical sign trachomatous inflammation - follicular (TF) is used to monitor indication for and response to mass azithromycin distribution in trachoma-endemic communities. Here, we assess the relationship between TF, trachomatous inflammation - intense (TI), and infection with ocular Chlamydia trachomatis over time during annual mass azithromycin distribution. Methods: We used data from a cluster-randomized trial of mass azithromycin distribution for trachoma control in a mesoendemic region of Niger. This study includes 24 communities that received 3 years of annual mass azithromycin distribution. TF, TI, and ocular chlamydia infection were monitored among children aged 0-5 years. We assessed the correlation between the prevalence of ocular chlamydia infection and 1) TF and 2) TI prevalence over time. Results: At baseline, ocular chlamydia prevalence was 21.2% (95% CI 14.3-28.1%), TF prevalence was 27.7% (95% CI 21.2-34.2%), and TI prevalence was 8.3% (95% CI 5.2-11.5%). The prevalence of all three measures decreased significantly over time (P < 0.001). At baseline, ocular chlamydia infection prevalence was strongly correlated with both TF (rho = 0.78, P < 0.0001) and TI (rho = 0.76, P < 0.0001). The correlation between ocular chlamydia infection and both TF and TI was weak at months 12 and 24. At 36 months, when TF prevalence had dropped below 10%, ocular chlamydia infection and TF were moderately correlated (rho = 0.70, P= 0.0002). Conclusions: Both TF and TI are good indicators of infection prevalence prior to mass azithromycin distribution. However, this relationship may be affected by repeated rounds of mass azithromycin distribution.

Community-level chlamydial serology for assessing trachoma elimination in trachoma-endemic Niger

BACKGROUND

Program decision-making for trachoma elimination currently relies on conjunctival clinical signs. Antibody tests may provide additional information on the epidemiology of trachoma, particularly in regions where it is disappearing or elimination targets have been met.

METHODS

A cluster-randomized trial of mass azithromycin distribution strategies for trachoma elimination was conducted over three years in a mesoendemic region of Niger. Dried blood spots were collected from a random sample of children aged 1-5 years in each of 24 study communities at 36 months after initiation of the intervention. A multiplex bead assay was used to test for antibodies to two Chlamydia trachomatis antigens, Pgp3 and CT694. We compared seropositivity to either antigen to clinical signs of active trachoma (trachomatous inflammation-follicular [TF] and trachomatous inflammation-intense [TI]) at the individual and cluster 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 ocular chlamydia infection in a mesoendemic region of Niger.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00792922.