Trachoma, Anti-Pgp3 Serology, and Ocular Chlamydia trachomatis Infection in Papua New Guinea.

BACKGROUND: In Melanesia, the prevalence of trachomatous inflammation-follicular (TF) suggests that public health-level interventions against active trachoma are needed. However, the prevalence of trachomatous trichiasis is below the threshold for elimination as a public health problem and evidence of conjunctival infection with trachoma's causative organism (Chlamydia trachomatis [CT]) is rare. Here, we examine the prevalence of ocular infection with CT and previous exposure to CT in three evaluation units (EUs) of Papua New Guinea. METHODS: All individuals aged 1-9 years who were examined for clinical signs of trachoma in 3 Global Trachoma Mapping Project EUs were eligible to take part in this study (N = 3181). Conjunctival swabs were collected from 349 children with TF and tested by polymerase chain reaction to assess for ocular CT infection. Dried blood spots were collected from 2572 children and tested for anti-Pgp3 antibodies using a multiplex assay. RESULTS: The proportion of children with TF who had CT infection was low across all 3 EUs (overall 2%). Anti-Pgp3 seroprevalence was 5.2% overall and there was no association between anti-Pgp3 antibody level and presence of TF. In 2 EUs, age-specific seroprevalence did not increase significantly with increasing age in the 1- to 9-year-old population. In the third EU, there was a statistically significant change with age but the overall seroprevalence and peak age-specific seroprevalence was very low. CONCLUSIONS: Based on these results, together with similar findings from the Solomon Islands and Vanuatu, the use of TF to guide antibiotic mass drug administration decisions in Melanesia should be reviewed.

Population-Based Trachoma Mapping in Six Evaluation Units of Papua New Guinea.

PURPOSE: We sought to determine the prevalence of trachomatous inflammation - follicular (TF) in children aged 1-9 years, and trachomatous trichiasis (TT) in those aged ≥15 years, in suspected trachoma-endemic areas of Papua New Guinea (PNG). METHODS: We carried out six population-based prevalence surveys using the protocol developed as part of the Global Trachoma Mapping Project. RESULTS: A total of 19,013 individuals were sampled for inclusion, with 15,641 (82.3%) consenting to participate. Four evaluation units had prevalences of TF in children ≥10%, above which threshold the World Health Organization (WHO) recommends mass drug administration (MDA) of azithromycin for at least three years; Western Province (South Fly/Daru) 11.2% (95% confidence interval, CI, 6.9-17.0%), Southern Highlands (East) 12.2% (95% CI 9.6-15.0%), Southern Highlands (West) 11.7% (95% CI 8.5-15.3%), and West New Britain 11.4% (95% CI 8.7-13.9%). TF prevalence was 5.0-9.9% in Madang (9.4%, 95% CI 6.1-13.0%) and National Capital District (6.0%. 95% CI 3.2-9.1%) where consideration of a single round of MDA is warranted. Cases of TT were not found outside West New Britain, in which four cases were seen, generating an estimated population-level prevalence of TT in adults of 0.10% (95% CI 0.00-0.40%) for West New Britain, below the WHO elimination threshold of 0.2% of those aged ≥15 years. CONCLUSION: Trachoma is a public health issue in PNG. However, other than in West New Britain, there are few data to support the idea that trachoma is a cause of blindness in PNG. Further research is needed to understand the stimulus for the active trachoma phenotype in these populations.