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

Abstract

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.

Discord between presence of follicular conjunctivitis and Chlamydia trachomatis infection in a single Torres Strait Island community: a cross‐sectional survey

“…In the Torres Strait, the absence of C. trachomatis by PCR makes other unidentified viral or allergic causes the more likely precipitants for the follicular conjunctivitis consistent with TF found. Our results resemble those reported in the Melanesian nations of PNG, Solomon Islands, and Vanuatu where the prevalence of TF is high in children, but ocular C. trachomatis infection is uncommon and TT is rarely seen in adults 29–32 . Follow‐up surveys in the Solomon Islands found a range of non‐chlamydial pathogens detected in individuals with TF but, as with our study, a single dominant aetiology to explain prevalent TF was unable to be identified 33 .…”

“…The high prevalence of TF, together with the absence of TI in children and lack of TT in adults, paints a conflicting clinical picture of the public health threat posed by trachoma in this community. The valuable insights gained through laboratory testing and detailed clinical examination performed by an ophthalmologist suggests that trachoma [29][30][31][32] Follow-up surveys in the Solomon Islands found a range of nonchlamydial pathogens detected in individuals with TF but, as with our study, a single dominant aetiology to explain prevalent TF was unable to be identified. 33 Future options for work in the Torres Strait could include using metagenomic deep sequencing for the identification of unexpected pathogens.…”

“…The findings of our study add to the growing body of evidence suggesting that in settings where there are high rates of TF and low rates of TT, programmatic decision-making should not rely solely on the prevalence of clinical signs identified using the WHO simplified grading system. 15,16,29,30 The results reported in this paper have been reviewed by Australia's national Trachoma Surveillance and Control Reference Group.…”

A national survey integrating clinical, laboratory, and WASH data to determine the typology of trachoma in Nauru

“…Whilst results could not be used as a prevalence estimate for programmatic planning, the findings did suggest that active trachoma may be a public health problem and provided justification for further investigation [ 11 ]. Subsequent population-based surveys in the neighbouring countries of Papua New Guinea (PNG), Solomon Islands, and Vanuatu had similar findings [ 12 – 15 ]. Additionally, there was little indication in those countries of current C .…”

“…trachomatis infection in children, based on polymerase chain reaction (PCR) detection on conjunctival swabs, or past infection based on antibodies to the C . trachomatis antigen Pgp3 [ 12 , 15 – 17 ]. It was therefore hypothesised that in these three Melanesian nations, as-yet undetermined aetiologies may be responsible for much of the clinical syndrome that is phenotypically indistinguishable from TF, a phenomenon referred to as the “Pacific enigma” [ 16 ].…”