Characterizing trachoma elimination using serology

Area of Science:

• Ophthalmology
• Infectious Disease Epidemiology
• Public Health

Background:

• Trachoma elimination is a global public health priority by 2030.
• Serological IgG antibody measurements in children are being explored for surveillance.
• Lack of programmatic guidelines for serology hinders effective disease elimination strategies.

Purpose of the Study:

• To develop a novel serological approach for estimating Chlamydia trachomatis transmission.
• To establish evidence-based thresholds for seroconversion rates (SCRs) to guide trachoma control decisions.
• To inform programmatic decision-making for global trachoma elimination.

Main Methods:

• Collation of Chlamydia trachomatis Pgp3 and CT694 IgG measurements from 48 serosurveys.
• Analysis of data from 41,168 children aged 1-5 years across Africa, Latin America, and the Pacific Islands.
• Development of a probabilistic model to estimate transmission levels relative to intervention needs.

Main Results:

• Proposed SCR thresholds for halting control measures (>90% certainty) at ≤2.2 per 100 person-years.
• Proposed SCR thresholds indicating need for continued interventions (>90% certainty) at ≥4.5 per 100 person-years.
• Demonstrated that more extreme SCR thresholds increase confidence in elimination or need for action.

Conclusions:

• Trachoma serosurveys provide a robust method for guiding elimination program decisions.
• Established SCR thresholds offer objective criteria for programmatic action.
• This approach supports the global goal of trachoma elimination as a public health problem.