Structural Uncertainty in Onchocerciasis Transmission Models Influences the Estimation of Elimination Thresholds and Selection of Age Groups for Seromonitoring. (16th March 2020)

• Record Type: Journal Article
• Authors: Hamley, Jonathan I D; Walker, Martin; Coffeng, Luc E; Milton, Philip; de Vlas, Sake J; Stolk, Wilma A; Basáñez, Maria-Gloria
• Is Part Of: Journal of infectious diseases. Volume 221(2020)Supplement 5
• Page Start: S510
• Page End: S518
• Publication Date: 2020-03-16
• Subjects: onchocerciasis -- Ov16 serology -- receiver operating characteristic curve -- age-dependent exposure -- density dependence -- elimination -- threshold -- positive predictive value -- ivermectin -- microfilarial prevalence; Communicable diseases -- Periodicals; Diseases -- Causes and theories of causation -- Periodicals; Medicine -- Periodicals; Communicable Diseases -- Periodicals; Electronic journals; 616.9
• DOI: 10.1093/infdis/jiz674
• Languages: English
• ISSNs: 0022-1899

Abstract

Abstract: Background: The World Health Organization recommends monitoring Onchocerca volvulus Ov16 serology in children aged <10 years for stopping mass ivermectin administration. Transmission models can help to identify the most informative age groups for serological monitoring and investigate the discriminatory power of serology-based elimination thresholds. Model predictions depend on assumed age-exposure patterns and transmission efficiency at low infection levels. Methods: The individual-based transmission model, EPIONCHO-IBM, was used to assess (1) the most informative age groups for serological monitoring using receiver operating characteristic curves for different elimination thresholds under various age-dependent exposure assumptions, including those of ONCHOSIM (another widely used model), and (2) the influence of within-human density-dependent parasite establishment (included in EPIONCHO-IBM but not ONCHOSIM) on positive predictive values for different serological thresholds. Results: When assuming EPIONCHO-IBM exposure patterns, children aged <10 years are the most informative for seromonitoring; when assuming ONCHOSIM exposure patterns, 5–14 year olds are the most informative (as published elsewhere). Omitting density-dependent parasite establishment results in more lenient seroprevalence thresholds, even for higher baseline infection prevalence and shorter treatment durations. Conclusions: Selecting appropriate seromonitoring age groups depends critically on age-dependent exposure patterns. The role of density dependence on elimination thresholds largely explains differing EPIONCHO-IBM and ONCHOSIM elimination predictions.