Authors

L E Coffeng¹; W A Stolk¹; S J de Vlas¹; A Golden²; T de los Santos²; G J Domingo²;  ¹ Erasmus MC University Medical Center Rotterdam, Netherlands;  ² PATH, United States

Discussion

BACKGROUND: One of the currently recommended methods to evaluate elimination of onchocerciasis is to test whether Ov16-antibody prevalence in children of age 0-9 is <0.1%. The predictive accuracy of this decision threshold should be reviewed in context of the geographical variation in pre-control epidemiology of onchocerciasis and the history of mass drug administration (MDA). METHODS: We use the ONCHOSIM model to investigate the predictive value of Ov16 antibody prevalence in various age groups for elimination of onchocerciasis in a variety of endemic settings and MDA scenarios. RESULTS: Sensitivity and specificity of Ov16 antibody prevalence for predicting elimination highly depends on the pre-control epidemiological situation, history of MDA, the age group that is sampled, and the chosen Ov16 antibody prevalence threshold. Still, threshold values can be defined such that positive predictive values for elimination are close to 100% regardless of the history of MDA. Importantly, we predict that Ov16 antibody prevalence in school-aged children (age 5-14) provides the most information about prospects of elimination. DISCUSSION: The findings from this study suggest that 1) broadening the sampled population to school-age children instead of children under ten increases the accuracy of anti-Ov16 prevalence as a predictor for elimination; 2) the current threshold of 0.1% may be too stringent except for the most highly endemic settings; and 3) a tiered approach to defining thresholds based on pre-control endemicity is pertinent.