Quantifying the role of contact sampling for poliovirus detection in Nigeria

Figures

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  Fig 1. Spatial and temporal distribution of AFP and contact sampling in Nigeria between 2017 and 2023. a. Spatial distribution of AFP cases, b. the contacts and c. the number of nOPV2 supplementary immunisation activities (SIAs), d. Temporal distribution of the number of AFP cases stratified by the number of contacts sampled per case, e. Spatial and f. Temporal distribution of the false negative AFP (FN AFP: those whose stool tested negative for VDPV2 but whose contact(s)’ stool was VDPV2-positive. Basemap layer: WHO GIS Centre for Health (https://gis-who.hub.arcgis.com/pages/b84fca387fa74cc895b6eff65470bac3).

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  Fig 2. Relative contribution and effects of the factors included in the Boosted Regression Tree ensemble model assessing the probability of a VDPV2 positive contact when the index AFP case is VDPV2 positive themselves. a. relative contribution of the factors scaled to 100% (nb = number, TP = true positive); b. marginal effects of the delay in days between AFP onset and contacts’ stools sampling; c. marginal effects of the age of the AFP case; d. number of true positive AFP cases in the last month. The marginal effects of the other factors are presented in S3 Fig.

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  Fig 3. Relative contribution and effects of the factors included in the Boosted Regression Tree ensemble model of the probability of a false negative AFP case in Nigeria. a. relative contribution of the factors scaled to 100% (nb = number, TP = true positive); b. marginal effects of the age of the AFP; c. marginal effects of the number of true positive AFP cases in the last month; d. marginal effects of the delay in days between AFP onset and AFP stools sampling for several values of the delay between the collection of stools from the AFP and those of the contacts. The marginal effects of the other factors are presented in S6 Fig.

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  Fig 4. Importance of the timeliness of stool collection in the probabilities of a VDPV2 positive contact and a false negative AFP case in Nigeria. a. distribution of the days between the onset of the AFP and the collection of stools for the AFP cases in pink and the contacts in blue regardless of their infection results; b. distribution of the days between the onset of the AFP and the collection of stools for the VDPV2 AFP cases in pink, the VDPV2 contacts in blue and the false negative AFP in gold; c. probability of VDPV2 contact in blue and false negative AFP in gold depending on the days between the onset of AFP and the collection of the corresponding stools. (FN = false negative).