Fig 1.
The top left inset shows the location of Lihir in Papua New Guinea. The pink circle plotted at the centroid of each village illustrates passively collected data on incident yaws. The area of each circle is proportional to the total number of outpatient visits to the Lihir Medical Centre from that village during the study period and the color indicates the percentage of those visits that led to a yaws diagnosis. Note that Landolam is technically not a village but rather an informal migrant settlement. Elevation data were obtained from the Shuttle Radar Topography Mission [13]. The Papua New Guinea map was obtained from the GADM database [14].
Fig 2.
Flow diagrams for data in analysis of passively detected yaws.
(A) Exclusions of outpatient passively detected yaws cases and (B) exclusions of all outpatient visits at the Lihir Medical Centre.
Fig 3.
Spatial-temporal clusters of passively detected yaws cases.
(A) Map of results of spatial-temporal Poisson SaTScan analysis of serologically confirmed incident yaws cases, adjusted for age and sex. (B) Time series of outpatient yaws cases aggregated by month by village and for all villages combined. The y-axes for the village-specific time series range from 0 to 8. The villages are ordered to match their sequential order around the circumference of Lihir. Red, blue, and green rectangles correspond to spatial-temporal clusters 1, 2, and 3, respectively. The vertical yellow bar corresponds to when mass drug administration was implemented on Lihir.
Fig 4.
Flow diagram for data in analysis of prevalent yaws cases.
The diagram lists serologically confirmed cases, excluded cases, and number of individuals screened by active case finding survey.
Fig 5.
Spatial clusters of actively detected serologically confirmed yaws cases.
Results of spatial-only discrete Poisson SaTScan analysis for serologically confirmed prevalent yaws cases identified via active case finding for each survey 1 through 7 (A–G, respectively). Villages that are part of statistically significant spatial clusters are shaded in red and not statistically significant clusters are shaded in pink. Villages are shaded gray if they were part of the analysis in the corresponding survey (but not identified as part of a cluster). Villages are excluded from the map for each survey where the number of individuals screened in that survey in that village is unknown. The arrows point from each cluster to details describing the number of observed yaws cases in that cluster, the number of expected yaws cases, the ratio of observed to expected, and the p-value for that cluster.
Fig 6.
Passively detected yaws cases by primary school attendance area and year.
(A) Map of Lihir villages with the colors corresponding to empirically derived primary school attendance areas. Each solid black triangle marks the location of a primary school. (B–L) Yaws diagnoses among 8- to 14-year-olds as a proportion of outpatient visits for the entire study period (B) and each year 2006 to 2015 (C–L, respectively). Each data point corresponds to a village and the background colors in each plot correspond to the primary school attendance areas illustrated in (A). The data points ordered left-to-right correspond to the clockwise sequences of villages around Lihir arbitrarily starting from Londolovit, the large village in the northeast quadrant of the island. The p-values were obtained from a permutation test.