Fig 1.
Proportion of participants testing positive for antigen (Ag) and individual antibodies (Abs) if the participants tested negative for (i) Ag, (ii) Bm14 Ab, (iii) Wb123 Ab, or (iv) Bm33 Ab, adjusted for survey design and standardised by age and sex, Samoa 2018.
Fig 2.
Proportion of participants testing positive for combinations of antigen (Ag) and antibodies (Abs) if the participants tested negative for (i) Bm14 Ab and Ag, (ii) Wb123 Ab and Ag, (iii) Bm14 Ab and Wb123 Ab, (iv) Bm33 Ab and Ag, (v) Bm14 Ab and Bm33 Ab, or (vi) Bm33 Ab and Wb123 Ab, adjusted for survey design and standardised by and sex, Samoa 2018.
Table 1.
Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and area under the receiver-operating characteristic curve (ROC) of individual antibodies (Abs), and combinations of Abs to classify participants as antigen-positive, Samoa 2018.
Fig 3.
Sensitivity, specificity, and area under the receiver-operating characteristic curve (ROC) of individual antibodies (Abs), and combinations of Abs, to classify participants as antigen-positive, Samoa 2018.
ROC = area under the receiver-operating characteristic curve.
Fig 4.
Adjusted relative risk ratio (RRR) for testing positive to antigen (Ag), antibody (Ab), and a combination of markers, by age and primary sampling unit (PSU) selection, compared with children aged 5-9 years as a reference, Samoa 2018.
Red line indicates an RRR of 1.0. Values above 1.0 indicate an increased risk of seropositivity for the Ag, Ab, or combination of Ag and Ab listed on the y-axis. Values below 1.0 indicate a reduced risk of seropositivity.
Fig 5.
Ratio of antibody (Ab) to antigen (Ag)-positives for Bm33, Wb123 and Bm14 Abs by age, sex, and primary sampling unit (PSU) selection, adjusted for survey design, Samoa 2018.
Dashed red line indicates a ratio of 1.0.
Table 2.
Number need to test for different sampling strategies and age groups using antigen (Ag), Bm14 antibody (Ab), Wb123 Ab, and Bm33 Ab, Samoa 2018. (A) Average number needed to test to identify one positive person (NNTestav), (B) Number needed to test to provide a 50% chance of identifying at least one positive person (NNTest50), and (C) Number needed to test to provide a 95% chance of identifying at least one positive person (NNTest95).
Fig 6.
Probability of detecting at least one positive case of antigen (Ag), Bm14 antibody (Ab), Wb123 Ab, or Bm33 Ab for (A) 5-9 years old in randomly and purposively selected primary sampling units (PSUs) and (B)
≥10 years old in randomly and purposively selected PSUs (assumes that positive cases are independent events).