Temporal stability of five immunologic assays at various time intervals. X axis: The first group of columns represents assays performed at four different 3-week intervals (Aug. 24 to Sept. 15, Sept. 15 to Oct 6, Apr. 6 to May 5, May 5 to May24). The second group of columns represents assays performed at two different 6-week intervals (Aug. 24 to Oct. 6, Apr. 6 to May 24). The single columns at far right represent assays performed at a single 6-month (Oct. 6 to Apr. 6) and 9-month interval (Aug. 24 to May 24). Horizontal dotted lines across 3-week or 6-week columns indicate average kappa scores. Sample number comparison represented by each column is 16 unless otherwise specified. Y axis: Kappa score: Scores of 0.81–1.0, 0.61–0.80, 0.41–0.60, 0.21–40, and <0.20 indicate, respectively, almost perfect agreement and high stability, substantial stability, moderate stability, fair stability, and slight to no stability. A: 3D7 MSP-1₄₂ stimulated INF-γ production measured by ELISPOT. Kappa scores indicate moderate temporal stability over 3-week intervals (0.41) with fair stability (0.22) at 6-week intervals. Sample number for each column from left to right is 15, 10, 11, 12, 14, 16, and 16. B: 3D7 MSP-1₄₂ IgG measured by ELISA. Kappa scores indicate high (0.86) and substantial temporal stability (0.72) over 3-week and 6-week intervals. At 6-month and 9-month intervals, stability was fair and moderate. C: FVO MSP-1₄₂ IgG measured by ELISA. Kappa scores indicate high to substantial temporal stability for all time intervals tested. The average kappa score for 3-week and 6-week intervals is 0.91 and 0.82. D: MSP-1₁₉ IIA. Kappa score at 3-week interval (0.31) indicates fair temporal stability that disappears at longer time intervals. E. Growth Inhibitory Assay (GIA). Kappa scores at 3-week (0.37), 6-week (0.51), and 6-month interval indicate fair to moderate stability. The kappa score at the 9-month interval (0.20) indicated the lowest degree of temporal stability.

Kisumu rainfall (mm/month) from July 2004 to July 2005. The left Y axis indicates mm of monthly rainfall (solid squares) and the right Y axis depicts percent inhibition due to MSP-1₁₉ IIA (open triangles). Rainfall is displayed at monthly time points. Peaks in rainfall were observed in September (corresponding to the short rains in western Kenya) and in May (corresponding to the long rains). MSP-1₁₉ IIA was measured at approximately 3-week intervals at time points indicated. Higher levels of MSP-1₁₉ IIA were observed with increased rainfall.

Temporal stability of quantitative measurements of antibodies. A: MSP-1₄₂ IgG levels (Mean ± SEM) measured by ELISA (solid circles, FVO; solid triangles, 3D7) at the 6 time points. Each time point is separated by approximately 3 weeks with the exception of October 6 to April 6 time points which are separated by 6 months (denoted by two short parallel lines through the x-axis). No significant change in IgG levels was observed over time. B: GIA (open squares) and MSP-1₁₉ IIA (open triangles) (Mean ± SEM) at the 6 time points. Between October 6 and April 6 time points, a statistically significant increase in MSP-1₁₉ IIA (p = .02, paired t test) was observed. No significant change in GIA levels was observed over of any of the other time points.