Figure 1. Seasonal incidence of Mycobacterium avium infection in Swedish children (1983–2003) in our study (bars = real numbers) and as predicted by nonlinear regression sine functions (equations: y = a + bsin[(x – c)Π/6], where x represents the months (1–12) (www.smhi.se), and with “a,” “b,” and “c” characteristic for each curve and b ≠ 0 with statistical significance, p<0.05, for all these curves. (See also online Appendix Table, available from www.cdc.gov/EID/content/14/4/661-appT.htm) A) All children. The curves were statistically significant, p<0.05, for both 1983–1997 and 1998–2003, and so the data for all years were grouped together. UCL, upper confidence limit; LCL, lower confidence limit. B) Children <2 years and >2 years of age, respectively. “b,” amplitude of curve, has a tendency to be greater for children <2 years of age (p = 0.07) and “c” is slightly smaller for children >2 years of age, representing a shift to the right of the curve, though not statistically significant. Pred, predicted.