Mycobacterium avium lymphadenopathy among children, Sweden

Abstract

We studied Mycobacterium avium lymphadenopathy in 183 Swedish children (<7 years of age) from 1998 through 2003. Seasonal variation in the frequency of the disease, with a peak in October and a low point in April, suggests cyclic environmental factors. We also found a higher incidence of the disease in children who live close to water.

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 (–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.

Figure 2

Number of cases, incidence rates (cases/100,000 children/year), and 95% confidence intervals of Mycobacterium avium disease in children grouped according to ecologic, geographic, and cultivation zones, Sweden, 1998–2003. Freshwater, coastal (incidence of saltwater and brackish water were similar within this group), inland, urban (Stockholm, Göteborg, and Malmö, the 3 largest cities in Sweden) areas and the different cultivation zones (1–8, zone 1 being the warmest) are depicted. When assigning zones to each case, we assumed that the children were infected in the area where they resided. UCL, upper confidence limit; LCL, lower confidence limit.