Figure 3.

Factors affecting the prevalence of all protozoan parasites combined. (A) Changes in prevalence during the 7 years of the study. (B) Differences between the age-prevalence profile between the years of the study. (C) Differences in the age-prevalence profile by region of origin of subjects. (D) Difference between the sexes among subjects from the five regions. The overall likelihood ratio for the goodness of fit of the model based on the three terms summarized in B, C, and D and two additional terms not incorporating presence/absence of infection was χ²₁₄₄₀ = 1365.7, P = 0.92). For the assessment of the significance of individual terms see the text.