Figure 1.

Factors affecting the prevalence of all 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 in age-prevalence profile. The overall likelihood ratio for the goodness of fit of the model together with the REGION*SEX* PRESENCE/ABSENCE of infection term cited in the text and two additional terms not incorporating presence/absence of infection was χ²₁₄₂₈ = 1335, P = 0.96). For the assessment of the significance of individual terms see the text.