Fig 2. Distribution of seronegative and seropositive populations per antigen.

For each antigen, the log₁₀-transformed OD data from the two communities over the two seasons were combined and fitted to a mixture model. The mean log₁₀-OD of the Gaussian corresponding to the seronegative population plus log₁₀-three standard deviations was calculated, back-transformed and used as the cut-off for antigen-specific antibody seropositivity based on the distribution. Blue vertical lines in each case represent the estimated positivity cut-off values.