deletions | additions       diff --git a/section_Historical_background_Incidence_surveys__.tex b/section_Historical_background_Incidence_surveys__.tex  index f9feae7..b5de2e2 100644  --- a/section_Historical_background_Incidence_surveys__.tex  +++ b/section_Historical_background_Incidence_surveys__.tex 
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Global reassessment\cite{10517722}.  Using tuberculin survey results\cite{Styblo1985}  $$I^+ = \frac{\lambda 10^5}{2 \times 10} = 50.10^{-5} y^{-1}$$