### Simple Estimates for Local Prevalence of Latent Tuberculosis Infection, United States, 2011–2015

Maryam B. Haddad , Kala M. Raz, Timothy L. Lash, Andrew N. Hill, J. Steve Kammerer, Carla A. Winston, Kenneth G. Castro, Neel R. Gandhi, and Thomas R. Navin
Author affiliations: Centers for Disease Control and Prevention, Atlanta, Georgia, USA (M.B. Haddad, K.M. Raz, A.N. Hill, J.S. Kammerer, C.A. Winston, T.R. Navin); Emory University, Atlanta (M.B. Haddad, T.L. Lash, A.N. Hill, C.A. Winston, K.G. Castro, N.R. Gandhi)

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#### Table 1

Formula and examples of method for estimating prevalence of latent TB infection, United States, 2011–2015*

Variable
a
b
c
d
e
f
g
h
Jurisdiction Population Average annual no. active TB cases Proportion of TB cases attributed to recent transmission Annual no.  cases attributed to reactivation TB Estimated no. infected residents if 0.10% annual risk for progression Estimated prevalence of infection if 0.10% annual risk for progression, % Sensitivity analysis for  estimated prevalence of latent infection, %
Lower uncertainty limit based on 0.14% annual risk for progression Upper uncertainty limit based on 0.06% annual  risk for progression
Example X Any size 0 NA 0 NA <1 NA NA
Example Y 150,000 1 0 1 1,000 0.7 0.5 1.1
Example Z 2,000,000 50 0.2 40 40,000 2.0 1.4 3.3

*Let a = jurisdiction population, b = average annual no. TB cases in that jurisdiction, and c = proportion of TB cases attributed to recent transmission (i.e., [1 – c] = proportion attributed to latent TB infection). Then if b = 0, d = 0, and f <1%, otherwise d = b × (1 – c) and e = d/0.0010 if one assumes a 0.10% annual risk and f = e/a (×100 to express as a percentage) or (d/0.0014/a for lower uncertainty limit and h = d/0.0006/a for upper uncertainty limit. NA, not applicable; TB, tuberculosis.

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Page created: September 16, 2018
Page updated: September 16, 2018
Page reviewed: September 16, 2018
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