Table 2.

Parameter Definitions Used in an Analysis of the Symptomatic Proportion of Zika Virus Infections in Multiple Countries, 2018

Parameter	Description	Notation
$P_Z$	Probability of ZIKV infection	$P[Z^{+}]$
$P_{SZ}$	Probability of having symptoms caused by ZIKV	$P[C|Z^{+}]$
$P_{SB}$	Baseline probability of symptoms	$P\left[C\prime |Z^{-}\right]=P\left[C\prime |Z^{+}\right]$a
$sen$	Sensitivity of the test	$P\left[T^{+}|Z^{+}\right]$
$spe$	Specificity of the test	$P[T^{-}|Z^{-}]$
$\mathrm{\gamma }$	Indicator for inclusion of outcome C ∩ C′	$\{\begin{array}{cc}0& \mathrm{do}\mathrm{not}\mathrm{include}C\cap C\prime \\ 1& \mathrm{include}C\cap C\prime \end{array}$

Abbreviations: C, symptoms caused by ZIKV; C′, symptoms not caused by ZIKV; T⁺, positive diagnostic test result; T⁻, negative diagnostic test result; ZIKV, Zika virus; Z⁺, infected with Zika virus; Z⁻, not infected with Zika virus.

^a We assumed that the rate of symptoms not caused by ZIKV is the same for ZIKV-infected and not-ZIKV-infected persons.