Immigrants and the Spread of Tuberculosis in the United States: A Hidden Cost of Immigration by, Michael J. Greenwood and Watson R. Warriner

Research Question and Motivation Do immigrants from countries with high TB incidence affect Tuberculosis cases among the foreign-born population, and in turn, is the native-born population in the United States infected? TB is the second largest killer from infectious diseases in the world TB Prevalence is on the rise around the world TB rates in the U.S. continue to decline, but by less each year Does something have to give? Is there transmission between cohorts?

Figure 1. TB Incidence Map (2006)

Figure 2. HIV Prevalence Map (2007)

Notes: Data obtained from the CDC Wonder OTIS Database and U.S. Census Bureau

Notes: Data obtained from World Health Organization Tuberculosis Programme

Notes: Data obtained from the CDC Wonder OTIS Database and U.S. Census Bureau

TB Background Types – Latent or Active Treatments – Chemotherapy (four different drugs for 6 months) – BCG (Bacillus Calmette-Guerin) Vaccine – not effective for active or re-activations Immigration Laws – Persons with TB not allowed into the U.S. – Prior to 2007: chest x-ray (only detects active) – 2007 to Present: skin test for children under 15 (detects both active and latent forms)

Related Research Little research regarding immigrant to native transmission – Stagnation in TB elimination relatively recent – Immigration has not been a primary focus in TB elimination efforts Small-scale case studies vs. larger-scale epidemiological studies Conclusions – Positively correlated with TB: Number of minorities, population density, immigration, poverty, and HIV/AIDS – Findings are inconsistent – No research on transmission to native-born populations

Theoretical Background Top 50 Metropolitan Statistical Areas (MSAs) by total TB cases ( ) – Limitation due to suppression of TB statistics – Account for 69.5% of total TB cases in the U.S. ( ) Observation = an MSA in a given year – 750 total (15 years x 50 MSAs)

Theoretical Background Recursive Model (A -> B, B -> C) – A: High-Incidence Immigration – B: Foreign-Born TB – C: Native-Born TB 1. FBTB it = f (HMIG it, LMIG it, DEM it, SOCECON it ) 2. NBTB it = g (FBTB it, DEM it, SOCECON it )

Data 1.Tuberculosis Statistics 1.Constant geographies: 2007 MSA definitions 2.Demographic and socio-economic data 3.Country-specific TB incidence data 4.MSA immigration statistics 5.HIV incidence data

Table 3. Descriptive Statistics, All Variables from Pooled Data VariableObs.MeanStd. Dev.MinMax Number of Native TB Cases (Flow) ,164 Number of Foreign-Born TB Cases (Flow) ,673 Total Immigrants (Flow)75014,27927, ,427 Immigrants from Top 50 High TB Countries (Flow)7502,6044, ,403 Total Population7502,905,6943,086,156439,32018,815,988 Native Born Population7502,417,6002,278,708322,55613,487,097 Foreign-Born Population750488,094891,79413,3355,328,891 Males*7501,422,8011,497,485212,2439,103,790 Females*7501,482,8941,589,332227,0779,712,198 Youth (Under 22 Years Old)*750901,056938,848181,9165,441,926 Middle Age (Between 21 and 60 Years Old)*7501,558,6581,662,414193,37910,027,211 Seniors (Above 59 Years Old)*750445,981499,92357,2853,346,851 Whites7501,740,1281,629,98755,68410,251,089 Blacks750409,482538,4301,0973,145,815 Asians750169,176299,3981,5441,755,257 American Indians75010,49911, ,438 Other Races75057,93170, ,688 Hispanics750518,479893,0028,1615,675,443 Population Density (people per square mile) ,798 Families earning under $25,000 per year (2007 $)750103,040106,68714,603670,217 HIV Incidence (per 100,000) for * Not in Regressions

Econometric Approach Five Estimations per Regression – FOCUS: Temporal and Divisional (9 Census Divisions) Fixed Effects Base Year = 1993, Base Division = Pacific Immigration Variable is Summed, t and t-1 HIV/AIDS Incidence Inclusion – 2006, 12% TB cases in U.S. were also co-infections with HIV – Data Limited to 2003 – 2007 (Panel Data with 250 Observations) – Only an estimated effect

Econometric Approach Double-log regression – Results can be interpreted as elasticities Or…the percentage change in the dependant variable that results from a one-percent change in the independent variable 1.FBTB it = α 1 (HMIG it β 1 ) (LMIG it β 2 ) (FBPop it β 3 ) (NBPop it β 4 ) (PopDen it β 5 ) (Poverty it β 6 )( ε it ) 2. NBTB it = α 2 (FBTB it ρ 1 ) (NBPop it ρ 2 ) (FBPop it ρ 3 ) (White it ρ 4 ) (Black it ρ 5 ) (Asian it ρ 6 ) (AmerInd it ρ 7 ) (OtherRace it ρ 8 ) (Hispanic it ρ 9 ) (PopDen it ρ 10 ) (Poverty it ρ 11 ) ( ε it )

Table 4. Number of TB Cases among the Foreign-Born Population in U.S. Metropolitan Areas, : Double Logarithmic Estimates (β) and t-Ratios (t) (1)(2)(3)(4)(5) VARIABLESln(FBTB) ln(Immigrants from Top 50 Inc. Countries) β:0.174***0.259***0.242***0.270***0.287*** t:(5.825)(7.798)(3.410)(7.893)(7.980) ln(Immigrants from All Other Countries)0.136***0.177*** *** (2.881)(3.328)(0.764)(2.595)(0.581) ln(Foreign-Born Population)0.818***0.731***1.498***0.739***0.841*** (16.40)(12.63)(6.748)(12.33)(12.71) ln(Native Population)-0.122*-0.268***3.378***-0.323***-0.234*** (-1.892)(-3.809)(3.005)(-4.624)(-3.597) ln(Population Density)0.0404* *** *** (1.757)(1.361)(-3.595)(1.188)(3.337) ln(Families in Poverty)-0.229***-0.116* ** (-3.698)(-1.744)(1.015)(-0.753)(-2.178) Temporal Fixed EffectsNYYYY Cross-Sectional Fixed EffectsNNYNN Regional Fixed EffectsNNNYN Divisional Fixed EffectsNNNNY Observations750 R-squared Robust t-statistics in parentheses *** p<0.01, ** p<0.05, * p<0.1

Table 5. Number of TB Cases among the Native-Born Population in U.S. Metropolitan Areas, : Double Logarithmic Estimates (ρ) and t-Ratios (t) (1)(2)(3)(4)(5) VARIABLESln(NBTB) ln(Foreign-Born TB Cases) ρ:0.279***0.136***0.198***0.129***0.111*** t:(5.086)(3.296)(5.599)(3.334)(2.685) ln(Native Population) ** (1.016)(0.819)(1.152)(-1.989)(-0.272) ln(Foreign-Born Population)-0.407***-0.305***0.663**-0.349***-0.241** (-4.407)(-4.355)(2.205)(-4.800)(-2.575) ln(Non-Hispanic Whites)-0.263**-0.369*** (-2.409)(-4.730)(0.768)(-0.177)(-1.218) ln(Non-Hispanic Blacks)0.369***0.416***0.548**0.232***0.234*** (14.12)(20.28)(2.395)(9.321)(7.179) ln(Asians)0.271***0.123***-0.923***0.299***0.179*** (5.202)(3.035)(-4.195)(5.962)(3.037) ln(American Indians)0.149*** *** * (4.359)(-1.145)(0.122)(-5.287)(-1.782) ln(Other Races, Including Multi-Racial)-0.549*** * (-10.90)(-1.828)(0.904)(-0.245)( ) ln(Hispanics)0.104**0.182***-0.497**0.129***0.134*** (2.279)(5.142)(-2.375)(3.582)(3.411) ln(Population Density)0.191***0.106*** ** (4.315)(2.969)(-1.284)(1.563)(2.096) ln(Families in Poverty)0.674***0.690***0.759*1.017***0.758*** (7.138)(8.513)(1.939)(11.03)(7.237) Temporal Fixed EffectsNYYYY Cross-Sectional Fixed EffectsNNYNN Regional Fixed EffectsNNNYN Divisional Fixed EffectsNNNNY Observations750 R-squared Robust t-statistics in parentheses *** p<0.01, ** p<0.05, * p<0.1

Table 6. Number of TB Cases among the Foreign-Born Population in U.S. Metropolitan Areas (HIV Incidence Included), : Double Logarithmic Estimates (β) and t-Ratios (t) (5)(6) VARIABLESln(FBTB) ln(Imms. Of Top-50 Inc. Countries) β:0.297***0.309*** t:(4.977)(5.170) ln(Imms. Of All Other Countries) (-0.858)(-0.919) ln(Foreign-Born Population)0.911***0.913*** (7.995)(7.944) ln(Native Population)-0.238**-0.250** (-1.972)(-2.106) ln(Population Density)0.112***0.113*** (2.615)(2.611) ln(Families in Poverty) (-1.018)(-0.803) ln(HIV Incidence Rate) (-1.430) Temporal Fixed EffectsYY Cross-Sectional Fixed EffectsNN Regional Fixed EffectsNN Divisional Fixed EffectsYY Observations250 R-squared Robust t-statistics in parentheses *** p<0.01, ** p<0.05, * p<0.1 Table 7. Number of TB Cases among the Native-Born Population in U.S. Metropolitan Areas (HIV Incidence Included), : Double Logarithmic Estimates (ρ) and t-Ratios (t) (5)(6) VARIABLESln(NBTB) ln(Foreign-Born TB Cases) ρ:0.172***0.136** t:(2.603)(2.102) ln(Native Population) (0.309)(1.010) ln(Foreign-Born Population)-0.366**-0.502*** (-2.326)(-3.550) ln(Non-Hispanic Whites) (-1.182)(-1.317) ln(Non-Hispanic Blacks)0.240*** (4.312)(1.388) ln(Asians)0.265**0.368*** (2.570)(3.556) ln(American Indians) (-0.318)(0.824) ln(Other Races, Incl. Multi-Racial) * (-1.215)(-1.775) ln(Hispanics)0.137*0.170*** (1.945)(2.754) ln(Population Density)0.140**0.137** (2.315)(2.346) ln(Families in Poverty)0.651***0.660*** (4.147)(4.001) ln(HIV Incidence Rate) 0.325*** (4.198) Temporal Fixed EffectsYY Cross-Sectional Fixed EffectsNN Regional Fixed EffectsNN Divisional Fixed EffectsYY Observations250 R-squared Robust t-statistics in parentheses *** p<0.01, ** p<0.05, * p<0.1

Empirical Results Positive and significant elasticities for key independent variables in both regressions Increased immigration from high-TB incidence countries -> increased number of TB cases among the foreign-born -> more native-born TB cases Transmission exists from the foreign to the native- born populations in the sample

Societal Cost of TB in U.S. for 2008 Societal Cost Makeup $1.47 billion - $2.63 billion (not including transmission) –0.018% of total GDP ($14.61 trillion) TST for all Legal Permanent Resident Immigrants = $23.8 million –Between 0.90% and 1.62% of total TB cost Minor relative cost to eliminate incoming TB

Discussion Advantages Broad sample and isolation of urban areas Limitations Linear interpolation of demographic data Demographic data only gathered for entire population Immigration data only include Legal Permanent Residents Extensions Two way transmission – two staged least squares Obtain more years for HIV incidence data

Implications of Research Incoming latent TB among Immigrants infecting the natives through transmission via the foreign-born population TST for all immigrants highly recommended HIV Travel Ban Lifted in 2009 – Major Implications to this study – 1/3 of those infected with HIV are TB co-infections