Decline in tuberculosis among Mexico-born persons in the United States, 2000-2010

Scaling of mortality in 742 metropolitan areas of the Americas

We explored how mortality scales with city population size using vital registration and population data from 742 cities in 10 Latin American countries and the United States. We found that more populated cities had lower mortality (sublinear scaling), driven by a sublinear pattern in U.S. cities, while Latin American cities had similar mortality across city sizes. Sexually transmitted infections and homicides showed higher rates in larger cities (superlinear scaling). Tuberculosis mortality behaved sublinearly in U.S. and Mexican cities and superlinearly in other Latin American cities. Other communicable, maternal, neonatal, and nutritional deaths, and deaths due to noncommunicable diseases were generally sublinear in the United States and linear or superlinear in Latin America. Our findings reveal distinct patterns across the Americas, suggesting no universal relation between city size and mortality, pointing to the importance of understanding the processes that explain heterogeneity in scaling behavior or mortality to further advance urban health policies.

Development of a Surveillance Definition for United States-Mexico Binational Cases of Tuberculosis

OBJECTIVES

Consistently collected binational surveillance data are important in advocating for resources to manage and treat binational cases of tuberculosis (TB). The objective of this study was to develop a surveillance definition for binational (United States-Mexico) cases of TB to assess the burden on US TB program resources.

METHODS

We collaborated with state and local TB program staff members in the United States to identify characteristics associated with binational cases of TB. We collected data on all cases of TB from 9 pilot sites in 5 states (Arizona, California, Colorado, New Mexico, and Texas) during January 1-June 30, 2014, that had at least 1 binational characteristic (eg, "crossed border while on TB treatment" and "received treatment in another country, coordinated by an established, US-funded, binational TB program"). A workgroup of US state, local, and federal partners reviewed results and used them to develop a practical surveillance definition.

RESULTS

The pilot sites reported 87 cases of TB with at least 1 binational characteristic during the project period. The workgroup drafted a proposed surveillance definition to include 2 binational characteristics: "crossed border while on TB treatment" (34 of 87 cases, 39%) and "received treatment in another country, coordinated by an established, US-funded, binational TB program" (26 of 87 cases, 30%). Applying the new proposed definition, 39 of 87 pilot cases of TB (45%) met the definition of binational.

CONCLUSION

Input from partners who were responsible for the care and treatment of patients who cross the United States-Mexico border was crucial in defining a binational case of TB.

Challenges and solutions to estimating tuberculosis disease incidence by country of birth in Los Angeles County

Background

Among U.S. residents, tuberculosis (TB) disease disproportionally affects non-U.S.-born persons and varies substantially by country of birth. Yet TB disease incidence rates by country of birth are not routinely reported despite these large, known health disparities. This is in part due to the technical challenges of using standard regression analysis with a communicable disease. Here, we estimate tuberculosis disease incidence rates by country of birth and demonstrate methods for overcoming these challenges using TB surveillance data from Los Angeles County which has more than 3.5 million non-U.S.-born residents.

Methods

Cross-sectional data on 5,447 cases of TB disease from Los Angeles County were combined with population estimates from the American Community Survey to calculate TB disease incidence rates for 2005 through 2011. Adjusted incidence rates were modelled using Poisson and negative binomial regressions. Bayesian models were used to account for the uncertainty in population estimates.

Results

The unadjusted incidence rate among non-U.S.-born persons was 15 per 100,000 person-years in contrast to the rate among U.S-born persons, 2 per 100,000. The unadjusted incidence rates were 44 and 12 per 100,000 person-years among persons born in the Philippines and Mexico, respectively. In adjusted analysis, persons born in the Philippines were 2.6 (95% CI: 2.3–3.1) times as likely to be reported as a TB case than persons born in Mexico. Bayesian models showed similar results.

Conclusion

This study confirms substantial disparities in TB disease by country of birth in Los Angeles County. Accounting for age, gender, years in residence and year of diagnosis, persons from the Philippines, Vietnam and several other countries had much higher rates of reported TB disease than other foreign countries. We demonstrated that incidence rates by country of birth can be estimated using available data despite technical challenges.

Mind the gap: TB trends in the USA and the UK, 2000-2011

BACKGROUND

TB remains a major public health concern, even in low-incidence countries like the USA and the UK. Over the last two decades, cases of TB reported in the USA have declined, while they have increased substantially in the UK. We examined factors associated with this divergence in TB trends between the two countries.

METHODS

We analysed all cases of TB reported to the US and UK national TB surveillance systems from 1 January 2000 through 31 December 2011. Negative binominal regression was used to assess potential demographic, clinical and risk factor variables associated with differences in observed trends.

FINDINGS

A total of 259,609 cases were reported. From 2000 to 2011, annual TB incidence rates declined from 5.8 to 3.4 cases per 100,000 in the USA, whereas in the UK, TB incidence increased from 11.4 to 14.4 cases per 100,000. The majority of cases in both the USA (56%) and the UK (64%) were among foreign-born persons. The number of foreign-born cases reported in the USA declined by 15% (7731 in 2000 to 6564 in 2011) while native-born cases fell by 54% (8442 in 2000 to 3883 in 2011). In contrast, the number of foreign-born cases reported in the UK increased by 80% (3380 in 2000 to 6088 in 2011), while the number of native-born cases remained largely unchanged (2158 in 2000 to 2137 in 2011). In an adjusted negative binomial regression model, significant differences in trend were associated with sex, age, race/ethnicity, site of disease, HIV status and previous history of TB (p<0.01). Among the foreign-born, significant differences in trend were also associated with time since UK or US entry (p<0.01).

INTERPRETATION

To achieve TB elimination in the UK, a re-evaluation of current TB control policies and practices with a focus on foreign-born are needed. In the USA, maintaining and strengthening control practices are necessary to sustain the progress made over the last 20 years.

Abrupt Decline in Tuberculosis among Foreign-Born Persons in the United States

While the number of reported tuberculosis (TB) cases in the United States has declined over the past two decades, TB morbidity among foreign-born persons has remained persistently elevated. A recent unexpected decline in reported TB cases among foreign-born persons beginning in 2007 provided an opportunity to examine contributing factors and inform future TB control strategies. We investigated the relative influence of three factors on the decline: 1) changes in the size of the foreign-born population through immigration and emigration, 2) changes in distribution of country of origin among foreign-born persons, and 3) changes in the TB case rates among foreign-born subpopulations. Using data from the U.S. National Tuberculosis Surveillance System and the American Community Survey, we examined TB case counts, TB case rates, and population estimates, stratified by years since U.S. entry and country of origin. Regression modeling was used to assess statistically significant changes in trend. Among foreign-born recent entrants (<3 years since U.S. entry), we found a 39.5% decline (-1,013 cases) beginning in 2007 (P<0.05 compared to 2000–2007) and ending in 2011 (P<0.05 compared to 2011–2014). Among recent entrants from Mexico, 80.7% of the decline was attributable to a decrease in population, while the declines among recent entrants from the Philippines, India, Vietnam, and China were almost exclusively (95.5%–100%) the result of decreases in TB case rates. Among foreign-born non-recent entrants (≥3 years since U.S. entry), we found an 8.9% decline (-443 cases) that resulted entirely (100%) from a decrease in the TB case rate. Both recent and non-recent entrants contributed to the decline in TB cases; factors contributing to the decline among recent entrants varied by country of origin. Strategies that impact both recent and non-recent entrants (e.g., investment in overseas TB control) as well as those that focus on non-recent entrants (e.g., expanded targeted testing of high-risk subgroups among non-recent entrants) will be necessary to achieve further declines in TB morbidity among foreign-born persons.