Date of Award
Master of Public Health (MPH)
BACKGROUND: On World TB Day 2016, CDC reported an increase in number of US tuberculosis (TB) cases in 2015, the first time in 23 years. TB is the largest cause of mortality from any bacterial disease worldwide, with 95% of cases and deaths in low and middle-income countries, where it remains endemic. The recent increase in US TB cases highlights the fact that TB is a global issue, thus requiring a global effort to achieve elimination, with particular focus on active TB and Latent TB Infection (LTBI) identification and treatment among populations at high risk. The refugee population requires particular attention, considering TB disproportionately afflicts refugees and there are more refugees worldwide today than in the past 20 years. Georgia is among the top 10 US states for refugee arrivals, with majority resettling in DeKalb County, approximately 90% in 2010. There is a lack of data on TB rates among these populations and effects of implementation of the 2007 expanded CDC Technical Instructions on imported TB and LTBI reactivation.
OBJECTIVES: (1) Estimate and compare TB disease incidence rates among refugee, other foreign-born, and US-born populations in DeKalb County from 2004 to 2015 (2) Determine refugee TB case contribution to total DeKalb County TB case burden (3) Examine possible trends in number of cases diagnosed ≤ 6 months of US entry, among refugee and other foreign-born persons screened overseas before and after implementation of 2007 expanded CDC Technical Instructions.
METHODS: Retrospective study on all new TB cases diagnosed in DeKalb County during 2004-2015. Due to the lack of data on refugee population estimates along with the dynamic nature of this population, three different annual incidence rates were calculated for refugees and other FB. Participant characteristics were compared using chi-square tests and univariate analyses to identify significant differences between groups. Logistic regression was used to model change in number of TB diagnoses ≤ 6 months of US entry against implementation status (pre vs. post) and immigration status (refugee vs. other-FB).
RESULTS: From 2004 to 2015, a total of 898 active TB cases were diagnosed in DeKalb County; 569 total foreign-born (144 refugees and 425 other foreign-born) and 329 US-born. Age, race/ethnicity, TB verification type, HIV status, and previous TB diagnosis were found to have significant differences between groups (p < 0.05). Throughout the study period, the highest TB incidence rate was among refugees followed by other FB, and drastically lower rates among US-born. There were significantly more diagnoses ≤ 6 months of US entry among post vs pre-implementation, OR: 2.784 (95% CI: 1.683 – 4.606). Refugee vs. other-FB, OR: 5.103 (95% CI: 3.085 – 8.442). Majority of cases with prior B1 classification (83.6%) were diagnosed ≤ 6 of US entry, which is considered to be possible imported TB, While (90.9%) persons with Class B2, although few, were diagnosed ≤ 6 months of US entry, which suggests possible LTBI reactivation.
DISCUSSION: Although TB cases and rates have decreased in DeKalb County over the years, particularly among US-born persons, the foreign-born population remains disproportionately afflicted, with majority of county disease burden, over 70% in 2015. Refugee TB rates in DeKalb County are more comparable to rates in high TB incidence low and middle-income countries rather than US rates. Imported TB and LTBI activation may be major factors involved in the stagnation of progression towards TB elimination. Efforts need to refocus on LTBI identification and treatment to tackle the global issue of TB.
Ahmad, Maryam, "Tuberculosis (TB) Trends Among Refugee, Other Foreign-Born, and US-Born Cases in DeKalb County During 2004-2015." Thesis, Georgia State University, 2016.