Reported Tuberculosis in the United States, 2019

Origin of Birth

Origin of birth is the most prominent risk factor for TB in the United States. CDC uses U.S. Census Bureau definitions for national origin, where persons are U.S.-born if they were entitled to U.S. citizenship at birth, i.e., they were born in the United States or a U.S. territory or elsewhere to at least one U.S. citizen parent (with certain minor exceptions). All other persons are categorized as non-U.S.–born. Between 1993 and 2019, cases of TB have declined by 85.4% (to 2,541 cases) among U.S.-born persons and by 14.0% (to 6,364 cases) among non-U.S.–born persons (Table 5). Incidence rates have declined by 87.7% and 58.2% among U.S.-born and non-U.S.–born persons, respectively. Consistent with previous years, the majority of reported TB cases occurred among non-U.S.–born persons (71.4%) (Table 5). This reflects the substantially greater risk of exposure to TB outside of the United States.

The most common countries of birth among non-U.S.–born persons with TB continue to include Mexico (18.6%), the Philippines (12.5%), India (9.1%), Vietnam (7.9%), and China (6.1%) (Table 6A). These countries of birth also represent substantial proportions of the non-U.S.–born population living in the United States.⁴ In 2018, the most recent year for which data are available, 25.8% of  non-U.S.–born persons in the United States were born in Mexico, 6.0% in India, 5.1% in China, 4.8% in Philippines, and 3.1% in Vietnam. Calculation of incidence rates accounts for the size of the underlying population; however, groups with relatively small populations in the United States can have high incidence rates despite constituting a relatively small proportion of the total number of TB cases reported. Birth countries with the highest U.S. incidence rates were the Republic of the Marshall Islands (168.8 cases per 100,000 persons), the Republic of the Congo (143.8 cases per 100,000 persons), Somalia (87.3 cases per 100,000 persons), and Myanmar (81.2 cases per 100,000 persons) (Table 6B).

Among non-U.S.–born persons with TB, 13.5% of cases occurred within one year of arrival in the United States, 16.7% had been the United States 1–4 years, 11.0% for 5–9 years, 17.3% for 10–19, 29.9% for ≥20 years, and 11.7% for an unknown amount of time (Table 19).

Race/Ethnicity

Non-Hispanic Asian persons continued to represent the largest proportion of persons with TB (35.3%), followed by Hispanic persons (30.2%), non-Hispanic Black persons (19.7%), and non-Hispanic White persons (11.4) (Table 2). Incidence rates remained highest, but declined from 2018, for non-Hispanic Native Hawaiian/other Pacific Islander persons (17.6 in 2019 compared with 19.4 cases in 2018 per 100,000 persons) and non-Hispanic Asian persons (16.7 in 2019 compared with 17.3 cases in 2018 per 100,000 persons) (Table 2). Incidence rates among non-Hispanic American Indian/Alaska Native persons also declined in 2019 compared with 2018 (3.4 compared with 4.3 cases per 100,000 persons). Incidence rates remained similar in 2019 compared with 2018 rates for Hispanic persons (4.5 cases per 100,000 persons) and non-Hispanic Black persons (4.3 cases per 100,000 persons), people of more than one race/ethnicity (0.9 cases per 100,000 persons), and non-Hispanic White persons (0.5 cases per 100,000 persons) (Table 2).

The distribution of persons with TB by race/ethnicity continued to differ markedly by origin of birth (Table 3). Among US-born persons with TB, the largest racial/ethnic group was non-Hispanic Black persons (35.9%), followed by non-Hispanic White persons (29.9%), Hispanic persons (24.2%), and non-Hispanic Asian persons (4.6%) (Table 3). Approximately half of TB cases reported among non-US–born persons occurred among non-Hispanic Asian persons (47.6%), followed by Hispanic persons (32.6%), non-Hispanic Black persons (13.2%), and non-Hispanic White persons (4.0%) (Table 3). The decline in TB cases since 2003 has been lower among US-born Hispanic persons (38.4%) and non-US–born Hispanic persons (32.8%) compared with U.S.-born (68.0%) and non-U.S.–born (39.5%) non-Hispanic White persons. TB cases have declined since 2003 among U.S.-born non-Hispanic Black persons (70.5%) more than among non-U.S.–born non-Hispanic Black persons (21.1%), which may be attributable, in part, to progress in preventing TB transmission in the United States (Table 3).

Age

Distribution of persons with TB by age group in 2019 is consistent with past years, with adults age 25–64 years representing 59.2% of persons with TB (Table 4). Children and young adults aged <25 years account for 13.6%, and adults ≥65 years account for 27.2% of U.S. TB cases (Table 4). Among persons ≥15 years, incidence rates increase with increasing age group: 2.0 cases per 100,000 persons age 15–24 years, 3.0 cases per 100,000 persons age 25–44 years, 3.2 cases per 100,000 persons age 45–64 years, and 4.5 cases per 100,000 persons age ≥65 years. However, the age group with the lowest incidence rate was 5–14 (0.4 cases per 100,000 persons), followed by the youngest group, 0–4 years (1.1 cases per 100,000 persons) (Table 4). Higher TB risk in adults of older ages might be attributable to cohorts with increased risk for TB exposure and infection, compared with the present, moving through time into older age groups or to increased risk of progression to TB disease with age-related declines in immune function. Among non-U.S.–born persons, 31.6% occur among persons age 25–44, compared with 23.7% among U.S.-born persons, which might be attributable to the age distribution of non-U.S.–born persons in the United States (Table 21 and Table 22).

Primary Reason for Tuberculosis Evaluation

The majority of U.S. TB cases in 2019 were primarily evaluated for TB because of experiencing TB symptoms (55.8%), followed by abnormal chest radiograph (20.3%), and incidental lab results (10.8%). Active case-finding methods were reported as the primary reason for TB evaluation for 11.5% of TB cases, including those evaluated during targeted testing of groups expected to have elevated prevalence of TB infection (4.7%), investigation of close contacts to an infectious TB case (4.1%), immigrant medical exam (2.0%), administratively required testing for employment (other than health care workers), school admission, or other similar purposes (0.5%), or testing for health care workers (0.2%) (Table 36).

Case Verification Criteria

Since 1993, the percentage of U.S. TB cases verified through positive culture has ranged from 75.8% to 80.9%; in 2019, 79.5% of cases were verified through positive culture. Since nucleic acid amplification test results were first collected in 2008, TB cases verified solely based on this laboratory method (cases that were initially verified using nucleic acid amplification testing but subsequently confirmed via positive culture are reported as verified by culture) continue to account for a small percentage of TB cases in 2019 (2.3%). TB cases can also be verified in the absence of laboratory confirmation by meeting clinical verification criteria (Appendix B). Additionally, CDC will accept and count TB cases based on a health care provider’s diagnosis (provider diagnosis), even if the case does not otherwise meet the national surveillance case definition for TB. In 2019, 13.2% of cases were verified based on clinical criteria and 4.7% based on provider diagnosis (Table 7).

Site of Disease

TB most commonly affects the lungs but can cause disease in any part of the body. Similar to previous years, 79.4% of U.S. TB cases had pulmonary involvement (Table 7). Among the 20.6% of U.S. TB cases with only extrapulmonary involvement, the most common sites affected were the lymphatic system (34.9%), pleura (18.3%), and bones and joints (8.4%) (Table 15). TB meningitis, a particularly serious form of the disease, accounted for 4.4% of extrapulmonary cases (Table 15).

Characteristics Associated with Infectiousness

Cavitation evident on chest radiography and a positive acid-fast bacillus (AFB) sputum smear result are clinical characteristics associated with infectiousness because they indicate that large amounts of tubercle bacilli suspended in droplet nuclei might be expelled into the air when a person with TB coughs.^5,6 Other people nearby might become infected if they breathe in these particles. During 2017–2019, of the 18,363 cases with an AFB sputum smear result, 9,801 (53.4%) were smear positive. In that same period, of the 1,951 persons with pulmonary TB and an abnormal chest radiograph result reported, 219 (11.2%) had evidence of cavitary disease (Table 24).

Initial Drug Regimen

Effective TB treatment includes providing multiple anti-TB drugs over a sufficient period of time to cure the patient, prevent development of drug resistance, and minimize the risk of transmission to others. The most common regimen for drug-susceptible TB, and in situations where drug-susceptibility is unknown, includes isoniazid, I; rifampin, R; pyrazinamide, Z; and ethambutol, E (IRZE).⁷ Among persons alive at diagnosis with initial drug regimen information available in 2019, 82.5% began treatment with IRZE. An additional 11.5% began treatment with a four-drug regimen other than IRZE, 0.7% received no initial drug therapy, and 0.1% were started on one drug (Table 10).

Drug Resistance

Resistance to anti-TB drugs is a serious problem both in the United States and globally, and inadequate treatment (inadequate dosing, incomplete treatment, and nonadherence to therapy) can contribute to development of drug resistance. Resistance to isoniazid, one of the most common anti-TB drugs, can be a precursor to multidrug-resistant (MDR; defined as resistance to at least isoniazid and rifampin) TB. During 2019, 631 isoniazid-resistant TB cases were reported in the United States, a decrease from 637 cases in 2018. Of those, 90 cases had MDR TB, compared with 103 MDR TB cases in 2018. Among non-U.S.–born persons, 10.5% had TB resistant to isoniazid and 1.6% had MDR TB at initial diagnosis; among U.S.-born persons, 6.6% had TB resistant to isoniazid and 0.7% had MDR TB at initial diagnosis (Table 8 & Table 9). Extensively drug resistant TB (defined as resistance to isoniazid and rifampin, plus any fluoroquinolone and at least one injectable second-line drug) continues to be rare in the United States, with only 4 cases reported in 2019.

Directly Observed Therapy

Directly observed therapy (DOT) involves direct observation of a patient ingesting anti-TB medications by a trained individual. It is a case management strategy that helps ensure patients adhere to their prescribed therapy. For cases reported in 2017, the most recent year for which data are available, anti-TB therapy was administered using only DOT for 61.2% of patients, and 32.9% received anti-TB therapy with a combination of DOT and self-administered therapy (Table 10).

Completion of Treatment

The vast majority (95.8%) of 2017 patients who started treatment completed their treatment; 89.8% of those who were eligible to complete treatment within 1 year of diagnosis did so (Table 10).

Comorbid Conditions

Among all persons with TB, almost half (49.5%) reported none of the medical risk factors for TB that are collected in NTSS. Diabetes mellitus (20.7%) remains the most commonly reported medical risk factor for TB and is proportionately more common among non-U.S.–born persons (23.1%) than U.S.-born persons (14.4%) (Table 35 and Table 23).

Coinfection with human immunodeficiency virus (HIV) is a major risk factor for progression of latent TB infection to TB disease. Among persons with TB in 2019 who were alive at diagnosis, HIV status was known for 90.7%, and 4.7% of persons with known HIV status were coinfected with HIV (Table 11). Among TB cases diagnosed among persons aged 25–44 years, 95.2% had known HIV status, and 7.6% of these persons were HIV-positive (Table 11). New in 2019, we also report the number and percentage of persons aged 45–64 years who were coinfected with HIV; among those, 93.7% had known HIV status, and 6.0% were HIV-positive (Table 11).

Having an immunocompromising condition other than HIV (8.2%) and having been a close contact of a person with infectious TB (8.2%) were reported with equal frequency (Table 23). Having an immunocompromising condition other than HIV and having been a contact of a person with infectious TB were each more commonly reported among U.S.-born (8.7% and 17.5%, respectively) compared with non-U.S.–born persons (8.0% and 4.5%, respectively) (Table 23).

Congregate Settings

Living in congregate settings, including homeless shelters, correctional facilities, and long-term–care facilities, is a risk factor for TB. Having experienced homelessness within 12 months of TB diagnosis was reported for 383 (4.6%) of cases among persons aged ≥15 years nationally in 2019 (Table 38). This compares with 368 (4.3%) of TB cases among persons aged ≥15 years with reported homelessness in 2018. Reporting areas with the highest percentage of cases among persons aged ≥15 years reporting homelessness include Montana (50%, 1 of 2 cases), Maine (29.4%, 5 of 17 cases), Mississippi (23.1%, 12 of 52 cases), and South Dakota (18.8%, 3 of 16 cases) (Table 38).

Current residents of correctional facilities represented 3.1% of TB cases among persons aged ≥15 years. Correctional facilities include federal prisons (14.0% of TB cases diagnosed among residents of correctional facilities), state prisons (15.5%), local jails (27.9%), and other facilities (39.6%) (Table 37). Other correctional facilities include detention facilities operated by U.S. Immigration and Customs Enforcement (ICE), although persons can be in ICE custody without being in an ICE-operated facility. Of the TB cases diagnosed in all correctional facilities with information about ICE custody, 45.8% occurred among persons who were in ICE custody, either at an ICE-operated facility or another correctional facility (Table 37). Reporting areas with the highest percentage of cases among persons aged ≥15 years who were diagnosed while a resident of a correctional facility include Arizona (25.3%, 43 of 170 cases), Mississippi (15.4%, 8 of 52 cases), South Dakota (12.5%, 2 of 16 cases), West Virginia (10.0%, 1 of 10 cases), and Texas (9.7%, 99 of 1,016 cases) (Table 37).

During 2019, 1.8% of TB cases were diagnosed among current long-term–care facility residents aged ≥15 years; however, higher proportions were reported among certain reporting areas, including Rhode Island (7.1%, 1 of 14 cases), Kansas (5.9%, 2 of 34 cases), Mississippi (5.8%, 3 of 52 cases), and Nevada (5.8%, 3 of 52 cases) (Table 39).

Substance Misuse

Substance misuse is also a TB risk factor. The most commonly reported type of substance misuse during the year preceding diagnosis among persons with TB aged ≥15 years was excessive use of alcohol (8.1%), followed by non-injection drug use (7.5%), and injection drug use (1.2%) (Table 40, Table 41, and Table 42).

Successful therapy completion for TB patients is an important performance indicator for TB programs. Among persons diagnosed with TB during 2017 who were alive at diagnosis and eligible to complete TB treatment within one year, 89.8% completed treatment within one year and 95.8% ever completed TB treatment (Table 10). Consistent with 2016, 6.7% of patients in 2017 who started TB treatment died before they could complete treatment, and 0.3% had to stop TB treatment because of an adverse event (Table 12). Other reasons for not completing treatment include loss to follow-up before completing treatment (1.2%), refusal (0.7%), and other or unknown/unreported reasons (3.8%) (Table 12).

Among all TB cases diagnosed during 2017, a total of 768 (8.6%) patients died, with 256 (33.3%) of those deaths attributed to TB disease or TB treatment (Table 13). Of the 768 deaths, 165 (21.5%) were dead at the time of TB diagnosis; 29.7% of those deaths were attributed to TB (Table 13). The remaining 603 (78.5%) deaths occurred after diagnosis, of which 34.3% were attributed to TB (Table 13).

Time required for a patient’s positive sputum culture to convert to negative is a key indicator of treatment effectiveness. Among 5,115 cases during 2017 with positive sputum cultures, 4,422 (86.5%) had documented sputum culture conversion to negative (Table 14). Among the 632 (12.4%) cases for which sputum culture conversion was undocumented, the most common reason was that the patient had died (36.1%) before sputum culture conversion; however, a portion of these cases (19.0%) did not have a known reason reported for not having documented sputum culture conversion (Table 14).

Genotype Clusters

TB genotyping uses laboratory methods to characterize a small portion of the mycobacterial genome, detect strain variations, and designate isolates from culture positive cases as having particular genotypes. Clusters of TB cases with matching genotypes are an indication of possible recent TB transmission. In this report, clusters are defined based on further spatiotemporal criteria; a TB case is clustered if it had a matching genotype with one or more other cases in the same county or county-equivalent area during the 3-year period of 2017–2019. For this time period, 19.2% of TB cases were clustered. Clustering was more frequent for cases in U.S.-born persons (33.9%) compared to cases in non-U.S.–born persons (13.4%) (Table 24). However, the majority (66.6%) of clusters were composed of only two cases (Table 25). Molecular surveillance for TB clusters relies on a high genotyping surveillance coverage, and the percentage of all culture positive TB cases for which there was a genotyped isolate has been consistently ≥97% since 2015 (Table 16).

Estimates of Recent Transmission

CDC uses genotyping data to estimate the number of TB cases that are attributed to recent transmission. Estimates are based on whether a TB case has a plausible source case with a matching genotype in a TB patient who resides ≤10 miles and was diagnosed ≤2 years prior to the case.^8,9 Of 13,577 genotyped cases reported nationally during 2018–2019, 1,703 (12.5%) were attributed to recent transmission (Table 57). This compares with the previous 2-year period, 2016–2017, when 13.1% of genotyped cases were attributed to recent transmission. While estimates of recent transmission vary across reporting areas, 47 reporting areas had at least one case reported in 2018–2019 that was attributed to recent transmission (Table 57).

Cases that are attributed to recent transmission are further assessed for whether they belong to a plausible chain of transmission of ≥6 cases within a 3-year time period. If they meet these criteria, TB cases are additionally attributed to extensive recent transmission. Nationally, 557 (4.1%) genotyped cases reported in 2018–2019 were attributed to extensive recent transmission, compared with 625 (4.6%) genotyped cases for 2016–2017. Forty-six counties or county-equivalent areas had >5% of their genotyped cases attributed to extensive recent transmission in 2018–2019 (Table 58). Of these 46 counties or county-equivalent areas, 26 also had >5% of genotyped cases attributed to extensive recent transmission during 2016–2017.

Disparities in the estimated proportions of cases attributed to recent transmission and extensive recent transmission have persisted among certain racial/ethnic groups and persons with social and behavioral risk factors, although these estimates are declining in some groups (Table 59). Temporally, proportions for both estimates declined among non-Hispanic Black/African American persons and among persons reporting drug use, excess alcohol use, and homelessness within the past year, compared with the previous 2-year period. However, proportions for both estimates increased among Native Hawaiian/Other Pacific Islanders and the proportion of cases attributed to recent transmission increased among American Indians/Alaska Natives.

In 2019, TB cases and incidence rates in the United States continue to decline, but TB remains an important public health problem because the rate of annual decline is inadequate to achieve TB elimination this century. Also, of concern, TB continues to disproportionately affect some U.S. populations, particularly people from racial and ethnic minority groups. TB incidence rates remained steady or decreased from 2018 for all racial and ethnic groups, but incidence rates are 1.8–34.3 times higher among persons from racial and ethnic minority groups compared to non-Hispanic White persons. The majority of TB cases continued to occur among non-US–born persons, and 13.5% of cases among non-U.S.–born persons occurred within one year of arrival in the United States. The percentage of cases attributed to recent transmission continued to decrease in 2018–2019, but >90% of reporting areas reported at least one case attributed to recent transmission. To accelerate progress towards elimination, CDC supports a dual approach that includes diagnosing and treating every case of TB disease and preventing future cases by expanding testing and treatment for people with latent TB infection (LTBI).