Although preliminary tuberculosis (TB) surveillance data for 2016 demonstrate slight declines in the number and incidence of U.S. TB cases since 2015 (a drop of 2.7 percent in the number of reported cases and a 3.4 percent drop in incidence, or number of cases per 100,000 people), the goal of eliminating the disease will not be reached by the end of this century if these slow rates of decline continue.
That's according to a Morbidity and Mortality Weekly Report (MMWR)(www.cdc.gov) the CDC published on March 24.
"The findings suggest that unless progress against TB is accelerated in the United States, we will not be able to eliminate TB in the near future, or even this century," said Philip LoBue, M.D., director of the CDC's Division of Tuberculosis Elimination at the National Center for HIV/AIDS, Viral Hepatitis, STD and TB Prevention, in a March 23 statement(www.cdc.gov) marking World TB Day.
Findings From the MMWR
In 2016, a total of 9,287 new TB cases were reported in the United States. Health departments in all 50 states and the District of Columbia electronically report verified cases of TB to the CDC that meet its case definition for the disease.
- Preliminary tuberculosis (TB) surveillance data for 2016 indicate that despite slight declines in TB case numbers and rates in the United States since 2015, more can be done to eliminate the disease.
- In 2016, a total of 9,287 new TB cases were reported in the United States, most of which were among foreign-born individuals.
- Because about 90 percent of TB cases in foreign-born patients are attributable to reactivation of latent tuberculosis infection (LTBI), targeted testing for and treatment of LTBI among foreign-born patients from countries with high TB prevalence is recommended.
These reports include demographic and clinical information, as well as medical and social risk factors for TB. Patients with reported TB are classified as U.S.- or foreign-born according to established criteria; race/ethnicity is self-reported. U.S. Census Bureau midyear population estimates provide the denominators used to calculate overall TB incidence. Current Population Survey(www.census.gov) data provide the population denominators used to calculate TB incidence according to national origin and racial/ethnic group.
The MMWR article broke down TB incidence by state, showing a range from 0.2 cases per 100,000 people in Wyoming to 8.3 cases per 100,000 in Hawaii, with an overall median state incidence of 1.9 cases.
Twelve states (Alaska, Arkansas, California, Florida, Georgia, Hawaii, Maryland, Minnesota, New Jersey, New York, North Dakota and Texas) and the District of Columbia reported incidences higher than the national incidence. Also, consistent with previous years, four states (California, Florida, New York and Texas) reported more than 500 cases each in 2016, accounting for nearly 51 percent of cases reported nationally.
Of the total number of TB cases reported in 2016, U.S.-born residents accounted for about 32 percent of cases, foreign-born individuals accounted for about 68 percent, and 0.5 percent of cases occurred in patients whose nationality was unknown.
Among foreign-born patients with TB, the highest incidence was among Asians (26.9 cases per 100,000), followed by non-Hispanic blacks (22.3) and Hispanics (10.0). Most foreign-born racial/ethnic groups experienced gradual decreases in incidence between 2013 and 2016.
Because about 90 percent of TB cases in foreign-born patients are attributable to reactivation of latent tuberculosis infection (LTBI), the MMWR recommended targeted testing for and treatment of LTBI among foreign-born patients from countries with high TB prevalence. Workers in high-risk congregate settings are also at increased risk for TB and should be included as part of a targeted testing and treatment approach.
Others at particular risk for TB infection or progression from LTBI to active disease who also may be considered for such an approach include
- close contacts of patients with infectious TB;
- patients with immunosuppression;
- individuals with other medical conditions associated with progression from LTBI to active disease, such as diabetes, chronic renal failure or silicosis; and
- people with fibrotic changes on chest radiograph that suggest inactive TB disease.
Last year, the U.S. Preventive Services Task Force (USPSTF) recommended(www.uspreventiveservicestaskforce.org) screening for LTBI in asymptomatic adults at increased risk for TB, a recommendation with which the AAFP agreed in its own recommendation statement. According to the USPSTF, among those considered to be at increased risk are patients who have lived in countries with a high prevalence of TB and people who have lived in group settings where exposure to TB is more likely, such as homeless shelters or correctional facilities.
Better Plan to Combat TB
LoBue said in his statement that analyses suggest eliminating TB will require a dual approach that consists of
- strengthening existing TB programs/systems to diagnose and treat active disease and
- intensifying efforts to identify and treat LTBI among those who are infected with the bacteria but who are not yet sick.
Currently, U.S. efforts to control TB focus on quickly identifying and treating those with active disease to prevent ongoing transmission. During the past 20 years, the CDC and health departments across the country have prevented as many as 300,000 patients from developing TB, saving more than $6 billion, LoBue said.
Still, it's estimated there are as many as 13 million people in the United States living with LTBI and, if left untreated, 5 percent to 10 percent of them will develop active disease.
"The good news is that we have more tools than ever to rapidly diagnose and treat latent TB infection and prevent the development of TB disease," LoBue said. "With better diagnostic tests, shorter treatments and new guidelines to assist physicians in testing, the United States has a greater opportunity than ever before to eliminate TB in this country."
LoBue said the dual approach to combating LTBI and TB disease would not only reduce suffering but also would substantially lower costs.
For example, he said treating a single person for drug-susceptible TB disease costs about $18,000 -- or about 36 times more than the $500 it costs to proactively treat a patient for LTBI. The cost to treat drug-resistant TB is even higher, ranging from $154,000 to $494,000 -- or 300 to nearly 1,000 times the cost to treat LTBI.
Furthermore, to eliminate TB in the United States, LoBue said public health systems and private practices must work together.
"Because current health department staffing is not sufficient to address the large number of people at risk for latent TB infection, we must broaden the responsibility and engage health care providers serving populations most likely to be susceptible to move from latent TB infection to active TB disease," he said.
This includes not only people who travel to countries with high TB prevalence or who live in group settings, LoBue reiterated, but also patients with weakened immune systems and those who smoke or are exposed to second-hand smoke.
"TB is a preventable and curable disease," he said. "We've come a long way in fighting the disease in the past century. But in order to reach TB elimination, we must intensify our efforts and implement a dual approach to put an end to a disease that has plagued mankind for thousands of years."
Related AAFP News Coverage
USPSTF, AAFP: Screen Adults at Increased Risk for Latent TB Infection
Evidence Supports Effective Screening Tests, Treatments