Transmission of tuberculosis within healthcare settings is rarely reported. However, the disease endures, and the potential for disruptive unsuspected cases or healthcare workers developing active disease requires continued vigilance.
For example, in separate incidents in the last two years, hospitals in the Seattle area have had to alert patients that they may have been exposed to a patient and a healthcare worker with active TB. No transmission occurred in either case, King County health officials reported.
The problem—even as TB dips to record lows in the United States—is that there is a vast reservoir of Mycobacterium tuberculosis dormant in its latent state in this country and worldwide. That means some 13 million people in the United States—and one-third of the human population beyond U.S. boundaries—has a 5% to 10% chance of developing active TB at some point in life and becoming infectious.
Although the CDC recently reported that TB continues to decline in the United States, the rate of reduction is not on a pace to reach the goal of tuberculosis eradication.
CDC data show that 9,287 new tuberculosis cases were reported in the United States in 2016.1 “This provisional count represents the lowest number of U.S. TB cases on record and a 2.7% decrease from 2015. The 2016 TB incidence of 2.9 cases per 100,000 persons represents a slight decrease compared with 2015 (-3.4%). However, epidemiologic modeling demonstrates that if similar slow rates of decline continue, the goal of U.S. TB elimination will not be reached during this century. Although current programs to identify and treat active TB disease must be maintained and strengthened, increased measures to identify and treat latent TB infection (LTBI) among populations at high risk are also needed to accelerate progress toward TB elimination.”
Treatable but Deadly
TB is a largely treatable disease that still manages to kill millions worldwide and has developed strains highly resistant to drug therapy. Impoverished crowded communities in Asia and Africa still suffer the major toll of TB, but of course any disease in the world is but a plane ride away.
“TB cases continue to occur in every state and region in the United States,” the CDC reports. “Analysis suggests that eliminating TB will require a dual approach: strengthening existing TB programs/systems to diagnose and treat active TB disease, and intensifying efforts to identify and treat latent TB infection among those who are infected with TB bacteria but are not yet sick.”
The CDC estimates that over the last two decades, control efforts have prevented as many as 300,000 people from developing TB, which has potentially saved more than $6 billion in costs.
“Unfortunately, these efforts alone will not be sufficient,” the CDC notes. “More than 85% of U.S. TB cases are associated with reactivation of latent TB infection, often acquired years earlier.”
TB can reach high levels of resistance if treatment is not administered properly and drugs are not taken with complete compliance.
“Treating a single person for drug-susceptible TB disease costs about $18,000—some 36 times more than the $500 it costs to proactively treat a person for latent TB infection,” the CDC reports. “The cost for treating drug-resistant TB disease is even higher, ranging from $154,000 to $494,000, up to nearly 1,000 times treatment costs for a latent TB infection.”
In 2015 data—the most recent available—88 cases of multidrug-resistant TB occurred in the United States, comprising 0.4% of U.S.-born and 1.2% of foreign-born people with culture-confirmed TB cases, the CDC notes. Among those 88 multidrug-resistant TB cases, 72 of them, or 81.8%, occurred in people with no reported prior history of TB disease. Only one case of extensively drug-resistant TB—which can be virtually untreatable—occurred in the United States.
State-specific TB incidence for 2016 ranged from 0.2 cases per 100,000 persons in Wyoming to 8.3 in Hawaii, with a median state incidence of 1.9. California, Florida, New York, and Texas reported more than 500 cases each in 2016, accounting for 51% of reported cases nationwide. Seven other states and Washington, DC exceeded the national TB incidence rate: Alaska, Arkansas, Georgia, Maryland, Minnesota, New Jersey, and North Dakota.
“Among 9,287 TB cases reported in 2016, U.S.-born persons accounted for 2,935 (31.6%) cases, and 6,307 (67.9%) cases occurred among foreign-born persons,” the CDC reports. “TB incidence among U.S.-born persons (1.1 cases per 100,000) decreased 8.4% from 2015. Incidence among foreign-born persons (14.6 cases per 100,000) decreased 3.2% from 2015, but was approximately 14 times the incidence among U.S.-born persons.”
REFERENCE
- CDC. Tuberculosis —United States, 2016. MMWR 2017;66(11):289–294
