Tuberculosis in the United States: The Good, the Bad and the Ugly

Number and rate of newly diagnosed tuberculosis (TB) cases among U.S.-born and foreign-born persons.  From: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6410a2.htm  

In time for World Tuberculosis (TB) Day, the US Centers for Disease Control and Prevention released a summary of the TB cases that were reported to the National Tuberculosis Surveillance System in 2014.

The data paint a mixed picture.  The good news for the US is that for the 22nd consecutive year, the total number of TB cases reported in the United States has fallen.  In 2014, 9,412 new TB cases were reported in the United States, corresponding to an incidence of 3 cases per 100,000 people.  This incidence represents a 2.2% decrease from the number of TB cases reported in the US in 2013.

But there’s bad news hidden in these statistics.  First, the 2.2% decrease in TB incidence last year in the US represents the smallest decline seen in over a decade. In the last few years, annual decreases in TB incidence have been persistently slow, and sluggish declines raise serious raises concerns about US ability to meet the TB elimination goal CDC set in 1989. The current incidence of TB cases in the U.S. still far exceeds the CDC’s TB elimination goal of <1 case per 1 million population?  And at the rate TB incidence has been declining in recent years, it may take well a hundred or more years for US to achieve TB elimination.

A second cause for concern is the continued disparity in incidence between US and foreign-born individuals.  Last year, the incidence of TB in the foreign born was 13.4 times that of those born in the US.  Efforts to slow TB incidence among the foreign-born also lag.  While last year’s incidence in TB among those born in the US decreased by 6.8%, there was only a 1.5% decrease among the foreign-born.  This is bad news because foreign-born individuals account for the majority of TB cases reported in the US. 

But why should the US care about TB?  First, TB is a leading cause of sickness and death worldwide.  In 2013, 9.0 million people developed TB and 1.5 million died.  Despite the availability of effective treatment, the daily death rate of TB (>4,000 people/day) dwarfs that of many other lethal diseases, including Ebola.

Compared to these global statistics, 9,000 or so cases of TB in the US hardly seem worth mentioning.  But global statistics have a direct connection to what we are likely to see in the US, as studies have found that ~80% of active TB cases in the US are likely caused by reactivation of prior infection--likely acquired abroad--rather than newly transmitted infections. Therefore, an inability to drive down TB incidence globally will surely slow progress towards TB elimination in the US.

As recent news reports show us, even one case of TB in the United States can have considerable impact on a community. Following the discovery of an active TB case at a Kansas high school, a public health investigation identified 27 students who also tested positive for TB.  Though the students do not have symptoms of active TB, their positive blood test indicates they are likely latently infected with TB and will have to undergo up to 9 months of treatment to ensure that their infection does not develop into active disease.

Another reason why the US should be concerned about TB here and abroad is the emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) TB. The WHO estimates that in 2013, close to a half of a million new cases of MDR and XDR TB occurred across the globe. In some countries, as many as 35% of first time cases and 75% of previously treated cases were caused by XDR and MDR. The continued occurrence of these cases is worrisome. Compared to drug-susceptible TB, MDR and XDR are far more difficult and require much more time to treat. 

Though the percentage of US drug resistant TB cases have so far remained relatively stable in recent years, last year the US did see a small increase in the number of resistant cases.  While a few extra cases may not seem like much, at an estimated cost of $130,000-$430,000 to treat a single patient, small increases in the number of MDR and XDR TB patients can be crippling for health departments that often shoulder the bill for treating these patients.

The third reason why TB is an important issue for the US is because the ability to control TB should be a good indicator of our readiness to respond to other communicable diseases. The core of skills required for TB control—case detection, laboratory analysis, contact tracing, infection control—are foundational capabilities for communicable disease control.  Therefore, commitment to reduce TB incidence provides regular opportunities to exercise for responding to measles, Ebola and other rarer occurrences.

Despite the importance of TB to US public health, US commitment towards TB elimination is lagging. While the number of cases of TB in the US may have decreased in the last 20 years, the costs of TB control certainly have not.  Many factors—from the availability of more powerful, but more costly, laboratory tests, the continued occurrence of drug resistant TB and other more complicated forms of TB, and the high costs of treatment infections—have all placed additional strains on public health agencies in charge TB control programs.

The ugly news is that despite these persistent—and arguably growing challenges—US  funding for TB control has declined.  The President’s Fiscal Year 2016 budget would cut USAID’s international TB control efforts by 19%. Domestically, federal funding for state/local TB control activities has remained flat for the last 10 years, which, factoring in inflation, has meant that that the amount of resources available for TB control have declined substantially.  Combined with state budget cuts following the recent recession, declining federal support for TB control has forced health departments to make tough choices.  A survey conducted by the National Tuberculosis Controllers Association found that sixty percent of TB control programs have had to eliminate staff as a result of shrinking budgets.  Twenty-five percent of programs reported having to restrict some essential TB activities, such as provision of directly observed therapy, contact and outbreak investigations.

Taken together, the news of disappointing declines in TB incidence and evidence that TB control programs are scaling back activities in light of declining budgets, raise important doubts about the prospects of eliminating TB from the United States and about our readiness for other infectious disease emergencies. In support of World TB Day, we should re-think this penny wise, pound foolish approach.