TB in US at all-time low, but global decline small

The US Centers for Disease Control and Prevention (CDC) released new numbers today about tuberculosis (TB) in the United States in advance of World TB Day, which takes place on Mar 24, noting that cases have reached an all-time low. 

In 2018 the CDC noted a total of 9,029 new TB cases in the United States, representing a 0.7% decrease from 2017. The incidence in 2018 was 2.8 per 100,000 persons, which is the lowest number recorded since the CDC began tracking TB in 1953.

The findings were published today in Morbidity and Mortality Weekly Report (MMWR).

But the incidence of TB among foreign-born residents of the US is preventing total elimination of the disease. And without a big increased investment in detection and treatment of latent TB infection (LTBI), the US will not see the elimination of TB in the 21st century, the authors said.

TB is 14 times more likely to be diagnosed in foreign-born residents than those born in the United States, the CDC said. In 2018, approximately two-thirds of new TB cases (6,276 [69.5%]) occurred in non–US-born persons, whereas 2,662 (29.5%) occurred in US-born persons.

In 46.3% of new TB cases diagnosed among foreign-born residents, the disease was diagnosed 10 or more years after the patient first arrived in America. That finding is consistent with data which shows the reactivation of remotely acquired LTBI has been responsible for more 80% of domestic TB cases in the US.

Mexico, the Philippines, India, Vietnam, and China are the top five countries of birth of non–U.S.-born persons with TB.

Four states represent half of all TB cases

As has been the case for more than 20 years, California, Florida, New York, and Texas reported half of all TB cases in 2018.

Overall, TB incidence declined 1.3% from 2017 to 2018, and at an average of 1.6% per year during the last 4 years. Alaska has the highest TB incidence rate, at 8.5 cases per 100,000 persons.

The CDC said that testing at-risk populations for LTBI is necessary to eliminate TB.

"Given that the estimated prevalence of LTBI is higher among non–U.S.-born persons and that rates of TB disease are much higher in this group, the detection and treatment of LTBI among non–U.S.-born persons should be prioritized. CDC is working with its state and local partners to develop an LTBI surveillance system to track effectiveness of public health measures to address LTBI," the authors concluded.

Global decline not on track to meet 2030, 2035 goals

In a separate study on the global scope of TB, CDC authors said 2017 brought a slight decline to TB incidence and deaths worldwide, but the declines are not significant enough to meet U.N. Sustainable Development Goals and the World Health Organization (WHO) End TB Strategy targets for 2030 and 2035.

"In 2017, an estimated 10 million incident cases of TB and 1.57 million TB deaths occurred, representing 1.8% and 3.9% declines, respectively, from 2016. Numbers of TB cases and disease incidence were highest in the WHO South-East Asia and Africa regions, and 9% of cases occurred among persons with HIV infections," the CDC said.

TB is the leading cause of death among persons living with human immunodeficiency virus (HIV) infection, accounting for approximately 40% of deaths in this population, the CDC said. Moreover, as much as 25% of the world’s population has LTBI. Those infections could be averted with TB preventive treatment (TPT).

"Available data indicate relatively slow uptake of TPT and a stagnation in TPT administration among persons with HIV infection in recent years; current TPT coverage falls well below the End TB Strategy target level of ≥90% coverage by 2025," the CDC said.

Slow decline also noted in EU

A new study from the European Centre for Disease Prevention and Control (ECDC) published in Eurosurveillance corroborates the CDC’s findings. In the ECDC study, researchers measured incidence reductions in the European Union (EU) against the UN’s Sustainable Development Goals target reductions. 

In order to end TB by 2030,  TB incidence should be 80% lower in 2030 compared with 2015; the number of TB deaths should be 90% lower. But in 2017, the TB rate was 10.7 per 100,000 population in the EU, representing an overall decline of 10% since 2015, and an average annual decline of 4.8% from 2008 through 2017.

"If the 4.8% average annual decline continued unchanged, the EU/EEA would reach a TB notification rate of 5.7 per 100,000 population in 2030. The annual average decline required to reach the target is 10.9%," the authors said.

See also:

Mar 22 MMWR US TB study

Mar 22 MMWR global TB study

Mar 21 Eurosurveillance study

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