- Category: Tuberculosis (TB)
- Published on Friday, 23 March 2012 00:00
- Written by Liz Highleyman
Tuberculosis (TB) is the leading cause of death for people with HIV worldwide -- killing approximately 350,000 people in 2010 -- and the second leading cause for the population as a whole. Globally, an estimated 12 million people are living with latent TB. In the U.S., more than 10,500 new TB cases were reported in 2011, mostly in HIV negative people. Multidrug-resistant (MDR), extensively drug-resistant (XDR), and totally drug-resistant (TDR) TB are a growing concern.
World TB Day -- which takes place annually on March 24, the date Robert Koch announced his discovery of Mycobacterium tuberculosis in 1882 -- is an occasion to raise awareness about TB and encourage screening and care. Researchers are working on better, more rapid treatments for TB as well more effective vaccines.
On March 2 the World Health Organization (WHO) released updated guidelines for managing TB in people with HIV. WHO estimates that more than 900,000 lives were saved over the past 6 years by increased screening and treatment of both HIV and TB around the world.
Medecins sans Frontieres/Doctors without Borders recently warned that multidrug-resistant TB is more widespread than previously believed. MDR-TB, which does not respond to standard treatment, has been reported in most regions of the world. "Wherever we're looking for drug-resistant TB we're finding it in very alarming numbers" said MSF medical director Leslie Shanks. "And that suggests to us that the current statistics that are being published about the prevalence of MDR-TB are really just scratching the surface of the problem."
TB is highly prevalent in South Africa, in conjunction with a widespread HIV epidemic. A study presented at the recent Conference on Retroviruses and Opportunistic Infections (CROI 2012) found that giving preventive isoniazid therapy to all people working in certain gold mines did not reduce TB incidence or death at the community level, though it did benefit treated individuals.
TB in the U.S.
In advance of World TB Day the Centers for Disease Control and Prevention (CDC) published preliminary 2011 tuberculosis surveillance data for the U.S. in the March 23, 2012, issue of Morbidity and Mortality Weekly Report.
A total of 10,521 cases of TB were reported in 2011, for a rate of 3.4 cases per 100,000 people. As with many diseases, the TB burden disproportionately affects marginalized population groups including racial/ethnic minorities, foreign-born people, and people living with HIV.
In 2011 TB rates were 7 times higher for Hispanics/Latinos, 8 times higher for blacks, and 25 times higher for Asians compared with whites (5.9, 6.3, and 21.4 cases per 100,000 people, respectively). Foreign-born individuals were 12 times more likely to have TB than people born in the U.S., comprising nearly two-thirds of all cases. Numbers also varied regionally, ranging from 0.7 cases per 100,000 people in Maine to 9.3 in Alaska. The 4 states that reported more than 500 cases -- California, Florida, New York, and Texas -- together accounted for about half of all reported cases.
Only 8% of people with TB were HIV positive, but this far exceeds the proportion with HIV in the population. Drug-resistant TB is less of a problem in the U.S. compared with some other countries, standing at 1.3% of cases.
Despite these sobering numbers, TB has continued to decline in the U.S., and in 2011 reached an all-time low since national reporting began in 1953. The percentage decline for 2011 was larger than the average decline of 3.8% per year from 2000 to 2008, but did not match the record 11.4% decline seen from 2008 to 2009.
This year's Retrovirus Conference, held this month in Seattle, devoted an unusual number of presentations to TB, especially among people with HIV. Eric Nuermberger from Johns Hopkins gave a plenary talk, "From the Cage to the Clinic," looking at development of better TB regimens for the next 40 years. An oral abstract session featured the latest studies of TB and vaccine-preventable diseases, and a symposium covered "Scientific Advances in TB Pathogenesis and Treatment." All these sessions can be viewed on the CROI website, in the listing for Thursday.
"To transform the field, we must address long-standing challenges in TB research, such as identifying the factors involved in the immune control of latent TB infection that allow 90 percent of otherwise healthy TB-infected individuals to never develop active disease," said Christine Sizemore, Richard Hafner, and Anthony Fauci in a World TB Day statement from the National Institute of Allergy and Infectious Diseases. "We need to use novel scientific tools and apply modern approaches to answer this and other fundamental questions. In this regard, a renewed focus on fundamental TB research will enable us to refine our strategies for developing and applying innovative interventions against TB."
"Eliminating TB in a generation, while an ambitious goal, can become a reality through the continued commitment and collaboration of the key stakeholders in biomedical research and global health," they continued. "Fostering even closer integration of biomedical research with the TB control community will help assure that new medical tools are applied in the most effective manner to make TB a disease of the past."
More information and resources are available from the following sources:
Stop TB Partnership: World TB Day: http://www.stoptb.org/events/world_tb_day/2012.
CDC: World TB Day 2012: http://www.cdc.gov/tb/events/WorldTBDay.
CDC: Fact sheet -- TB in the U.S.: A Snapshot, 2011: http://www.cdc.gov/nchhstp/newsroom/docs/TB-Trends-Fact-Sheet.pdf.
WHO: Global Tuberculosis Control 2011: http://www.who.int/tb/publications/global_report/en.
WHO: FAQ on Totally Drug-Resistant TB: http://www.who.int/tb/challenges/mdr/tdrfaqs/en/index.html.
An International Roadmap for Tuberculosis Research: http://www.stoptb.org/assets/documents/resources/publications/technical/tbresearchroadmap.pdf.
Medecins sans Frontieres. Alarming Scale of Multidrug-Resistant TB Requires Rapid Response. Press release. March 20, 2012.
CDC. Fact sheet -- TB in the U.S.: A Snapshot, 2011. March 23, 2012. http://www.cdc.gov/nchhstp/newsroom/docs/TB-Trends-Fact-Sheet.pdf.
R Miramontes,R Pratt, S Price, et al. Thomas. Trends in Tuberculosis -- United States, 2011. Morbidity and Mortality Weekly Report 61(11):181-185. March 23, 2012.
National Institute of Allergy and Infectious Diseases. World TB Day Statement from Christine F. Sizemore, Richard E. Hafner, and Anthony S. Fauci. March 24, 2012.