Featured Research

from universities, journals, and other organizations

US Soldiers In High-tuberculosis Areas Face New Epidemic: False Positives

Date:
June 2, 2008
Source:
American Thoracic Society
Summary:
US Army service members are increasingly deployed in regions of the world where tuberculosis is rampant, such as Iraq and Afghanistan, and the military now faces a growing medical problem. But it is not TB itself that is on the rise -- instead, the problem lies with the growing number of "pseudoepidemics," or clusters of false-positives.

U.S. Army service members are increasingly deployed in regions of the world where tuberculosis (TB) is rampant, such as Iraq and Afghanistan, and the military now faces a growing medical problem. But it is not TB itself that is on the rise--instead, the problem lies with the growing number of "pseudoepidemics," or clusters of false-positives for TB that are the result of universal testing with a notoriously inaccurate tuberculin skin test (TST) and inconsistent procedures for interpreting those tests in low-risk populations.

These false positives tests have become more than a mere institutional inconvenience or a momentary medical scare for Soldiers being tested. They are a real financial and medical burden because they inappropriately diverting limited funds and resources.

A recent study, published in American Thoracic Society's first issue for June of the American Journal of Respiratory and Critical Care Medicine, describes eight outbreaks of false-positive TB tests between 1983 and 2005. The study was led by U.S. Army Major James Mancuso, M.D., of the Uniformed Services University of the Health Sciences.

Recent deployments to Iraq and Afghanistan, which are reported to have among the highest rates of active TB in the world, have raised concerns about TB exposure. However, many service members do not have sufficient contact with locals to raise their risk of contracting TB. As a consequence, "testing after recent deployments to the endemic and hyperendemic areas has occasionally resulted in large numbers of U.S. Army service members with [positive tests] and massive efforts aimed at preventing active TB," wrote Dr. Mancuso.

Because the positive-predictive value of a test--that is, the likelihood of a positive result indicating an actual case--is dependent on the prevalence of disease in a population. The lower the prevalence of a disease, and the higher the variability in the test and testing procedures, the less the positive-predictive value of a test will be. "This may dramatically reduce the positive-predictive value of the test to below 50 percent," said Dr. Mancuso.

Dr. Mancuso and his colleagues conducted outbreak investigations in deployed locations such as the Balkans and Afghanistan, where they collected and reviewed medical records of reported active and latent TB cases in deployed U.S. Army service members. They then obtained the medical histories of these soldiers, including prior diagnoses and treatments, determined current symptoms and interviewed the subjects to identify other possible risk factors. Finally, they retested all available skin test converters.

"Repeat testing of converters (positives) found that 30 to 100 percent were negative on retesting," wrote Dr. Mancuso. In one case, 95 percent of positive TB tests (38 of 40 tests) from Army National Guard servicemen in Kosovo were subsequently found to be negative, and the pseudoepidemic was primarily attributed to variability with the test administration and reading, as well as to the specific type of test used.

"The testing of [a] predominantly low-risk population leads to false-positive results in individuals and pseudoepidemics of false-positive TST conversions in U.S. Army populations," Dr. Mancuso concluded, recommending three actions to reduce the occurrence of false positive skin tests and these apparent outbreaks: test only truly high-risk personnel; standardize testing procedures; and use the more reliable of the TST tests, Tubersol, in lower-risk populations such as the U.S. Army.

"As always, an individualized assessment of each patient's risk of tuberculosis should be used to target testing and treatment of latent tuberculosis infection. In the absence of other risk factors, clinicians and public health officials should interpret reported skin test conversions after deployment with caution," he added.


Story Source:

The above story is based on materials provided by American Thoracic Society. Note: Materials may be edited for content and length.


Cite This Page:

American Thoracic Society. "US Soldiers In High-tuberculosis Areas Face New Epidemic: False Positives." ScienceDaily. ScienceDaily, 2 June 2008. <www.sciencedaily.com/releases/2008/05/080530074251.htm>.
American Thoracic Society. (2008, June 2). US Soldiers In High-tuberculosis Areas Face New Epidemic: False Positives. ScienceDaily. Retrieved July 28, 2014 from www.sciencedaily.com/releases/2008/05/080530074251.htm
American Thoracic Society. "US Soldiers In High-tuberculosis Areas Face New Epidemic: False Positives." ScienceDaily. www.sciencedaily.com/releases/2008/05/080530074251.htm (accessed July 28, 2014).

Share This




More Health & Medicine News

Monday, July 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Trees Could Save More Than 850 Lives Each Year

Trees Could Save More Than 850 Lives Each Year

Newsy (July 27, 2014) A national study conducted by the USDA Forest Service found that trees collectively save more than 850 lives on an annual basis. Video provided by Newsy
Powered by NewsLook.com
Google's Next Frontier: The Human Body

Google's Next Frontier: The Human Body

Newsy (July 27, 2014) Google is collecting genetic and molecular information to paint a picture of the perfectly healthy human. Video provided by Newsy
Powered by NewsLook.com
What's To Blame For Worst Ebola Outbreak In History?

What's To Blame For Worst Ebola Outbreak In History?

Newsy (July 27, 2014) A U.S. doctor has tested positive for the deadly Ebola virus, as the worst-ever outbreak continues to grow. Video provided by Newsy
Powered by NewsLook.com
Losing Sleep Leaves You Vulnerable To 'False Memories'

Losing Sleep Leaves You Vulnerable To 'False Memories'

Newsy (July 27, 2014) A new study shows sleep deprivation can make it harder for people to remember specific details of an event. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins