Army studying 1st Infantry Division’s unusually high rates of TB exposure
July 12, 2005
WüRZBURG, Germany — Army medical officials are investigating why an unusually high percentage of 1st Infantry Division troops have tested positive for exposure to the lung disease tuberculosis after returning this spring from Iraq.
Dr. (Maj.) James Mancuso, chief of epidemiology for the Center for Health Promotion and Preventative Medicine-Europe, said 4 percent to 5 percent of deployed 1st ID troops reacted positively in the tuberculin skin test all of them received when they came home. During previous deployments to Bosnia-Herzegovina and Kosovo, he said, about 1 percent or 2 percent typically have been exposed.
Mancuso said a positive skin test is no cause for alarm.
“They are not infectious. They can’t transmit it to anyone else,” Mancuso said. “The bacteria is just lying there in [their] lungs.”
Even without treatment, only 10 percent of those exposed worldwide to TB ever develop the full-blown disease. With the Army’s mandatory nine-month treatment regimen using the drug isoniazid, he said, the rate drops to 1 percent. Soldiers must take one pill each day and can’t use any alcohol during the treatment.
The disease progresses slowly. Untreated active tuberculosis can cause the deterioration of the lungs and, eventually, death. Mancuso said it is common in underdeveloped countries.
“TB is endemic in Iraq,” he said. “Any time you have a war, TB gets worse. And Iraq already had a problem.”
Mancuso said the Army has long tested soldiers for TB exposure after deployments. In recent years, though, it has made its program uniform and added a second test between three and six months after the first one. That allows doctors to catch any cases missed in the first screening.
Mancuso said units returning from Iraq have shown markedly different rates of TB exposure. The 3rd Infantry Division, he said, which fought for Baghdad and went home six months later, showed an exposure rate near zero. The 101st Airborne Division, which joined in the invasion and stayed for a full year, showed a high exposure of 4 percent to 5 percent. The 1st Armored Division, which ended a 16-month deployment in late summer 2004, showed a 1 percent to 2 percent rate of infection.
But because of questions about the reading of test results, Mancuso said, the Army couldn’t be sure earlier data were accurate. With the 1st ID, the nurses were uniformly trained in how to give and read the results.
“I consider their data to be of good quality, and reliable,” he said.
However, the data is not being made public, at least not yet. The European Regional Medical Command referred requests for the 1st ID data to the Army Medical Command of the Surgeon General’s office.
Cynthia Vaughan, a medical command spokeswoman, said the data belonged to the units and wouldn’t be released without their consent. Maj. William Coppernoll, a 1st ID spokesman, said the division wouldn’t release its skin-test data, at least not until the second set of tests is completed.
It is known, though, that 1st ID deployed about 12,000 troops to Iraq. Based on Mancuso’s statistics, between 450 and 600 of those must have tested positive.
According to probabilities, four to six of them might eventually develop tuberculosis. Until now, he said, only one soldier who served in Iraq, a 101st Airborne veteran, has later developed TB. But he had tested positive for exposure before he deployed.
Maj. Heidi Whitescarver, chief of preventative medicine at the Würzburg Army Hospital, said for the study every 1st ID soldier who tests positive is being given a voluntary one-page questionnaire as part of the 2-month-old study.
Besides demographic data, it asks about exposure in Iraq to people at high-risk for TB infection, amount of time spent off base, length of deployment and location. A control group of unexposed troops also is being questioned.
Whitescarver said epidemiologists hope the survey will reveal what factors lead to TB exposure so the risk to troops can be cut on future deployments.
“We would make recommendations to commanders based on this,” she said.
“There’s power in the data, especially if it is statistically significant.”
Q & A: The facts about TB
Q: What is tuberculosis?
A: Tuberculosis is a chronic bacterial infection that is spread through the air and usually infects the lungs. About 2 billion people worldwide are infected with the TB bacterium, a condition called latent tuberculosis infection, but have no symptoms and cannot spread the disease to others. But each year, about 8 million people develop active TB, and 3 million die.
Q: How do people get TB?
A: TB is spread from person to person in tiny microscopic droplets when a TB sufferer coughs, sneezes, speaks, sings or laughs. Only people with active disease are contagious. Adequate ventilation can prevent the transmission of TB.
It usually takes lengthy contact with someone with active TB before a person can become infected. On average, people have a 50 percent chance of becoming infected if they spend eight hours a day for six months, or 24 hours a day for two months, alongside someone with active TB. After drug treatment for at least two weeks, people with TB are no longer contagious and do not spread the germ to others.
Q: What is “active” disease?
A: One in 10 infected people may develop active TB. The risk of developing the active disease is greatest in the first year after infection, but active disease may not occur for many years.
One in three patients with TB will die within weeks to months if the disease is not treated. For the rest, their disease either goes into remission (halts) or becomes chronic and more debilitating with cough, chest pain, and bloody sputum. Symptoms of TB involving areas other than the lungs vary, depending upon the organ affected.
Q: Can TB be cured?
A: With appropriate antibiotic treatment, TB can be cured in more than nine out of 10 patients. Doctors can identify most infected people through a skin test. They will inject a substance under the skin of the forearm. If a red welt forms around the injection site within 72 hours, the person may have been infected. This doesn’t necessarily mean he or she has the active disease.
Treatment usually combines several antibiotic drugs, which are given for six to 12 months.
Source: National Institute of Allergy and Infectious Diseases, National Institutes of Health